Neuro Flashcards
most common cause of ventral cord syndrome?
Symptoms?
How much of the cord?
Ventral cord syndrome
Assoc Prof Frank Gaillard◉◈ and Dr Prashant Mudgal et al.
Ventral cord syndrome (also known as anterior cord syndrome) is one of the incomplete cord syndromes and affects the anterior parts of the cord resulting in a pattern of neurological dysfunction dominated by:
- motor paralysis and
- loss of pain, temperature and autonomic function.
Anterior spinal artery ischaemia is the most common cause.
Terminology
Ventral cord syndrome encompasses all causes of damage to the anterior spinal cord regardless of aetiology (see below).
In contrast, anterior spinal artery syndrome, also known as Beck’s syndrome, denotes a ventral cord syndrome specifically due to ischaemia/infarction of the anterior two-thirds of the spinal cord due to involvement of the anterior spinal artery.
Clinical presentation
Involvement of the anterior half to two-thirds of the spinal cord results in a predictable pattern of neurological impairment consisting of:
- complete motor paralysis below the level of the lesion due to involvement of the anterior horn cells and corticospinal tracts
- loss of pain and temperature at and below the level of injury due to involvement of spinothalamic tracts
- autonomic dysfunction: orthostatic hypotension due to involvement of lateral horn cells 6
- bladder and bowel dysfunction and sexual dysfunction may arise depending on the level of the lesion
Importantly 2-point discrimination, proprioception and vibratory senses are normal due to intact posterior columns and posterior grey matter.
Pathology
Ventral cord syndrome is caused by a variety of processes, the most common one being ischaemia due to occlusion of anterior spinal artery, which in turn is the result of a number of underlying processes. As such, the list of causative pathologies is very similar to that of acute spinal cord ischaemia syndrome.
Causes of ventral cord syndrome include 1-5:
ischaemia/infarction (anterior spinal artery syndrome)
atherosclerotic thromboembolism
aortic pathology
aortic aneurysm
aortic thrombosis
aortic dissection
aortic surgery/intervention
anterior spinal artery pathology
penetrating trauma (e.g. stabbing)
arterial dissection (e.g. catheter angiography)
fibrocartilaginous embolism
external compression/damage of the anterior spinal cord
herniated disc
spinal tumour (e.g. intrathecal extramedullary)
epidural collections (e.g. epidural haematoma and epidural abscess)
kyphoscoliosis
trauma
vertebral body fractures
direct stab injuries
Radiographic features
For a description of the imaging features please refer to acute spinal cord ischaemia syndrome.
Treatment and prognosis
Prognosis of anterior cord syndrome is worst among all other spinal cord injury syndromes 5. It is associated with high mortality and poor functional outcome in terms of poor recovery of motor power and coordination.
Treatment is focussed on treating the primary cause of anterior spinal artery insufficiency and general supportive treatment and care.
History and etymology
The anterior cord syndrome is thought to have been initially described Schneider in 1955 in the English literature ref although there are reports of this being described by K Beck in German literature in 1952 4.
Most common CNS infection in HIV patients.
Caused by Toxoplasma gondii.
Reservoir in CATS.
3 Manifesations:
Congenital: meningitis, encephalitis, calcifcation, chorioretinitis, atrophy.
Immunocompetent: Systemic disease with LAD, fever, no CNS involvement.
Immunocomprimised : Fulminant CNS disease. Basal ganglia, Corticomedullary junction. solitary or multiple ring enhancing lesions with marked surrounding edema. Eccentric target appearance. After treatment lesions may calcify or haemorrage.
CNS FUNGAL INFECTIONS
2 presentations
Helpful features of
4 types of CNS fungal infections.
- Presentation:
- Basilar meningitis
- intense contrast enhancement of basilar meninges (similar to TB).
- Abscesses
- early -> granuloma.
- Late -> abscess with ring enhancement and central necrosis
- Basilar meningitis
- Helpful features of 4 different infections:
-
Aspergillosis (case in pictures)
- haemorragic infarcts from vascular invasion
- Often co-existant sinus disease that has extended to CNS
- T2 iso/hypointense mass like lesions
-
Mucormycosis
- Indistinguishable from aspegiliosis
-
Coccidioidomycosis
- Indistinguishable from TB
-
Cryptococcosis
- Cystic lesions
- Gelatinous pseudocysts secondary to spread into perivascular spaces in BG.
- Consider this diagnosis in an HIV +ve patient with communicating hydrocephalus
- Lacunar infarct like appearance in an HIV positive patient may be secondary to cryptococcal gelatinous pseudocysts.
- Cystic lesions
-
Aspergillosis (case in pictures)
There is a well defined, brilliantly enhancing round lesion is noted in the left lung suggestive of pulmonary arteriovenous malformation.
Incidentally noted a large haemangioma is the superior segments of liver.
Imaging features are most likely suggestive of Osler-Weber-Rendu syndrome.
Hereditary haemorrhagic telangiectasia
Dr James Harvey and Associate Professor Donna D’Souza◉ et al.
Hereditary haemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare inherited disorder characterised by abnormal blood vessel formation in the skin, mucous membranes, and organs including the lungs, liver, and central nervous system.
Epidemiology
Worldwide prevalence ~1.5 per 100,000. Wide geographic variability with a much higher incidence in certain regions, e.g. 1 in 200 in Dutch Antilles, 1 in 3500 in France.
Clinical presentation
Although the disease has a broad clinical spectrum, the classic clinical triad at presentation is epistaxis, multiple telangiectasias, and positive family history.
The diagnosis is a clinical diagnosis (Curacao criteria) based on the presence of 3 out of 4 of the following 8,9:
recurrent spontaneous epistaxis
multiple mucocutaneous telangiectasias
characteristic sites include: oral cavity, lips, fingers and nose
visceral AVMs
first degree relative with HHT
Pathology
It is an autosomal dominant multi-organ vascular dysplasia, characterised by multiple arteriovenous malformations (AVMs) that lack an intervening capillary network. Telangiectasias (small superficial AVMs) are particularly common. Mutations have been found in one of several genes (three known so far). De novo mutations are rare, almost all have a first-degree relative affected.
Hereditary haemorrhagic telangiectasia can involve multiple organ systems. The spectrum includes:
nasal: 90%
telangiectasias of nasal mucosa
complications: recurrent epistaxis
skin and mucosal membranes: 90%
telangiectasias of skin, oral cavity, conjunctivae
complications: recurrent bleeding
liver: 71-79% 5,7
symptomatic liver involvement in HHT is uncommon but does occur; it has been attributed to three distinct clinical subtypes and is believed to be a consequence of the predominant hepatic shunt pattern 2
high-output cardiac failure
shunting that increases cardiac preload
typically arteriovenous or portovenous shunts
portal hypertension
increased flow into the portal system (arterioportal shunt)
hepatic anatomic abnormalities leading to increased intrahepatic resistance
biliary disease
shunting of the blood away from the peribiliary plexus (arteriovenous or arterioportal shunting)
extensive arteriovenous shunting lead to biliary necrosis and bile leak
complications: hepatomegaly, right upper quadrant pain, high-output cardiac failure, portal hypertension, mesenteric angina from steal phenomenon
gastrointestinal tract: 20-40%
AVMs or angiodysplasia in the stomach, small bowel or large bowel
complications: recurrent GI bleeding
pulmonary: 20%pulmonary arterio-venous malformations (AVMs)
36% of patients with solitary pulmonary AVM have HHT
57% of patients with multiple pulmonary AVMs have HHT
complications
pulmonary haemorrhage, haemoptysis (less common)
complications of shunting (more common): paradoxical emboli (due to right to left shunt, e.g. stroke), septic emboli (e.g. cerebral abscess), hypoxaemia, high-output cardiac failure 9
CNS: 5-10%
cerebral AVMs, spinal AVMs or cerebral aneurysms
complications: headache, seizures, paraparesis, haemorrhage
one-third of cerebral complications in HHT are due to cerebral AVMs or aneurysms, and two-thirds are due to paradoxical emboli from pulmonary AVMs
increased incidence of capillary telangiectasia and developmental venous anomalies
Radiographic features
Imaging of visceral arteriovenous malformations
lung
chest x-ray: well-circumscribed mass (may be lobulated) with enlarged draining vein
CT: well-circumscribed vascular mass with enhancing feeding artery and draining vein
contrast echocardiography
presence of contrast bubbles in the left atrium confirms the presence of a shunt
characteristically, this occurs late (after several cardiac cycles), indicating a pulmonary shunt rather than intracardiac shunt
CNS
MR: cerebral and cerebellar AVMs typically in superficial locations
gastrointestinal tract
CT/CTA
conventional angiography
endoscopy
capsule endoscopy
nuclear medicine GI bleed study for active bleeding
liver
CT/CTA
MRI
conventional angiography
ultrasound
Treatment and prognosis
Treatment of visceral lesions
lung
embolisation; recanalisation occurs in up to 20% post embolisation
surgical resection
CNS
embolisation
surgical resection
stereotactic radiosurgery
gastrointestinal tract
embolisation
surgical resection
endoscopic ablation/electrocautery
liver
embolisation
surgical resection
liver transplantation
Prognosis
most patients have a normal life expectancy
10% die of complications: usually stroke, cerebral abscess or massive haemorrhage
Variant Cruetzfeldt-Jakob Disease
- A, Normal FLAIR image at the level of the basal ganglia shows the thalamus is normally isointense or slightly hypointense relative to the putamen. This appearance is depicted with most sequences, particularly the FLAIR sequence.
- B, Pulvinar sign of vCJD. FLAIR image shows marked, symmetrical hyperintensity of the pulvinar (posterior) thalamic nuclei. In this case, the pulvinar signal intensity was scored as grade 4 by both observers.
- C, “Hockey-stick” sign of vCJD. FLAIR image shows symmetrical pulvinar and dorsomedial thalamic nuclear hyperintensity. This combination gives a characteristic “hockey-stick” appearance and was present in 93% of cases with FLAIR imaging
- Collie, D., Summers, D., Sellar, R., Ironside, J., Cooper, S., Zeidler, M., Knight, R. and Will, R., 2020. Diagnosing Variant Creutzfeldt-Jakob Disease With The Pulvinar Sign: MR Imaging Findings In 86 Neuropathologically Confirmed Cases. [online] American Journal of Neuroradiology. Available at: http:> [Accessed 26 September 2020].</http:
Meningiomas
- origin
- age
- gender
- location
- association
- incidence
- 3 types
- origin
- Arachnoid Cap cells
- Age:
- 40-60 year old
- gender
- Female to male 3:1
- Incidence
- 30% of all brain tumors
- Associations
- NF2
- Types
- Typical ‘benign’ meningioma 93%
- Atypical meningioma 5%
- Anaplastic meningioma ‘Malignant’ 2%
Wernicke’s
- Case 1 Discussion
- Periaqueductal T2 hyperintensity involving the quadrigeminal plate.
- T2 hyperintensity of the mammillary bodies.
- No restricted diffusion. No contrast enhancement. No signs of infarction or inflammation.
- The patient presented with symptoms of ataxia, nystagmus and vertical gaze palsy. The patient was awake, NIHSS = 0, although disorientated to time and space. The additional neuropsychological testing revealed no hallucinations or delusions, but a mild amnestic syndrome with antegrade and retrograde deficits. Events of the last few days were not correctly remembered.
- The patient underwent bariatric surgery 2 months before presentation (sleeve-gastrectomy) which led to the neurological deficits in this case of thiamine deficiency-induced Wernicke encephalopathy.
- Laboratory results showed thiamine (vitamin B1) deficiency (13.5 ng/mL, normal: 20-100 ng/mL) and folate deficiency (0.8 ng/mL, normal: 4.6 - 18.7 ng/mL).
- The MRI shows some typical signs of Wernicke encephalopathy in this non-alcoholic patient: FLAIR/T2 - hyperintensity periaqueductal involving the quadrigeminal plate and hyperintensity of the mammillary bodies.
- The patient was treated with supplementary vitamins and folate and recovered within 2 weeks
- .
- Case 2 Discussion
- Bilateral mammillary body signal abnormality with contrast enhancement.
- Mildly increased FLAIR signal around the cerebral aqueduct.
- There is an incidental small colloid cyst within the foramen of Monro
- Wernicke encephalopathy is related to thiamine deficiency and is associated with excessive alcohol intake. Classic imaging features include symmetrical increased T2/FLAIR signal involving the mammillary bodies, and can also involve the dorsomedial thalami, tectal plate, periaqueductal area, and around the third ventricle.
- The usual clinical presentation is with the triad of confusion, ataxia, and ophthalmoplegia.
- capillary telengiectasia
- nests of dilated capillaries with normla brain interspersed between dilated capilaries
- commonly co-exist with cavenous malformations
- Locations
- pons>cerebral cortex > spinal cord> other locations
- Imaging
- CT is often normal
- MRI = foci of increased sig nal on Gd studdies
- low T2 if Hx has occured
- Angio may be normal or show a fain vascular stain
CNS capillary telangiectasia
Dr Daniel J Bell◉ and Dr Yuranga Weerakkody◉ et al.
CNS capillary telangiectasiae(s) are small, asymptomatic low flow vascular lesions of the brain.
Epidemiology
As these lesions are asymptomatic, diagnosis usually matches the age of first imaging with MRI, and as such are most frequently found in middle-aged and elderly adults. Their incidence varies according to the series. They can account for up to ~20% of all intracerebral vascular malformations on autopsy studies 2 and are considered the second most common vascular anomaly after venous angiomas (developmental venous anomaly) on imaging 5.
Clinical presentation
The vast majority of capillary telangiectasias are completely asymptomatic and discovered incidentally on MRI when the brain is imaged for other reasons.
Occasionally there may be associated intracerebral haemorrhage, although a direct causative relationship has not been established beyond a doubt. This may be more common with cases of mixed histology.
Pathology
They are comprised of dilated capillaries and are interspersed with normal brain parenchyma with a thin endothelial lining but no vascular smooth muscle of elastic fibre lining. This is in contrast to cavernous malformations (CM) which have no normal brain within their confines. Histology can be mixed with a component of CM.
Location
most occur in the pons, cerebellum and spinal cord
Associations
Osler-Weber-Rendu syndrome
Radiographic features
Capillary telangiectasias are mostly located in the brainstem (especially the pons). They are more often solitary, but sometimes can be multiple. They have only become widely recognised in the radiology community following the introduction of MRI, as they are usually not seen on CT and DSA 2-5.
MRI
They appear as subtle lesions with no mass effect.
T1: typically iso to low signal compared with brain parenchyma
T2: normal or slightly increased signal intensity
FLAIR: normal or slightly increased signal intensity
T2*: low signal intensity
thought to be due to deoxyhaemoglobin from sluggish flow, not haemorrhage 2
T1 C+:
may demonstrate stippled enhancement
if large, can show branching/linear draining veins
Treatment and prognosis
These lesions are almost always asymptomatic, have interspersed normal brain tissue and are most frequently located in the pons, making treatment impractical and unwarranted. Thus, no follow-up is required if the imaging appearances are characteristic.
Differential diagnoses
In the majority of cases, no differential needs to be entertained. When appearances are atypical then depending on the actual appearance, one could consider:
enhancing mass (usually mass effect present)
glioma
metastasis
resolving infarct
demyelination
cerebritis
vascular malformation
cavernous malformation
arteriovenous malformation (AVM)
developmental venous anomaly (DVA)
See also
radiation-induced vasculopath
WHAT IS THIS?
- BURNT OUT MENINGIOMA
- a term used to describe a meningioma that is completely calcified/ossified
- Indolent
- Likely to be a Psammomatous meningioma which is far more common than the other calcified type:
- Metaplastic Osseous MEningioma
- Usually in the ACF or MCF
- Fibrotic with few tumor cells.
- But look for the non-calcified portion of the Tumour as this has malignant potential.
This sagittal T1-weighted MR image shows a suprasellar lesion in a 12 year-old boy. There is a fat-containing area and a cystic area. There was minimal soft tissue component. The lesion expanded and remodelled the sella, without bone erosion. There is elevation of the optic chiasm, and the pituitary can be seen compressed into the base of its fossa.
Case Discussion
The lesion was biopsied. There were epithelial elements, underlying connective tissue with sebaceous glands, and fat, consistent with a mature teratoma. There were no immature or malignant components.
Intracranial teratomas are midline tumours which may contain calcium, soft tissue, cysts and fat. They occur from the optic chiasm to pineal regions. They may be mature, immature or malignant, depending on the degree of differentiation. Differential diagnoses include craniopharyngioma, dermoid and non-germinoma germ cell tumour.
OLIGODENDROGLIOMA
- INTRO
- Well-differentiation, slowly growing but diffusely infiltrating cortical, subcortical
- EPID
- 5-10% of primary intracranial neoplasms
- Seizures, headaches, focal neurological deficits most common.
- Peak 30-40years old
- Median survival time 10 years
- Loss of heterozygosity from 1p, 19q is associated with more favorable prognosis and better chemo response
- IMAGING
- Most common site is the frontal lobe (50-60%)
- partially CA++ subcortical/cortical frontal mass in middle aged adult is best diagnostic clue.
- typically T2 heterogenous, hyperintense mass
- Cystic/soloid
- cortex/subcortical
- May cause pressure erosion of calvaria
- 50% enhance, typically heterogenously.
- DDX
- Anaplastic oligodendroglioma (AO)
- Low-grade diffuse astrocytoma
- Ganglioglioma
- DNET
- PXA
- Cerebritis
- Cerebral ischaemia
- PATHOLOGY
- WHO II
- Anaplastic oligodendrolioma: WHO III
- 2016: now grouped with diffuse astrocytic tumours
- often a/w IDH mutations
Cerebral fat embolism
- Presentation
- Sickle cell patient. History of bone infarct.
- Presentation
- Case Discussion
- Case contributed by Dr Kauv Paul
- Diffuse and tiny foci of susceptibility artifact. No restricted diffusion.
- Very important small regions of susceptibility artifact (more than a 100) leading to the diagnosis of cerebral fat embolism. Especially with a history of bone infarct which is the aetiology of embolism rather than bone fracture as usual. This patient had sickle cell disease with cerebral fat embolism that should evoke bone infarct.
- Those lesions are visible in T2*, but better with SWI
- Differential are amyloid angiopathy or chronic hypertensive encephalopathy but those haemorrhagic lesions are bigger and fewer.
Cerebral fat embolism
- Author:
- Dr James Harvey and Dr Yuranga Weerakkody◉ et al.
- Intro:
- Cerebral fat embolism is one manifestation of fat embolism syndrome.
- Epidemiology
- Cerebral fat embolism typically occurs in patients with bony fractures (usually long bones of the lower limb). Rarely it has been described as part of a sickle cell crisis with bone marrow fat necrosis and subsequent embolism 4.
- Clinical presentation
- Cerebral manifestations of fat embolism syndrome can be highly variable and non-specific: the symptoms spectrum includes headache, lethargy, irritability, delirium, stupor, convulsions, or coma. Most cases can occur as subclinical events. Concurrent pulmonary or cutaneous features may aid in diagnosis.
- Pathology
- Fat emboli usually reach the brain through either right-to-left cardiac shunt or through an intact pulmonary circulation in those without a shunt 3.
- Radiographic features
- CT
- The CT brain can be normal in most cases 8. There may be evidence of diffuse oedema with scattered low-attenuating areas and haemorrhage in some situations.
- MRI
- T2: may show multiple non-confluent areas of high signal intensity
- DWI: may show bright spots on a dark background (starfield pattern) corresponding to the region of T2 signal abnormality.
- SWI: may distinctly demonstrate multiple minute hypointense foci in the brain 12-13
- T1: corresponding focal regions may show low T1 signal 9
- CT
- Differential diagnosis
- A differential to consider for the starfield pattern on MRI includes many other causes of multiple small foci of infarction or haemorrhage, although generally, only fat emboli will result in the very large number of tiny lesions characteristic of a starfield appearance. Other diagnoses to consider 6:
- diffuse axonal injury
- cardiogenic cerebral emboli or septic cerebral emboli
- cerebral vasculitis
- minute haemorrhagic cerebral metastases
- A differential to consider for the starfield pattern on MRI includes many other causes of multiple small foci of infarction or haemorrhage, although generally, only fat emboli will result in the very large number of tiny lesions characteristic of a starfield appearance. Other diagnoses to consider 6:
Note the multiple sites of oedema and haemorrhage, involving the brain stem and corpus callosum as well as subcortical white matter and left cerebral peduncle. High FLAIR signal is also seen in the dorsal midbrain. EVD insitu.
Case Discussion
Diffuse axonal injury can be subtle on CT but have devastating consequences for the patient. This is a case of grade III injury (involvement of brainstem) and carries a poor prognosis.
Diffuse axonal injury
Dr Jay Gajera◉ and Assoc Prof Frank Gaillard◉◈ et al.
Diffuse axonal injury (DAI), also known as traumatic axonal injury (TAI), is a severe form of traumatic brain injury due to shearing forces. It is a potentially difficult diagnosis to make on imaging alone, especially on CT as the finding can be subtle, however, it has the potential to result in severe neurological impairment.
The diagnosis is best made on MRI where it is characterised by several small regions of susceptibility artifact at the grey-white matter junction, in the corpus callosum, and in more severe cases in the brainstem, surrounded by FLAIR hyperintensity.
Epidemiology
The patients at risk of diffuse axonal injury belong to the same cohort as those who suffer traumatic brain injury and as such young men are very much over-represented.
Clinical presentation
Typically, patients who are shown to have diffuse axonal injury have loss of consciousness at the time of the accident. Post-traumatic coma may last a considerable time and is often attributed to coexistent more visible injury (e.g. cerebral contusions). As such the diagnosis is often not suspected until later when patients fail to recover neurologically as expected.
Pathology
Diffuse axonal injury is the result of shearing forces, typically from rotational acceleration (most often a deceleration). Due to the slightly different specific gravities (relative mass per unit volume) of white and grey matter, shearing due to change in velocity has a predilection for axons at the grey-white matter junction, as the name implies. In the majority of cases, these forces result in damage to the cells and result in oedema. Actual complete tearing of the axons is only seen in severe cases. It is also known that some neurones may undergo degeneration in the weeks or months after trauma, it is called secondary axonotmesis.
Associations
intermediary injuries
Radiographic features
Diffuse axonal injury is characterised by multiple focal lesions with a characteristic distribution: typically located at the grey-white matter junction, in the corpus callosum and in more severe cases in the brainstem (see: grading of diffuse axonal injury).
CT
Non-contrast CT of the brain is routine in patients presenting with head injuries. Unfortunately, it is not sensitive to subtle diffuse axonal injury and as such, some patients with relatively normal CT scans may have significant unexplained neurological deficit 4,5.
The appearance depends on whether or not the lesions are overtly haemorrhagic. Haemorrhagic lesions will be hyperdense and range in size from a few millimetres to a few centimetres in diameter. Non-haemorrhagic lesions are hypodense. They typically become more evident over the first few days as oedema develops around them. They may be associated with significant and disproportionate cerebral swelling.
CT is particularly insensitive to non-haemorrhagic lesions (as defined by CT) only able to detect 19% of such lesions, compared to 92% using T2 weighted imaging 4. When lesions are haemorrhagic, and especially when they are large, then CT is quite sensitive. As such, it is usually a safe assumption that if a couple of small haemorrhagic lesions are visible on CT, the degree of damage is much greater.
MRI
MRI is the modality of choice for assessing suspected diffuse axonal injury even in patients with entirely normal CT of the brain 5,6. MRI, especially SWI or GRE sequences, exquisitely sensitive to paramagnetic blood products may demonstrate small regions of susceptibility artefact at the grey-white matter junction, in the corpus callosum or the brain stem. Some lesions may be entirely non-haemorrhagic (even using high field strength SWI sequences). These will, however, be visible as regions of high FLAIR signal.
Over the first few days, the degree of surrounding oedema will typically increase, although by 3-months post-injury FLAIR changes will have largely resolved 7. In contrast, SWI changes will usually take longer to resolve, although by 12-months post-injury there will have been substantial resolution 7. This is to be expected as oedema is faster to resolve than haemorrhage.
In the months that follow the trauma, there is accelerated brain volume reduction, which can sometimes be detected by visual inspection, but sometimes only by volumetric studies8.
Importantly, it should be noted, that even with high field strength modern scanners, the absence of findings does not categorically exclude the presence of axonal injury.
MR spectroscopy
MRS can be of benefit in identifying patients with grade I injury which may be inapparent on other sequences. Features typically demonstrate elevation of choline peak and reduction of NAA 3.
Treatment and prognosis
Unfortunately little can be done for patients with diffuse axonal injury other than providing supportive care trying to minimise secondary damage caused by cerebral oedema, hypoxia, seizures, etc. Management involves the early recognition and treatment of neurosurgical complications such as herniation and hydrocephalus.
Depending on the severity and distribution of injury (see: grading of diffuse axonal injury) patients can vary from minimally affected to be in a persistent vegetative state 1,2. The amount of axonal injury in the brainstem is predictive of long-term vegetative state, whereas supratentorial injury can result in focal neurological or neuropsychiatric deficits 1.
Differential diagnosis
On imaging consider:
cortical contusions
the main differential in patients with head injuries
typically located superficially, involving the cortex (rather than at the grey-white matter junction) and are usually associated with variable amounts of extra-axial blood (subarachnoid and subdural)
diffuse vascular injuries
particularly on T2* sequences
amyloid angiopathy
chronic hypertensive encephalopathy
cavernoma type IV
Pilocytic Astrocytoma
- INTRO
- 1 of 4 of the localised types of astrocytic Tumoursf
- most common in kids
- 30% of pediatric gliomas
- 2nd most common pediatric Brain Tumour
- Indolent and slow-growing
- Location
- cerebellum > Optic Chiasm > brain stem > hypothal
- Rad features
- In the cerebellum it looks cystic with enhancing mural nodule.
- Calc in 10%
- Optic chiasm/hypothalamus are solidly enhancing
- Brainstem: little enhancement
- In the cerebellum it looks cystic with enhancing mural nodule.
- Focal tumours localised to the TECTUM = tectal Gliomas and constitute a distinct group of brain stem gliomas.
- The term pilocytic refers to the elongated hair-like projections from the neoplastic cells. The presence of eosinophilic Rosenthal fibres is a characteristic feature and hyalinization of blood vessels is also common. The histological features are however, fairly heterogeneous even within the one tumour, with some areas mimicking diffuse astrocytomas and even oligodendrogliomas 6.
- pilocytic: Made up of cells that look like fibers when viewed under a microscope.
*
Order of progression of brain myelination pattern?
- Order of progression
- just remember
- inferior to superior
- posterior to anterior
- central to peripheral
- Sensory prior to motor
- just remember
- THE SUBCORTICAL HITE MATTER IS THE LAST PART OF THE BRAIN TO MYELINATE
- THE THE OCCIPITAL WHITE MATTER AROUND 12MONTHS
- and the frotnal regions finishion around 18 m onths
- The ‘terminal zones’ of myelination occur in the subcortical frontotemporaopariertal regions around 40 months.
- The brain stem and posterior limb of the internal capsule are normally myelinated at birth.
NEUROSARCOID
- Central nervous system involvement by sarcoidosis, also termed neurosarcoidosis, is relatively common among patients with systemic sarcoidosis and has a bewildering variety of manifestations, often making diagnosis difficult.
- Epidemiology
- The demographics of affected patients is similar to that of systemic sarcoidosis, typically affecting patients 30-40 years of age with a female predilection 2.
- Clinical presentation
- Central nervous system involvement by sarcoidosis is very variable, with lesions potentially involving the leptomeninges, pituitary and parenchyma of all parts of the intracranial compartment. Thus, clinical presentation is also very variable and nonspecific:
- signs and symptoms of raised intracranial pressure due to hydrocephalus
- cranial nerve palsies
- optic nerve involvement (particularly common) 5
- facial nerve palsy
- endocrine features of hypothalamic/pituitary sarcoidosis 7
- diabetes insipidus
- SIADH
- hyperprolactinaemia
- hypothyroidism
- hypoadrenalism
- seizures
- variable weakness, paraesthesias and dysarthria/dysphagia
- spinal cord involvement presenting as myelopathy 5
- Central nervous system involvement by sarcoidosis is very variable, with lesions potentially involving the leptomeninges, pituitary and parenchyma of all parts of the intracranial compartment. Thus, clinical presentation is also very variable and nonspecific:
- Although it is very rare (range 1-17% 1,6) to have isolated neurosarcoidosis (i.e. without systemic disease), central nervous system symptoms are not uncommonly the first manifestation, and as such patients are often imaged without the diagnosis of systemic sarcoidosis having yet been made.
- Interestingly up to 10% of patients with the systemic disease will demonstrate positive imaging findings; thus not all patients with demonstrable imaging findings of neurosarcoidosis are symptomatic.
- Pathology
- Histologically, central nervous system involvement is seen in ~20% (range 14-27%) of patients with systemic sarcoidosis, although only ~10% (range 3-15%) are symptomatic 1-3.
- Radiographic features
- The radiographic features of neurosarcoidosis can be thought of as occurring in one or more of five compartments. From superficial to deep they are:
- skull vault involvement (refer to musculoskeletal manifestations of sarcoidosis)
- pachymeningeal involvement
- leptomeningeal involvement (seen in up to 40% of cases 1)
- pituitary and hypothalamic involvement
- cranial nerve involvement
- parenchymal involvement (most common)
- Intracranial dermoid cysts
- uncommon
- characteristic appearances on imaging
- well defined
- lobulated
- midline mass
- Fat density
- High signal on T1
- no enhancement
- Epidemiology
- F>M
- 0.5% of primary Intracranial tumours
- 30yo<
- Spectrum with
- EPIDERMOID cysts at one end
- contain ONLY desqumated sqaumous epithelium
- TERATOMAS at the other end
- containing ANY kind of tissue from ALL three embryonic tissue layers
- EPIDERMOID cysts at one end
- Clinical Presentation
- Mass effect
- Rupture
- leakage of sebum into the SAS -> aseptic chemical meningitis
- Case courtesy of Dr Hani Makky Al Salam, Radiopaedia.org, rID: 8321
- Left middle cranial fossa cystic lesion with high signal on T1 and T2, thin regular marginal enhancement and complete suppression on T1 fat sat post-contrast sequence.
High T1 foci along brain sulci (subarachnoid space) notably along adjacent left Sylvian fissure, consistent with rupture.
Mild communicating hydrocephalus is also noted.
- Large left middle cranial fossa hypodense cystic lesion with smooth margins and linear calcifications. Minute hypodense foci are seen along subarachnoid spaces (sulci) of both cerebral hemispheres, consistent with rupture.
Mild communicating hydrocephalus is noted.
Case Discussion
Features are consistent with ruptured intracranial dermoid cyst.
MRI Appearance of ICH
hyper Acute
acute
Early sub acute
late subacute
chronic
- I bleed, I die, Bleed die, Bleed bleed, Die die
- hyper Acute (case 1)
- 1 day
- IB
- T1 iso
- T2 Bright
- intracellular Oxy Hb
- acute
- 1-3 days
- ID
- T1 Iso
- T2 Dark
- intracellular Deoxy Hb
- Early sub acute
- 2-7 days
- BD
- T1 Bright
- T2 Dark
- Intra cellular Met Hb
- late subacute
- 7-14days
- BB
- T1 Bright
- T2 Bright
- extra cellular Met Hb
- over the next few weeks, as cells break down, extracellular methaemoglobe leasds to an increase in T2 Sig.
- chronic
- >14 days
- DD
- T1 dark
- T2 Dark
- intra cellular Haemosiderin peripherally
- centre extracellular haemichronics T1 I, T2 B.
Haemorrhage on MRI
Dr Yuranga Weerakkody◉ and Assoc Prof Frank Gaillard◉◈ et al.
Haemorrhage on MRI has highly variable imaging characteristics that depend on both the age of the blood, the type of haemoglobin present (oxy- deoxy- or met-), on whether or not the red blood cell walls are intact and the specifics of the MRI sequence. Although MRI is often thought of as not being sensitive to acute haemorrhage, this is not, in fact, true particularly with more modern sequences 5,7.
The appearance of haemorrhage will, however, be different at different times and is not perfectly stereotyped, as such caution should be exercised in precisely ageing haemorrhages.
On this page:
Article:
Physiology
Stages
Practical points
References
Images:
Cases and figures
Physiology
The factors that affect the appearance of haemorrhage on MRI vary according to the sequence. The oxygenation state of haemoglobin and the location of either contained within red blood cells or diffused in the extracellular space have a tremendous effect on the imaging effects of blood. The three haemoglobin states to be considered are oxyhaemoglobin, deoxyhaemoglobin and methaemoglobin.
Oxyhaemoglobin, accounting for 95% of haemoglobin in arterial blood and 70% in venous blood, is only weakly diamagnetic, having little T2* and only mildly shortening T1 relaxation time 2,6. This is the result of haem iron is in ferrous form (Fe2+) and has no unpaired electrons 2.
Deoxyhaemoglobin, in contrast, having lost oxygen has four unpaired electrons and is strongly paramagnetic and results in substantial signal loss on T2* weighted sequences, such as susceptibility weighted imaging, and blooming artefact 2.
Methaemoglobin results from oxidative denaturation of the haem molecule to the ferric (Fe3+) form has five unpaired electrons is also strongly paramagnetic 2.
T1 weighted sequences
Oxyhaemoglobin and deoxyhaemoglobin produce little effect on T1 signal. The presence of blood proteins results in intermediate T1 signal in hyperacute and acute haemorrhages.
T2* weighted sequences
T2* weighted sequences, such as susceptibility weighted imaging and gradient echo are primarily affected by the haemoglobin oxygenation state and whether or not cell lysis has occurred 2.
While contained within red blood cells, resulting in uneven distribution of paramagnetic effects, both deoxyhaemoglobin and methaemoglobin result in signal loss. Once the cells lyse and methaemoglobin is distributed evenly throughout the clot, the local magnetic field distortion is also lost and T2 signal loss fades 2.
Eventually, haemosiderin and ferritin (both paramagnetic) are then ingested by monocytes and macrophages and results once more in unevenly distributed paramagnetic effects and signal loss 2.
Diffusion-weighted imaging
Apparent diffusion coefficient (ADC) maps demonstrate fairly stable values substantially lower than normal white matter in all stages except for chronic (see below), whereas isotropic/trace DWI images, due to them combining T2 and diffusion effects, demonstrated high signal only on hyperacute and late subacute phases 8.
Stages
In general, five stages of haematoma evolution are recognised:
hyperacute (<1day)
intracellular oxyhaemoglobin
isointense on T1
isointense to hyperintense on T2
high signal on isotropic DWI and reduced ADC values 8
acute (1 to 3 days)
intracellular deoxyhaemoglobin
T2 signal intensity drops (T2 shortening)
T1 remains intermediate-to-low
low signal on isotropic DWI and reduced ADC values 8
early subacute (3 to 7 days)
intracellular methaemoglobin
T1 signal gradually increases (T1 shortening) to become hyperintense
low signal on isotropic DWI and reduced ADC values 8
late subacute (7 to 14-28 days)
extracellular methaemoglobin: over the next few weeks, as cells break down, extracellular methaemoglobin leads to an increase in T2 signal
high signal on isotropic DWI and reduced ADC values 8
chronic (>14-28 days)periphery
intracellular haemosiderin
low on both T1 and T2
centre
extracellular haemichromes
isointense on T1, hyperintense on T2
low signal on isotropic DWI and increased ADC values 8
Remembering these may be facilitated by this ageing blood on MRI mnemonic.
Practical points
extracranial blood products age differently from intracranial blood products, and extracranial haematomas often have a heterogeneous appearance, confounding attempts at reliably dating the age of an extracranial haemorrhage 3,4
subacute and chronic blood appears hypointense and blooms on MRI T2* weighted sequences (e.g. susceptibility weighted imaging (SWI))
presence of blood products in a cavity will result in low ADC values and therefore make use of diffusion restriction to diagnose pus in an abscess useless
Presentation
75 year old woman with dementia.
Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org. From the case rID: 10674
Vascular dementia
Case Discussion
MRI demonstrates prominent deep white matter T2 hyperintensity with resultant central volume loss. There is no lobar atrophy, suggesting the dementia is likely due to multiple white matter infarcts.
Intra Vs Extra-axial tumours
- INTRA
- YES CSF SPACES EFFACED
- YES G/W matter junction Destruction
- NO not continuous with bone/falx
- NO bone changes
- NO Corticomedullary buckling
- VASCULAR supply internal
- Extradural
- YES contiguous with bone/falx
- YES bone changes
- CSF spaces widened
- CM buckling YES
- G/W Matter junction is preserved
- Vascular supply is external/Dural Branches.
Cause
epid
source
Presentation
Rx
- Caused by:
- pork tap worm
- taenia solium
- Epid
- central and south america
- Hispanic Population
- Source
- Contaminated water or pork
- eggs penetrate intestine
- haematogenous spreach
- encyst in muscle, brain and eyes
- Cyst contain living larvae
- dies
- inflammation causing contrast enhancement and calcification
- non-enhancing cyst => live larvae
- Calc => old lesion.
- enhancing => dying/dead larvae with inflammation.
- Presentation
- seizure
- Rx
- praziquantel albendazole
- VP shunt
-
4 localized Astrocytic tumors
- Pilocytic astrocytoma
- A/W NF1
- WHO grade 1
- cerebellum (cystic with mural nodule)
- optic chiasm, optic nerves and Hypothalamus are usually solidly enhancing and less well defined
- Pilomyxoid Astrocytoma
- Who Grade II
- Infants and young kids
- Suprasella or hypothal
- Haemorrhage is common
- Sub ependymal Giant cell astrocytoma
- WHO grade 1
- subependymal tumour growth along the caudothalamic groove
- A/W Tuberous Sclerosis
- Pleomorphic Xanthroastrocytoma
- WHO Grade II
- Typically P/W Temporal lobe epilepsy
- Creutzfeldt-Jakob disease (CJD)
- a spongiform encephalopathy that results in a rapidly progressive dementia and other non-specific neurological features and death usually within a year or less from onset. The vast majority are sporadic, but familial and acquired forms are also occasionally encountered.
- On imaging, it classically manifests as T2/FLAIR hyperintensities within the basal ganglia, thalamus, and cortex. These lesions show diffusion restriction on DWI/ADC sequences.
- Epidemiology
- Four types of Creutzfeldt-Jakob disease have been described 2,6:
- sporadic (sCJD)
- accounts for 85-90% of cases
- further divided into numerous subtypes according to molecular markers (see pathology section below)
- variant (vCJD)
- bovine-to-human transmission of bovine spongiform encephalopathy (a.k.a. “mad cow disease”): considered zoonotic by some
- especially if in the UK between 1981-1996
- subsequent human-to-human transmission (e.g. transfusion) of vCJD
- familial (fCJD)
- 10% of cases
- these individuals carry a PRPc mutation
- iatrogenic (iCJD)
- following administration of cadaveric human pituitary hormones (pre-1985)
- various transplants
- sporadic (sCJD)
- Four types of Creutzfeldt-Jakob disease have been described 2,6:
- SECOND CASE
- Multifocal areas of asymmetrical diffusion restriction involving the cortex of bilateral frontal, parieto-occipital and temporal lobes. This is associated with subtle T2/FLAIR hyperintensity. There is no obvious involvement of the white matter. No blooming artefacts on GRE images to suggest blood products.
- Case Discussion
- There are very few differential diagnosis of this disease pattern, and in the absence of an acute event and lack of any underlying known systemic disease, CJD is most likely. The diagnosis was confirmed by biopsy.
13 groups of
Types of primary brain tumors based on cell type/location
- GLIOMAS
- Astrocytic (80%)
- Local
- Pilocytic
- Pilomyxoid
- Subependymal Giant Cell astrocytoma
- Pilocytic Xanthroastrocytoma
- Diffuse
- Diffuse Astrocytoma
- Anaplastic Astrocytoma
- GBM
- midline glioma
- Local
- Oligodendromas (10%)
- Astrocytic (80%)
- EPENDYMAL
- Ependymoma
- Subependymoma
- CHOROID PLEXUS
- papiloma
- carcinoma
- MENINGIOMA
- MESENCHYMAL
- solitary fibrous tumour (hemangiopericytoma)
- hemangioblastoma
- Neuronal/mixed neuronal-glial
- ganglioglioma
- Gangliocytoma
- DNET
- central neurocytoma
- Germ cell tumours
- Germinoma
- teratoma
- mixed
- PINEAL
- Pineocytoma
- Pineoblastoma
- Pituitary
- micro/macroandenoma
- EMBRYONAL
- Medulloblastoma
- Retinoblastoma
- neuroblastoma
- ependymoblastoma
- Nerve sheath
- Schwannoma
- Neurofibroma
- Haematopoietic
- leukaemia
- lymphoma
- Tumour like
- dermoid
- lipoma
- hamartoma
Imaging features and stages of….
Neurocysticerosis
- Neurocysticercosis (NCC) is a neurologic infection caused by the larval stage of the tapeworm Taenia solium. In the developing world, NCC, infection of the central nervous system (CNS) with the T. solium larvae, is the most common cause of acquired epilepsy [1–3].
- Neurocysticercosis is a preventable parasitic infection of the central nervous system and is caused by the pork tapeworm Taenia solium. Humans become infected after consuming undercooked food, particularly pork, or water contaminated with tapeworm eggs, or through poor hygiene practices.
- small enhancing rim lesion with a peripheral enhancing nodule (SCOLEX).
- Can be large and obstruct CSF -> hydrocephalus.
- Can seed to the entire neuraxis
- Significant edema
- Calcifies.
- 4 stages
- 1: vesicular stage: thin walled vesicles <20mm with CSF like fluid and mural nodule. No inflam response.
- 2: Colloid stage: cyst dies. Cyst fluid becomes turbid. Inflammation and break down of the BBB.
- 3: Nodule granular stage. Lesion undergoes involusion and begins to calcify.
- 4 Calcified Stage:
- Location
- parenchymal
- interventricula
- subarachnoid
- other findings:
- hydrocephalus
- chronic meningits
- calcification of skeletal muscle (order an MRI/CT of thigh muscles).
CARBON MONOXIDE POISONING
- Radiographic features
- Changes tend to be bilateral with the globus pallidus most commonly affected 2.
- CT
- Classically seen as low attenuation in the globus pallidus region. Other features include diffuse hypoattenuation in cerebral white matter 4.
- MRI
- Regions of involvement are similar to CT. Signal characteristics include:
- T1: affected areas are usually low signal, haemorrhagic areas can be high signal
- T2/FLAIR: affected areas are high signal
- T1 C+ (Gd): can show patchy peripheral enhancement in affected areas in the acute phase 2
- DWI: affected areas show increased diffusion signal in the acute phase
- Regions of involvement are similar to CT. Signal characteristics include:
- Differential diagnosis
- CT
For involvement in and around the globus pallidus, consider:
mitochondrial encephalopathies: tends to affect other basal ganglia regions
Leigh disease
Kearns-Sayre syndrome
other toxic encephalopathies
cyanide neurotoxicity: tends to also affect the cortex
methanol neurotoxicity: tends to affect the putamen 7
organophosphate neurotoxicity
other causes of anoxia
metabolic disorders
Wilson disease
prion encephalopathies
Creutzfeldt-Jakob disease
Fusiform aneurysm
- fusiform aneurysm
- elongated aneyrsm casued by
- atheroscleorisis
- kmostly located in the vertebrobasilar system
- A/w
- dolichoectasisa
- Imaging fatures
- VB arteries are elongated, tortuous and dilated
- tip of basilar artery may indent 3rd vent.
- aneyrysm may be thrombosed
- bizarre flow voids bc turbulent flow
- Complcations
- brain stem infarct
- because of thrombus
- Mass effect
- Cn palsies
- elongated aneyrsm casued by
SAH
intro and causes
complications
what to do if you cant find a cause
which cns are effected most
- Intro
- blood in the SA space +/- vent
- 2ndary vasospasm and infection are the lading causes of death
- Causes
- Trauma
- Aneurysm 90% most common cause after trauma
- AVM, Dural AVF
- co-agulop
- extension of intraparenchyma hx (tumour, HTN)
- Amyloid
- RCVS
- Idiopathic
- spinal AVM
- Complications
- hydroceph 2ndary to obstruction/arachnoiditis
- vasospasm several days after sah may lead to infact
- leptomenigeal superfical siderosis secondary to iron depositing, secondary to chronic of recurrent SAH
- The location of the sidderosis corresponded to the extent of the central myelin
- CN I, II, VIII preferentially effectied bc they have a peripheral myelin envelope
- Other CNS have their transition poist closer to the brain stem
- if no causes is found MRI spine to look for a chronically bleeding spinal neoplasm
- ie epndymoma or paraganglioma
- perimesencephalic SAH is angiography negative
- from a venous bleed
AVM SPETZLER CRITERIA
- case in picture
- Large nidus of malformed vessels with serpigenous appearance (bag of worm) seen involving the right superior temporal and inferior frontal regions. Although large no mass effect could be detected. Arterial supply derived from the right posterior and middle cerebral arteries. venous drainage to the cortical veins and right internal cerebral vein. No haemorrhage could be detected. It displays flow void signal in T2 and SWI with homogenous contrast enhancement after contrast administration.
Case Discussion
Cerebral AVM may be parenchymal, dural or mixed according ot its arterial supply and venous drainage. The hallmark of the disease is the presence of nidus which is a large collection of arteries and veins that communicate with each others without capillary bed though arteriovenous shunting occur.
- Points system
- Eloqence
- positive 1
- neg 0,
- draining vein
- superfiical 0,
- deep 1
- Size
- <3cm 1,
- 3-6cm = 2,
- > 6cm 3
- Eloqence
- higher score is A/w increase risk of hx
- other poor prognostic factors
- intranidal aneurysm
- aneyrsym COW
- Aneysrym is a feeder
- VEnous stasis
- Complications
- Hx
- seizures
- Comulative risk hx is 3% / yr
Spetzler-Martin arteriovenous malformation grading system
Dr Daniel J Bell◉ and Assoc Prof Frank Gaillard◉◈ et al.
The Spetzler-Martin arteriovenous malformation (AVM) grading system allocates points for various angiographic features of intracranial arteriovenous malformations to give a score that predicts the morbidity/mortality risk of surgery.
Grading
The grade (denoted in Roman numerals) is equal to the sum of points in 3 categories, for a minimum of grade I and maximum of grade V (with a special designation of grade VI explained below) 1:
size of nidus
small (<3 cm) = 1
medium (3-6 cm) = 2
large (>6 cm) = 3
eloquence of adjacent brain
non-eloquent = 0
eloquent = 1
venous drainage
superficial veins only = 0
deep veins = 1
The size is defined by the largest diameter of the nidus on angiography.
The following areas are considered eloquent:
sensory, motor, language, or visual cortex
hypothalamus or thalamus
internal capsule
brainstem
cerebellar peduncles (superior, middle, or inferior)
deep cerebellar nuclei
The venous drainage pattern is considered deep if any of the drainage is to deep cerebral veins such as the internal cerebral vein, basal vein of Rosenthal, or precentral cerebellar vein. Cerebellar hemispheric veins are considered deep unless they drain directly into the straight sinus or transverse sinus. The presence of deep drainage complicates excision due to poor surgical accessibility compared to a malformation where all of the drainage is via the cortical venous system.
A special category, grade VI, is defined as “inoperable,” in which surgical resection would almost certainly cause total disability or death. At the time of the original grading system proposal, this category included diffuse nidus arteriovenous malformations that encompass eloquent brain structures.
History and etymology
The classification was proposed in 1986 by Drs Robert F Spetzler and Neil A Martin, both neurosurgeons at the Barrow Neurological Institute in Arizona, USA 1.
SPINAL CANAL and SPINAL CORD ANATOMY
- Spinal canal
- Vertebral elements
- body
- posterior elements
- neural ring
- posterior margin of vertebral body
- pedicles
- laminae
- articulr facets
- transverse processes
- Recesses
- subarticular recess
- lateral recess
- Components:
- Nucleus polposus (notochordal orign)
- annulus fibrosus with peripheral SHARPEY fibres
- CT density 60-120 HU.
- Disk periphery is slightly denser than is centre (Sharpy fibres calcify).
- Disk is much denser than the thecal sac (0.30HU)
- MRI
- T1: hypointernse relative to marrow
- PD/T2
- hyperintense relative to marrow with hypointense intranuclear cleft
- Ligaments
- ligamentum flavum
- attaches to lamina and facets
- PLL: raely seen by MRI ecept in herniations
- Thecal sac
- lined by dura and surrounded by epidural fat
- Normal AP adiameter of thecal sac
- Cx >7mm
- Lx >10mm
- MRI frequently shoes CSF flow artifacts in the thecal sac.
- ligamentum flavum
- NEURAL STRUCTURES:
- spinal cord
- AP diameter 7mm
- Conus medullaris: 8mm tip at L1-L2
- Filum terminale extends from L1 - S1
- Nerve roots
- Ventral root
- dorsal root
- DRG
- The dorsal and ventral nere roots join in the spinal canal to form the spinal nerve
- The nerve splits into ventral and dorsal rami and short distance after exiting the neural foramen
- Below T1
- spinal nerve courses UNDER the pedicle for which it is named ie L4 goes under the L4 pedicle
- Above T1
- spinal nerve courses above the pedicle for which it is named.
- Below T1
- nerve roots lie in the superior portion of the intevertebral neural foramen.
- spinal cord
- Vertebral elements
Congenital
CHIARI I
Clinical Findings:
- Intermittant compression of Brain-stem newve palsies
- Intermittant facial Pain Respiaratory depression long tract sign
Rad Findings
- Tonsilar hermiation, Syringo migelia, No Brain Anomalies
- Downward displacement of the cerebellar tonsils below the foramen. The 4th V maybe elongated but remains in a normal position.
- Chiari I is not a/w myelomeneningo sceles and is unrelated to CHIARI II & III.
- Presents @20~yo
Associations:
- syringchydromeyelia 50%
- loss of tendon reflexes
- weakners of hands and feet
- hydroceph 25%
- Basilar Invagination. Kipple Fell Syndrome: fusion of 2 or more cervical vertibres
- Atlantooccipital fusion
*
HIV encephalopathy
- WHAT
- Progressive subacute subcortical dementia secondary to HIV itself
- Eventually develops in 60% of AIDS patients
- HOW DOES IT LOOK?
- Atrophy
- Increased T2 WM lesions in frontal and occipital lobes and periventricular locations
- Gliosis + demyelination
- Sparing of the subcortical U-fibres
- no enhancement or mass effect of WM lesions
- Diffuse midline Gliomas
- INTRO
- 10-15% of paediatric Brain Tumours
- Most commonly involve the brain stem
- Pons > MB > medulla > spinal Cord > thalamus
- many exhibit mutations in histone H3 gene affecting the K27 exon
- CLINICAL FEATURES
- CN VI + VII neuropathy
- Long tract signs
- Hydrocephalus
- RAD FEATURES
- enlargement of the brain stem
- posterior displacement of the 4th ventricle
- the floor of the 4th ventricule should be in the middle of the TWINING LINE which is between the Tuberculum sella and the toucula.
- encasement of the basilar artery
- Cystic formation uncommon
- Hydrocephalus 30%
- Enhancement in 50% (patchy and variable)
- Exophyic extension into the basilar cysterns
- MIMICS
- brain stem encephalitis
- Demyelinating disease.
- Radiographic features
- In tumours located within the pons, the pons is enlarged with the basilar artery displaced anteriorly against the clivus and potentially engulfed.
- The floor of the fourth ventricle is flattened (“flat floor of fourth ventricle sign”) and obstructive hydrocephalus may be present.
- Occasionally the tumour is exophytic, either outwards into the basal cisterns or centrally in the 4th ventricle.
- Usually the tumour is homogenous pre-treatment, however in a minority of patients areas of necrosis may be present.
- CT
- Typically hypodense with little, if any, enhancement.
- MRI
- T1: decreased intensity
- T2: heterogeneously increased
- T1 C+ (Gd): usually minimal (can enhance post radiotherapy)
- DWI/ADC: usually normal, occasionally mildly restricted
- The extensive spread is relatively frequent, both craniocaudally to involve the cerebral hemispheres and spinal cord, as well as leptomeningeal spread 3.
- INTRO
Intro
Causes and imaging features
- Intro
- Infected fluid collection in subdural (common) or epidural (uncommon) locations
- Neurosurgical emergency
- Causes
- sinusitis (most common)
- otitis
- trauma
- Post craniotomy
- Imaging Features
- DWI restriction, low on ADC
- Subdural or epidural low attenuation fluid collection with enhancement of adjacent brain.
- Venous infarction -> edema -> masseffect -> midline shift
- Thick curvilinear enhancement of empyema
- Concominent signed of sinusitis/otits
Brain myelination
What are the signal characteristics of a baby’s brain cf to an adult?
- The baby brain has essentially the opposite signal characteristics as the adult brain
- The T1 pattern of a baby is similar to a T2 pattern of an adult.
- The T2 pattern of a baby is similar to the T1 pattern of an adult.
- This is secondary to myelination differences.
- Immature myelin has a higher water content relative to mature myelin and therefore is brighter on T2 and darker on T1.
- During the matruation process water will decrease and fat will increase.
- Therefore mature white matter will be brighter on T1 and darker on T1.
Extra-axial tumours/Tumour Like
- TUMOURS
- Meningioma
- Hemangiopericytoma
- Solitary fibrous Tumour
- Dural Mets
- Melanocytoma
- TUMOUR LIKE
- Erdheim Chester
- IgG4 disease
- Rosai-Dorfman
- Sarcoid
- TB
- Symphilis
Cytotoxic vs Vasogenic Oedema
- Cytotoxic Oedema
- Cellular Swelling due to ECF moving Intracellular space
- We use to describe the mechanism of which both DWI changes and established CT changes become apparent.
- vasogenic oedmea:
- Increased ECF in setting of abscess or tumour that has disrupted the BBB.
Anaplastic astrocytoma
- Intro
- 30 % of astrocytomas
- 40-60 year old
- Cerebral hemispheres
- Majority develop from lower grade Diffuse astrocytoma
- Rad Features
- Hererogenous mass
- calc uncommon
- edema common
- Enhancement reflects BBB disruption.
- Acquired hepatocerebral degeneration is an uncommon irreversible extrapyramidal neurodegenerative condition encountered in patients with cirrhotic chronic liver disease, resulting in widespread cerebral, basal ganglia and cerebellar damage.
- Terminology
- Acquired hepatocerebral degeneration is a term that is restricted to patients which cirrhotic liver disease resulting from a variety of causes but specifically excluding Wilson disease; in fact this condition is often termed acquired non-Wilsonian hepatocerebral degeneration to ensure the distinction is made.
- Acute neurological dysfunction from hyperammoniaema or other transient alterations in hepatic metabolism is termed hepatic encephalopathy and is discussed separately. Occasionally acquired hepatocerebral degeneration is referred to as chronic hepatic encephalopathy, although this is probably best avoided.
- Clinical presentation
- Patients with acquired hepatocerebral degeneration usually, but not always, have had multiple prior episodes of hepatic encephalopathy 6.
- They present with gradual neurological dysfunction including dementia, rigidity, dysarthria, gait ataxia, tremor and choreoathetosis 5.
- Pathology
- Although the pathophysiology of acquired hepatocerebral degeneration is uncertain, manganese overload is believed to be part of the disease and responsible for the T1 shortening observed in the globus pallidus 7.
- Radiographic features
- MRI
- T1
- intrinsic high signal intensity in the globus pallidus +/- subthalamic region, and midbrain (substantia nigra)1-5
- thought to be a reflection of increased tissue concentrations of manganese 1-4
- may reverse following liver transplantation 6
- T2
- increased signal in the middle cerebellar peduncles (MCP sign) 5
- T1
- MRI
Huntington Disease
Huntington disease is a hereditary neurodegenerative disease (autosomal dominant trait, but often de novo mutations), and can present with early onset dementia as well as choreoathetosis and psychosis.
Imaging shows characteristic atrophy of the caudate nucleus and subsequent enlargement of the frontal horns of the lateral ventricles.
Fetal orgin of the PCA
- Most common vascular variant (propbably) 30% of the population.
- The PCA is fed primarily as an anterior circ artery (occipital lobe is fed by the ICA).
- Therefore the PCOM is large (some people define it as larger than P1.
- Anatomy with a fetal PCA as the PCOM supioer/lateral to CN3, instead of superior/medial as in normal anatomy.
Diffuse astrocytomas
- Intro:
- 20% of all astrocytomas
- 20-40 year old
- Cerebral hemispheres
- IDH1 mutation present in the majority of adult and adolescent D.As
- Rad features
- Calcification in 20%
- Hx and extensive oedema are rare
- Mild enhancement
- Terminology
- The term diffuse astrocytoma should not be used for specific, non-infiltrative tumours of astrocyte-lineage such as pleomorphic xanthoastrocytoma, subependymal giant cell astrocytoma and pilocytic astrocytoma, as these have different prognoses, treatment and imaging features.
- Diffuse astrocytomas are divided into two molecular groups according to IDH status:
- IDH mutant
- IDH wild-type
- If IDH status is unavailable, they are known as
- diffuse astrocytoma NOS (not otherwise specified).
- Importantly, if IDH is shown to be mutated, then 1p19q status must be determined and shown to be not co-deleted (otherwise, even with astrocytic histology, an IDH mutated, 1p19q co-deleted tumour is now classified as an oligodendroglioma).
- It is also worth noting that is it likely that the entity diffuse astrocytoma IDH wild-type will eventually vanish, as it is felt that most of these tumours harbour a variety of other distinctive genetic profiles and likely represent a collection of other tumours with astrocytic histological differentiation 13.
Tectal Glioma
- A subcategory of Pilocytic Astrocytomas
- A type of localized astrocytic tumour
- Focal tumor localized to the tectal plate
- A distinct subset of brain stem gliomas
- Have a good prognosis and are located deep.
- They are usually followed without Bx with serial imaging to document stability
- if the lesion extends beyond the rectum bus is still confined to the midbrain = PRETECTAL TUMOUR which caries a worse prognosis
- Pre-tectal tumours are difficult to differentiate from pineal region tumours.
- Clinical presentation
- Their expansion within the brainstem causes narrowing the aqueduct of Sylvius and causing obstructive hydrocephalus with presentation usually secondary to headache 3-4.
- Additional symptoms may include gaze palsies, due to compression of the medial longitudinal fasciculus leading to an upgaze palsy, diplopia or Parinaud syndrome, although these are uncommon 3-4.
Spinal Ependymoma
- Cap sign. T2 hypointense cap around tumour secondary to haemosidderin.
Causes of CNS infections
in normal and reduced immunity
- Normal immunity
- Coccidioidomycosis
- histoplasmosis (Case)
- Blastomycosis
- Reduced Immunity
- Norcadosis
- Aspergillosis
- Candidiasis
- Cryptococcosis
- Mucormycosis
- https://www.cureus.com/articles/18340-disseminated-central-nervous-system-histoplasmosis-a-case-report
Gliomatosis Cerebri
- Gliomatosis cerebri is a rare growth pattern of diffuse gliomas that involves at least three lobes by definition, have frequent bilateral growth and may extend to infratentorial structures.
- There often is an important discordance between clinical and radiological findings, as it may be clinically silent while it appears as a very extensive process radiologically.
- Importantly, whereas gliomatosis was previously considered a distinct entity since the 2016 update to the WHO classification of CNS tumours it is now merely thought of as a growth pattern.
- Pathology
- The tumour may be primary (de novo) or secondary, with the latter as a result from the spreading of a more focal glioma 5. Gliomatosis cerebri growth pattern is seen in all diffuse gliomas and can contain areas of WHO grade II or III tumours and rarely grade IV 6,7. It is most commonly encountered in anaplastic astrocytomas.
- Classification
- Gliomatosis cerebri can be divided into two types 7:
- type 1: no discrete mass
- usually IDH wild-type
- type 2: discrete mass with further diffuse CNS involvement
- IDH1 mutation more common in this subtype
- type 1: no discrete mass
- Gliomatosis cerebri can be divided into two types 7:
- Predominately causes expansion of WM but may also involve deep gray nuclei and cortex
- Usually non-enhancing
- Late in disease small foci of enhancement become visible
- Leptomeningeal Gliomatosis can mimic meningeal carcinomatosis or leptomeningeal spread of primary CNS tumours with marked enhancement.
what is this
who does it happen to?
-
Cryptococosus
- Cystic lesions
- Gelatinous pseudocysts
- secondary to spread into VR spaces in basal ganglia.
- Consider in HIV patients with communicating hydrocephalus.
- CNS cryptococcosis results from infection of the central nervous system with the yeast-like fungus Cryptococcus neoformans. It is the most common fungal infection and second most common opportunistic infection of the central nervous system.
- Epidemiology
- The disease tends to be predominant in immunocompromised individuals such as those with AIDS. In immunocompetent patients, there is usually history of close contact with birds.
- Pathology
- Central nervous system involvement with cryptococcosis typically results from haematogenous spread from the lungs (which is usually the primary site).
- In HIV/AIDS patients cryptococcal infection of the CNS usually occurs when the CD4+ count drops below 100 cells/µL.
- The disease can have either meningeal or parenchymal involvement with the former being the primary manifestation 6.
- With meningeal involvement, a grayish, mucinous exudate accumulates over the involved brain surface.
- There are three dominant CNS forms to the disease depending on which part of the brain is affected:
- meninges: meningitis
- parenchyma: cryptococcomas
- perivascular spaces: gelatinous pseudocysts
- Radiographic features
- The disease can have a variety of radiographic presentations and is influenced by the degree of immunocompromise and therapy. As a result, the literature describing features has evolved considerably in parallel to marked improvements in the management of HIV and the availability of HAART.
- As a general rule, in patients who are profoundly immunocompromised (and therefore earlier literature), cryptococcosis demonstrates little enhancement. Instead, in patients who are on more effective therapy enhancement is more frequently encountered.
- The range of appearances includes:
- hydrocephalus
- dilated perivascular spaces coalescing into gelatinous pseudocysts
- leptomeningeal and pachymeningeal enhancement
- cryptococcomas (or torulomas)
- miliary nodules
- choroid plexus (plexitis)
- The most common pattern, particularly in profoundly immunocompromised patients is spread along the perivascular spaces, most commonly involving the basal ganglia but also the white matter of the cerebral hemispheres, the brainstem and cerebellum 12.
what is this.
- Progressive Multifocal Leukencephalopthy
(PML)
- INTRO
- Demyelinating disease casued by reactiveation of JC virus (a polyomarvirus)
- The reactivated virus infects and destroys oligodendrocytes.
- Imaging features
- posterior centrum semiovale is the most common site
- Bilateral but assymetric
- Begins in Subcortical WM, spreads to deep WM.
- T2 Bright lesions (parietooccipital)
- Usually no enhancement
- The key distinguishing features from infections and tumors.
- Although there is an inflammatory variant and acute demyelinating lesions can show variable enhancement.
- May cross corpus callosum
- No mass effect.
- Commonly effects the subcortical u-fibres
Presentation: 30M Inappropriate behaviour and difficulty at work, resulting in job loss.
Frontotemporal demential
30 year old male
MRI demonstrates marked frontal and temporal atrophy, more marked on the right. There is also reduction in the caudate head size, again more pronounced on the right. Hippocampal volumes appear preserved.
Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org. From the case rID: 14321
intro
peak age
types 3 and their supply
imaging features
complications
associations
- Arteriovenous malformation
- Intro
- abnormal network of arteries and veins with no intervening capillary bed
- 98% AVMs are solitary
- Peak age
- 20-40 years
- Types
- parenchymal 80%
- ICA, VA supply, congential lesions
- Dural
- 10%
- ECA supply
- mostly acquired
- Mixed
- 10%
- parenchymal 80%
- Imaging features
- MRI study of choice
- ateriography is superior of characterisation and tx planning
- Serpiginous high and low signal with feeding /drfaining vessels
- best seen on MRI/MRA
- Replaces but des to displace brain tissue
- mass effect is uncommon
- unless complicated by hx and oedema
- oeema occurs if hx or venous thrombus with infarction
- 10% flow related aneurysm
- Adjacent parenchymal atrophy
- 2secondary to steal and ischameia
- 25% calcify
- Swi +ve if old Hx
Fig. 5.1 A 47-year-old female with seizure. (a-d) Four slices of a T2-weighted MRI demonstrate an AVM with a relatively compact nidus in the left parietal lobe. There is a markedly hypertrophied left MCA branch, which feeds the AVM (white arrow). The AVM has a large venous pouch with associated surrounding edema and thrombus. (e) Left ICA cerebral angiogram shows a tortuous course of the left cervical ICA. There are proximal flow-related aneurysms of the paraophthalmic ICA and MCA bifurcation (diagonal arrows). There are feeding arterial aneurysms of the distal left MCA. There is a fistulous component to the AVM (horizontal white arrow), which dives into large venous pouches and ectasias. The draining vein is markedly dilated and has a long course. The fistulous component, thrombosed venous pouch with edema, and long course of the draining vein are all risk factors for seizures in this AVM patient.
5.1.2 Description of Imaging Findings and Diagnosis
Diagnosis
Fistulous type arteriovenous malformation (AVM) in the left parietal lobe with multiple feeding arterial aneurysms, a markedly hypertrophied MCA branch suggesting a fistulous component, multiple intranidal aneurysms, large venous pouches, and a long draining vein.
5.1.3 Background
Brain AVMs are substantially rarer than intracranial aneurysms with an estimated prevalence of 20 per 100,000 people. These lesions are thought to form either in utero or early in life; however, there are a few reported cases of de novo AVMs developing in adult patients. AVMs can have a wide range of presentations including rupture, seizures, headache, cognitive decline, weakness, sensory changes, or bruit. The risk of rupture of a brain AVM is estimated to be 2–3% per year. A simple formula proposed for determining a patient’s lifetime risk of an AVM bleed is 105-(patient age in years).
There are a variety of characteristics that need to be considered when evaluating an AVM. Perhaps, the most well-known AVM grading scheme is the Spetzler-Martin Grade, which grades AVMs on a 1–5 scale based on size, eloquence, and venous drainage to determine the patient’s risk of neurological deficit after surgical resection (Table 5.1). This scale neither evaluates natural history nor does it determine risk factors or success rates of radiosurgical or embolization treatment and thus cannot be used to characterize the risk of hemorrhage or potential success and complication rates of treatments other than surgery. Through extensive study of the imaging characteristics of brain AVMs, we now have a better understanding of which angioarchitectural characteristics are important for understanding AVM natural history, pathophysiology, and treatment decisions. In this chapter, we focus on defining various angioarchitectural terms, which will be expounded on in later chapters. These terms are summarized in Table 5.1.
https://radiologykey.com/5-cerebral-arteriovenous-malformations-avms-and-dural-arteriovenous-fistulas-davfs/
TUBERCULOMA
- rare unless reduced immunity or from endemic areas (India). Usually solitary.
- Non-specific enhancing mass-like lesion.
- Cerebral hemispheres and BG
- Millary form:
- multiple tiny parenchyma lesions.
- Intracranial tuberculous granulomas, also known as CNS tuberculomas, are common in endemic areas and may occur either in isolation or along with tuberculous meningitis.
- Epidemiology
- The epidemiology of patients with tuberculomas is the same as that of other CNS manifestations of tuberculosis (TB) (see CNS tuberculosis).
- Pathology
- A tuberculoma is distinct from a tuberculous abscess in that it demonstrates evidence of granulomatous reaction and caseous necrosis histologically. In contrast, abscesses do not display a granulomatous reaction and their centres are filled with pus 5,6. Not all tuberculomas, however, have a solid granulomatous core and some may undergo liquefaction 4. Tuberculous organisms may not necessarily be identified in tuberculomas, whereas they are necessary to make the diagnosis of tuberculous abscess 6.
- Radiographic features
- CT
- On CT, tuberculomas may appear as a round or lobulated nodule with moderate to marked oedema. Either solid or ring enhancement is typical post-contrast. A central focus of calcification with a ring of peripheral enhancement (the “target sign”) is described but is not specific to tuberculosis 7. When calcification is present (the minority of cases) it tends to be larger than that calcification seen in neurocysticercosis.
- MRI
- MRI is the modality of choice in assessing potential tuberculomas which have fairly solid caseous necrosis centrally on the background of granulomatous reaction. In some instances, however, liquefactive necrosis centrally can occur, and the imaging appearances are then essentially indistinguishable from a tuberculous abscess, which in turn is similar to pyogenic cerebral abscesses 4.
- T1 isointense to grey matter 1
- MRI is the modality of choice in assessing potential tuberculomas which have fairly solid caseous necrosis centrally on the background of granulomatous reaction. In some instances, however, liquefactive necrosis centrally can occur, and the imaging appearances are then essentially indistinguishable from a tuberculous abscess, which in turn is similar to pyogenic cerebral abscesses 4.
- CT
may have a central region of hyperintensity representing caseation
* T2
* isointense to grey matter
may have a central region of hypointensity representing gliosis and abundant monocyte infiltration 1
lesions are surrounded by vasogenic oedema
T1 C+ (Gd)
usually appears as ring-enhancement
may appear as a conglomerate enhancing mass
* DWI typically central low signal (i.e. no restricted diffusion) 3 but if liquid necrosis is present centrally may be high signal
* MR spectroscopy decrease in NAA/Cr slight decrease in NAA/Cho
lipid-lactate peaks are usually elevated (86%) 2
* Differential diagnosis
The differential of tuberculomas is primarily the differential of ring-enhancing lesions, and includes:
* other infection
* neurocysticercosis
* cerebral toxoplasmosis
* CNS cryptococcosis
* bacterial cerebral abscesses
* neurosarcoidosis
* cerebral metastases
* CNS lymphoma
* **Central isointensity or hypointensity compared to grey matter seen centrally on T2 is helpful, as it is not seen in most other causes 1.**
signs and symptoms of Osler-webber rendu
what is the AIF re perfusion imaging
Definitions of Trollard and Labbe veins
- Anastomotic vein of Trolard
- connects the suprficial middle cerebral vein and the superior sagital sinus
- Anastomotic vein of Labbe
- connects the superficial middle cerebral vein and the transverse sinus.
Brain abscess imaging Features
- Diffusion imaging highly sensitive to detect abscess and empyema.
- Risk factors for haematogenous spread include:
- right to left shunt
- congenital heart disease
- pulmonary AVM and AVFs as seen in hereditary haemorrhagic telangiectasia (HHT)
- infective endocarditis
- intravenous drug use (IVDU)
- lung infection
- lung abscess
- bronchiectasis
- empyema
- pneumonia
- sinonasal infections
- dental abscess
- systemic sepsis
- right to left shunt
- location
- hematogenous seeding
- multiple lesions at G/W matter junction
- penetrating trauma or sinusitis
- lesions around the entry site
- ring or wall enhancement 90%
- Capsule in 7-14 days.
- Casule thinner on WM side bc of lower perfusion of wm than gm.
- bc of this, daughter cysts tend to occur on the medial side
- ventriculitis
- ependymal enhancement
- DWI increased.
- May cause ventricular septations.
- The capsule is T2 hypointense. The inner margin is often smooth. capsule formation may be delayed by steroid administration.
- ventriculitis bc of ventricular spread.
- increased CSF density bc of increased protein.
- Pathology
- Cerebral abscesses result from pathogens growing within the brain parenchyma. Initial parenchymal infection is known as cerebritis, which may progress into a cerebral abscess. Historically direct extension from sinus or scalp infections was the most common source. More recently haematological spread has become most common. Direct introduction by trauma or surgery accounts for only a small minority of cases.
- Cerebral infection is commonly divided into four stages with distinct imaging and histopathologic features:
- early cerebritis( a focal infection without a capsule or pus formation,can resolve or develop into frank abcess)
- late cerebritis
- early abscess/encapsulation - may occur 10 days after infection
- late abscess/encapsulation - may occur >14 days after infection
- Microbiology
- Streptococcus sp: 35-50%
- especially S. pneumoniae 4
- sterile: 25%
- mixed: variable, 10-90% of cases depending on source
- Staphylococcus aureus and epidermidis:
- following neurosurgery
- Gram-negative species more common in infants
- Listeria in pregnant women and older patients
- group B Streptococcus (GBS) and E. coli in neonates
- Streptococcus sp: 35-50%
- The immunocompromised patient is susceptible to a host of other organisms including:
- Toxoplasma gondii
- Nocardia asteroides
- Candida albicans
- Listeria monocytogenes
- Mycobacterium sp
- Aspergillus fumigatus
- GBM
- most common primary brain tumour
- 55% of astrocytomas
- >50 years
- Majority arise de novo from neural stem cells
- Secondary GBM arise from lower grade astrocytomas and frequently carry IDH mutations with a more favourable prognosis
- Hemispheres
- Tumor spread
- WM tracts
- across midline via commisures (like the CC)
- Subependymal spread/seeding of the ventricles
- CSF seeding of S.A space.
- Imaging features
- CT - low density heterogenous mass
- Strong contrast enhancement
- Haemorrage and necrosis common
- Calc uncommon
- +++ vasogenic oedema and mass effect
- Bihemispheric Spread = butterfly lesion
- HIgh grad gliomas located peripherally can have a broad dural base and dural tail, mimicking extra axial lesion.
- CSF seeding leptomeningeal drop metastasis.
metachromatic leukodystrophy
This sign is characterized by multiple dark spots or stripes (spared perivascular white matter) of normal white matter intensity scattered within the bright demyelinated periventricular white matter on T2W images (Figure 10). Tigroid appearance of the white mater has been found in some cases with Pelizaeus-Merzbacher disease and metachromatic leukodystrophy. However, it has been recently reported that it may be observed in cases with lissencephaly accompanied by cerebellar hypoplasia [11,12].
Metachromatic leukodystrophy (MLD) is the most common hereditary (autosomal recessive) leukodystrophy and is one of the lysosomal storage disorders. It has characteristic imaging features including peri-atrial and to a lesser extent frontal horns leukodystrophy as well as periventricular perivenular sparing results in “tigroid pattern” on fluid-sensitive MRI sequences.
Epidemiology
It has an estimated prevalence of ~1:100,000 and typically manifests between 12 to 18 months of age. The disease can sometimes be classified according to the time of onset:
late infantile: most common ~65% (range 50-80%)
juvenile (onset between 3-10 years)
adult (after age 16)
Cerebral cavernous venous malformation
- Case Discussion
- This MRI demonstrates widespread focal regions of susceptibility induced signal loss (best seen on susceptibility weighted imaging (SWI)) ranging in size from microscopic to a number of millimetres in diameter
- Remember that all T2* sensitive sequences result in a degree of blooming and thus grossly overestimate the actual size of the lesion).
- One of the lesions in the right temporal lobe demonstrates high T1 and T2 signal centrally and perhaps a small amount of peripheral oedema, best seen on FLAIR. This suggests a recent bleed.
- This patient is from a known pedigree of autosomal dominant multiple cavernoma syndrome.
- DDx
- neurocysticercosis and
- cerebral amyloid angiopathy.
- Against the diagnosis of neurocysticercosis is the variability in the size of the lesions, which by the time they calcify are typically more regular, measuring a few millimetres each.
- Furthermore there is no calcification in this case, although on the sequences provided that cannot be proven.
- Review of a CT (not shown) or phase images of the SWI (also not shown) would confirm this.
- Cerebral amyloid angiopathy can have similar appearances however against this diagnosis is that A) the lesions, in this case, are distributed randomly throughout all parts of the brain, not having a predilection for the peripheral subcortical white matter which microhaemorrhage of cerebral amyloid angiopathy, and B) there is no evidence of prior larger lobar haemorrhage or superficial siderosis, both of which would be expected in this degree of change.
- Cerebral cavernous venous malformation
- Cerebral cavernous venous malformations, also commonly known as cavernous haemangiomas or cavernomas, are common cerebral vascular malformations, usually with characteristic appearances on MRI. It is the third most common cerebral vascular malformation after developmental venous anomaly and capillary telangeictasia.
- Cavernous malformations are found throughout the body. This article focuses on cerebral cavernous venous malformations. For a general discussion and links to cavernomas in other locations, please refer to the general article on cavernous venous malformation.
- Terminology
- Many alternative terms have been used over the years including cavernous haemangioma, cerebral cavernous malformation or simply cavernoma. As these lesions are not neoplastic, it has been argued that the terms ‘haemangioma’ and ‘cavernoma’ should be avoided. Additionally, it is important to note that according to newer nomenclature (ISSVA classification of vascular anomalies) these lesions are now officially termed slow flow venous malformations.
- Having said all that, it is probably helpful in reports to include the word ‘cavernous’ as this term is ubiquitous in the literature and most familiar to many clinicians.
- For clarity and brevity, the term cavernous malformation is used for the remainder of this article.
- Epidemiology
- Most patients who present symptomatically do so at 40-60 years of age. Most patients have single lesions. Multiple lesions may be familial and screening of family members may be indicated (see familial multiple cavernous malformation syndrome). Additionally, cavernous malformations, along with capillary telangiectasias, are commonly seen following cerebral radiotherapy 3.
- Clinical presentation
- The majority of lesions remain asymptomatic throughout life and are found incidentally. Presentation due to haemorrhage may cause a headache, seizure or focal neurological deficit. The risk of haemorrhage is 1% per year for familial cases and somewhat less for sporadic lesions.
- Pathology
- Histologically cavernous malformations are composed of a “mulberry-like” cluster of hyalinized dilated thin-walled capillaries, with surrounding haemosiderin 3. These vessels are thrombosed to varying degrees. Unlike AVMs, there is no normal brain between the interstices of these lesions.
- On occasion, they are intimately associated with a developmental venous anomaly (DVA), in which case they are known as a mixed vascular malformation.
- Radiographic features
- Cerebral cavernous malformations tend to be supratentorial (~80% cases) but can be found anywhere including the brainstem. They are usually solitary, although up to one-third of patients with sporadic lesions have more than one 2.
- CT
- Unless large, these lesions are difficult to see on CT. They do not enhance. If large they appear as a region of hyperdensity resembling blood products and speckles of calcification. If there has been a recent bleed then the lesion is more conspicuous and may be surrounded by a mantle of oedema.
- MRI
- MRI is the modality of choice, demonstrating a characteristic “popcorn” or “berry” appearance with a rim of signal loss due to haemosiderin.
- T1: varied signal depending on the age of the blood products, small fluid-fluid levels may be evident
- T2
- hypointense rim
- varied signal internally depending on the age of blood products
- if a recent bleed has occurred, surrounding oedema may be present
- GRE T2*/SWI
- prominent blooming
- useful for detecting smaller lesions otherwise missed by conventional spin echo sequences, especially in patients with familial or multiple cavernous malformations
- T1 C+ (Gd): generally no enhancement, although possible 7
- Cavernous malformations can be grouped into four types based on MRI appearances using the Zabramski classification 11.
- Angiography (DSA)
- Cavernous malformations are angiographically occult and do not demonstrate arteriovenous shunting.
- Treatment and prognosis
- Many cavernous malformations are asymptomatic and can be treated conservatively. Symptoms can relate to mass effect, epileptic activity or repeated haemorrhage. Symptomatic lesions should, when possible, be resected and complete resection is curative 9.
- Differential diagnosis
- The differential, when cavernous malformations are numerous, is that of other causes of cerebral microhaemorrhages, including 2:
- cerebral amyloid angiopathy: usually numerous small foci
- chronic hypertensive encephalopathy: more common in the basal ganglia
- diffuse axonal injury (DAI)
- cerebral vasculitis
- radiation-induced vasculopathy
- haemorrhagic metastases
- Parry-Romberg syndrome 2
- Larger lesions can mimic:
- haemorrhagic cerebral metastases
- haemorrhagic primary brain tumours (e.g. ependymoma, glioblastoma)
- Calcified lesions, such as old neurocysticercosis, or other infections (e.g. tuberculoma) should also be considered.
Ependymoma
- Slow growing tumour of ependymal lining cells usually location in or adjacent to ventricles within the parenchyma.
- fourth ventricle: 70% more common in children
- Lateral ventricle or periventricular parenchyma 30%.
- more common in adults
- Spinal Ependymomas are associated with NF1.
IMAGING FEATURES
- Growth patten depends on location
- supratentorial:
- tumours grow in the cerebral hemispheres (resemples an astrocytoma)
- remember to include ependymoma in the ddx of a supratentorial paranechyma mass lesion. Particularly a child.
- Infratentorial
- tumours grow inside fourth ventricle and extrude thoguht the foramen of LUSHCKA into the CPA and cisterna magana
- this appearance is characteristic of a PLASTIC EPENDYMOMA and often helps to differentiate an ependymoma from a medulloblastoma
- Hydrocephalus is virtually aways present when in the posterior fossa
- fine calcifations
- cystic areas
- haemorrage.
- supratentorial:
- DDX for sypratentorial Ependymoma
- embryonal tumour: often periphal and has more edema
- atypical teratoid/rhabdoid tumorL generally seen in infants and young children.
- GBM: may be indistinguishable but less likely to be in proxiity of ventricular surface
Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 5217
Vein of galen Varix
- Primary parenchyma AVM drains into VOG which secondarily enlarges
- Thalamic AVM with nidus is usually the primary avm
- Uncommon in neonates
- high risk of hx than GOV AVM
Abstract
A 28-year-old pregnant woman underwent an emergency caesarian section after 39 weeks of gestation because of decreased fetal movement and baseline fetal heart rate variability. The neonate was diagnosed with neonatal asphyxia and presented with right cardiac failure due to pulmonary hypertension. The neonate presented convulsion, and plane computed tomography (CT) showed dilation of the vein of Galen and sinuses on day 3. Magnetic resonance imaging and CT with contrast were performed after cardiac failure subsided, and there was no evidence of arteriovenous shunt and normalization of the vein of Galen. The patient was diagnosed with vein of Galen varix (VGV). In the previous literature, only 3 cases of VGV have been reported. VGV is considered to be caused by right cardiac failure without the presence of an arteriovenous shunt and requires treatment only for cardiac failure and its cause. Therefore, it is important to differentiate VGV from vein of Galen aneurysmal malformation.
https://www.karger.com/Article/Abstract/500768
Fahr Disease
RAD FEATURES
Stages
- INTRO
- HSV1
- oral
- kids and adults
- usually activation of latent virus in TRIGEMINAL GANGLION
- Change in mental status
- fulminant course
- LIMIBIC SYSTM
- Frequently bilateral but assymetric
- HSV2
- Genital
- neonatal TORCH infection
- acquired during parturition.
- maniefsts several weeks after birth
- diffuse/nonfocal encephalitis.
- HSV1
- CT MRI usually normal in early disease
- MRI -> 1st abnormality apparent in 2-3 days after onset.
- Distribution
- limbic system
- temporal lobe
- cingulate gyrus
- subfrontal region
- ACUTE stage
- emergency
- high mortality
- DWI restriction in affected areas
- Gyral oedema T1 hypo, T2 hyper
- no Enhancement
- Subacute stage
- increased oedema MARKED
- Bitlateral assymetric involvement
- gyral enhancement
- hemorrhage.
- Leigh Disease
ALZEIMERS
Dissecting aneurysm
- intor
- following a dissection an intramural haematoma may organise and result in a sac like outpouching
- causes
- trauma
- vasculopathy (SLE FMD)
- spont
- Location
- ICA > VA
- Imaging
- elongated contrast collections extending beyond the vessel lumen
- MRA - screening
- CTA dx and F/u
- Angio may be needed for imaging of vascular detail
Extensive subarachnoid blood is demonstrated within the suprasellar, ambient, and quadrigeminal plate cisterns and the sylvian fissures bilaterally. Large volume of blood also fills prepontine cistern and extends through foramen magnum. Intraventricular blood demonstrated within the lateral, third and fourth ventricles. Periventricular hypodensity likely related to chronic microvascular ischaemia.
A complex, multiple aneurysm arises from the right posterior inferior cerebellar artery (PICA) approximately 12mm beyond its origin, with both fusiform and saccular components. A high grade stenosis in the more proximal PICA supports a diagnosis of dissecting aneurysm.
Conclusion: Large volume subarachnoid haemorrhage (largest volume posterior fossa) with
intraventricular blood and hydrocephalus, with a large right PICA aneurysm.
A complex abnormality of the right PICA is shown - shortly after its origin there is an eccentric high-grade stenosis with small false aneurysm, and some 10 mm beyond this is a smaller 3 mm mixed fusiform and saccular aneurysm, just beyond this a larger 4.5 millimetre aneurysm at the bifurcation of PICA, incorporating both branches in its base. The left vertebral is patent and fills the basilar but is of smaller calibre. No other intracranial aneurysm, and no arteriovenous or dural arteriovenous fistula or malformation is shown.
Case Discussion
PICA dissection without involvement of the vertebral artery is rare but reported, and usually requires management with sacrifice of the vessel. Endovascular sacrifice is preferred over microsurgical exploration. In appropriate clinical circumstances, balloon occlusion testing of adequacy of collaterals can be considered.
https://radiopaedia.org/cases/posterior-inferior-cerebellar-artery-pica-dissecting-aneurysm-and-subarachnoid-haemorrhage?lang=gb
Cerebral amyloid angiopathy
Dr Rohit Sharma◉ and Assoc Prof Frank Gaillard◉◈ et al.
Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder caused by the accumulation of cerebral amyloid-β (Aβ) in the tunica media and adventitia of leptomeningeal and cortical vessels of the brain. The resultant vascular fragility tends to manifest in normotensive elderly patients as lobar intracerebral haemorrhage. It is, along with Alzheimer disease, a common cerebral amyloid deposition disease.
Epidemiology
Cerebral amyloid angiopathy can be divided into sporadic (spontaneous) and familial forms.
Sporadic CAA
Cerebral amyloid angiopathy is a frequent incidental finding, found on screening gradient-recalled echo imaging in up to 16% of asymptomatic elderly patients 4. Autopsy studies have found a prevalence of approximately 5-9% in patients between 60 and 69 years, and 43-58% in patients over the age of 90 4.
Autopsies of patients who have evidence of Alzheimer disease have found cerebral amyloid angiopathy in the vast majority of cases (90%). This rate is still high (20-40%) in non-demented elderly individuals 14.
Importantly it is usually not associated with systemic amyloidoses.
Familial CAA
Familial cerebral amyloid angiopathy describes a group of very rare disorders that are usually encountered as autosomal dominant conditions 14,21. Many of these disorders are only isolated to only a few families and they mainly differ from spontaneous CAA in an earlier age of onset, typically in middle to late middle age 14,21. Furthermore, they may also be part of multi-system or other central nervous system genetic disorders 14,21.
Examples of familial CAA include 21:
Aß peptide with precursor protein APP (chromosome 21):
CAA related to familial Alzheimer disease
CAA in Down syndrome
hereditary cerebral haemorrhage with amyloidosis (Dutch, Italian, Flemish, Iowa, Piedmont, Arctic types)
ACys peptide with precursor protein cystatin C (chromosome 20): hereditary cerebral haemorrhage with amyloidosis Icelandic type
ATTR peptide with precursor protein transthyretin (chromosome 18): meningovascular amyloidosis (see cerebral transthyretin-associated amyloidoses)
AGel peptide with precursor protein gelsolin (chromosome 9): familial amyloidosis - Finnish type
PrPSc peptide with precursor prion protein (chromosome 20): Gerstmann-Straussler-Scheinker disease
ABri peptide with precursor protein ABri precursor protein (chromosome 13): familial British dementia (see case 17)
ADan peptide with precursor protein ADan precursor protein (chromosome 13): familial Danish dementia
Clinical presentation
Manifestations of cortical vessel involvement:
lobar haemorrhages or cerebellar haemorrhages: present as stroke, often with headache, focal neurological symptoms, seizures, and decreased conscious state 19
cognitive impairment: occurs in three main patterns
gradual decline: a vascular dementia thought to be secondary to lobar cerebral microhaemorrhages, ischaemic leukoencephalopathy, microinfarcts, and lobar lacunes 7,15, and occurs independently to cognitive impairment of Alzheimer disease 25
step-wise decline: due to recurrent lobar haemorrhages 25
rapidly-progressive decline: may be present in inflammatory cerebral amyloid angiopathy 25, which is discussed separately
The primary manifestation of leptomeningeal vessel involvement is due to convexity subarachnoid haemorrhage, which can present with transient focal neurological symptoms (TFNS) or “amyloid spells” 25. These TFNS are classically described as recurrent, stereotyped, spreading paraesthesias lasting several minutes but there is a wide spectrum of presentations encompassing both positive (spreading paraesthesia or visual symptoms) and negative (paresis, aphasia or dysphagia) phenomenology 17,25. These symptoms are most prominent with the convexity subarachnoid haemorrhage is localised to the central sulcus 16, which is in close proximity to the primary motor and sensory cortices 25.
Other manifestations of CAA, which are discussed separately, include:
inflammatory cerebral amyloid angiopathy: an umbrella description for inflammatory reactions that present with rapidly-progressive cognitive decline, seizures, headache and stroke-like episodes (without haemorrhage) 1,11
cerebral amyloidoma: mass-like lesions that have a varied presentation depending on the location of the amyloidoma
Pathology
Cerebral amyloid angiopathy is characterised by the deposition of amyloid in the tunica media and/or tunica adventitia of small and medium-sized arteries of the cerebral cortex and leptomeninges 4,20. This is associated with fibrinoid degeneration with separation of the tunica media and tunica intima, and microaneurysm formation 1.
There are a number of different proteins that can lead to intravascular amyloid deposition, however, the most common, as is the case in sporadic CAA, is Aß which is a short 42 amino acid peptide cleaved from amyloid precursor protein (APP) which is encoded on chromosome 21 20.
Aß is an eosinophilic, insoluble protein, located in the extracellular space. It stains with Congo red yielding classic apple-green birefringence when viewed with polarised light 3,20. When staining with thioflavin T and illuminated with ultraviolet light, the Aß deposits emit bright green fluorescence 20.
Associations
Alzheimer disease
pathological cerebral amyloid angiopathy changes are seen in ~80% of those with Alzheimer disease (Aß-42) 5-13
~40% of those with cerebral amyloid angiopathy have Alzheimer dementia type symptoms
Down syndrome 25
chronic traumatic encephalopathy
spongiform encephalitis
other familial syndromes (as discussed above)
Radiographic features
Findings reflect the various manifestations of the disease:
haemorrhageintracerebral haemorrhageusually cortico-subcortical, in a so-called lobar location 22, but can also be seen in the cerebellum (especially in the cerebellar cortex or vermis) 24, may have finger-like projections 26
tend to spare the basal ganglia and pons (cf. hypertensive ‘deep’ intracerebral haemorrhage)
CT: initially hyperdense with hypodense perihaematomal oedema, often exerts positive mass-effect 25
MRI: appearance will vary according to age of bleed (see blood on MRI) 25
cerebral microhaemorrhagedefined as 2-10 millimetre, round or ovoid areas of haemorrhage, and tend to be corticosubcortical (grey-white matter junction) in distribution, but can also be in the cerebellum
tend to spare the basal ganglia and pons (cf. hypertensive microhaemorrhages) 4,14
CT: not appreciated 25
MRI: only seen on T2* sequences (GRE, echo-planar, SWI) as regions of low-signal blooming artefact 12,25, not seen on conventional T1 and T2/FLAIR sequences 4
convexity subarachnoid haemorrhagehaemorrhage that is localised to one or more adjacent cortical sulci at the convexity of the brain
tend to spare the basal cisterns, the Sylvian fissure, the interhemispheric fissure or the ventricles (cf. aneurysmal subarachnoid haemorrhage or perimesencephalic subarachnoid haemorrhage) 25
CT: hyperdensity localised to one or more adjacent sulci, can be subtle 25
MRI: appearance will vary according to the age of the bleed (see blood on MRI), but is best acutely seen on T2 FLAIR as a hyperintensity 18,25
cortical superficial siderosisa chronic sequela of convexity subarachnoid haemorrhage, including of haemorrhage that is asymptomatic 25
not present infratentorially (cf. superficial siderosis of the CNS) 25
CT: not appreciated 25
MRI: curvilinear regions of signal drop-out localised to one or more sulci best seen on T2* sequences (GRE, echo-planar, SWI) 9,25
ischaemiaischaemic leukoencephalopathy
chronic lesions, indistinguishable from leukoaraiosis due to other aetiologies, but tends to have a periventricular and posterior predominance 25
CT: diffuse hypodensity of the white matter 25
MR: T2 hyperintensity of the white matter without involvement of subcortical U-fibres (cf. cerebral amyloid angiopathy related inflammation) 7,25
microinfarcts and lobar lacunes
acute cortico-subcortical lesions; lobar lacunes are 3-15 millimetres in size while microinfarcts are smaller 25
CT: not appreciated 25
MRI: same signal changes as in acute ischaemic stroke, most pronounced on DWI 25
othersdilated perivascular spaces of the centrum semiovaledilation of normal perivascular spaces in the centrum semiovale 25
tend to spare the basal ganglia and pons (cf. hypertensive dilated perivascular spaces) 25
CT: not appreciated 25
MRI: best appreciated on T2 images as CSF-signal structures with a varied appearance depending on the orientation of their draining vessel 25
cortical atrophy
CT: not appreciated 25
MRI: not readily appreciated on conventional sequences, requires cortical surface reconstructions 25
Radiographic features of inflammatory cerebral amyloid angiopathy and cerebral amyloidoma are discussed separately.
Diagnostic criteria
The Boston criteria 7 and newer Modified Boston criteria 9 are a combination of clinical, radiographic and pathological criteria which are used to assess the probability of cerebral amyloid angiopathy. These criteria require patients to have either biopsy specimens and/or brain MRI data available 7,9. Additionally, the Edinburgh criteria for lobar intracerebral haemorrhage associated with cerebral amyloid angiopathy can be utilised, especially for patients with a lobar intracerebral haemorrhage without an MRI 26.
Treatment and prognosis
There is currently no disease-modifying treatment available 27. Additionally, there are no guidelines regarding use of antiplatelet, anticoagulant, or thrombolytic drugs in patients with CAA, all medications which have been shown to increase the risk of disabling haemorrhage in this patient group 27.
Differential diagnosis
Radiological differential diagnosis, particularly of cerebral microhaemorrhages, includes:
hypertensive microangiopathy
haemorrhages, including microhaemorrhages, are typically located in basal ganglia, pons and cerebellum
not associated with subarachnoid haemorrhage or superficial siderosis
multiple cavernoma syndrome
lesions have a random distribution
random size, although Zabramski classification type IV cavernous malformations are indistinguishable from cerebral microhaemorrhages related to CAA
often characteristic cavernous malformations can be identified
haemorrhagic metastases (e.g. melanoma)
lesions have a variable size and can often be larger than microhaemorrhages
enhancing
diffuse axonal injury
lesions are typically located at the grey-white matter junction, in the corpus callosum and in more severe cases, in the brainstem
neurocysticercosis
nodular calcified stage visible on CT or phase-filtered SWI
random distribution
fat embolism syndrome
‘starfield’ pattern of distribution
lesions also show restricted diffusion on DWI and are likely visible on other sequences
radiation-induced vasculopathy
microhaemorrhages have a very similar appearance (similar pathophysiology)
distribution related to the treatment field
Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 4717
Developmental venous anomaly
Dr Rohit Sharma◉ and Associate Professor Donna D’Souza◉ et al.
Developmental venous anomaly (DVA), also known as cerebral venous angioma, is a congenital malformation of veins which drain normal brain. They were thought to be rare before cross-sectional imaging but are now recognised as being the most common cerebral vascular malformation, accounting for ~55% of all such lesions.
A DVA is characterised by the caput medusae sign of veins draining into a single larger collecting vein, which in turn drains into either a dural sinus or into a deep ependymal vein. The appearance has also been likened to a palm tree.
Epidemiology
DVAs are very common as incidental finding, with an estimated prevalence of 2.5-9% on contrast-enhanced MRI scans 13.
Clinical presentation
Developmental venous anomalies are usually incidental findings. However, patients can present with intracranial haemorrhage (1-5%). An association has also been described with ischaemic stroke and epilepsy 8.
Pathology
The aetiology of developmental venous anomalies remains uncertain but may relate to arrested development of venous structures 2,3. Histologically they consist of a number of abnormally thickened veins with normal feeding arteries and capillaries 3.
Location and classification
The most common locations are:
frontoparietal region (36-64%) 1, usually draining towards the frontal horn of the lateral ventricle
cerebellar hemisphere (14-27%) draining towards the fourth ventricle
However, DVAs can be seen anywhere, draining either superficially or deep.
Associations
lesions are usually solitary (75%) 2, except in blue rubber bleb naevus syndrome
~20% (range 8-33%) of cases 2 are associated with cavernous malformations and are referred to as mixed vascular malformations (MVM)
venous malformations of the head and neck 2
cortical dysplasia (uncommon) 7
Radiographic features
Developmental venous anomalies are seen on both CT and MRI as a leash of vessels draining towards a central vein.
CT
If large, the draining vein may be seen on non-contrast CT and is confirmed with contrast administration as a linear or curvilinear enhancing structure.
Dystrophic calcifications may be seen associated in up to 9.6% of the cases 9. This can be particularly prominent in the basal ganglia and thalami resulting in unilateral calcification 10,11.
Angiography (DSA)
Angiographically the caput medusae appearance (collection of dilated medullary veins converge in an enlarged transcortical or subependymal collector vein) is pathognomonic and seen only in the venous phase. Arterial phase appears normal although late capillary blush may be present. No shunting is present.
MRI
Developmental venous anomalies are often visible on most sequences but can be subtle and are most easily seen on postcontrast T1 sequences and susceptibility weighted imaging (SWI). If there is an associated cavernous haemangioma, then susceptibility weighted sequences will be most sensitive to this component.
Additionally, in ~10% of cases, high T2 signal will be seen in the surrounding white matter; this may be due to gliosis, oedema or leukoaraiosis 12.
SWI is the preferred sequence in venous anomalies and proved to have better detectability of venous structures than conventional T2*-weighted imaging. Signals on SWI are not compromised by low-velocity venous flow. Therefore, SWI has successfully demonstrated low-flow vascular formations such as DVA. The signal intensity of veins will be low on SWI images but will vary on phase imaging depending on the vendor. It will, however, be the same as other veins and the opposite of calcification.
Treatment and prognosis
If isolated developmental venous anomalies require no treatment. If part of a mixed vascular malformation then treatment will be predicated on the other component. Informing the surgeon of the presence of a DVA is, however, essential as cautery of the collecting vein can lead to venous infarction of the brain parenchyma it drains.
When isolated, developmental venous anomalies have a very low complication rate (0.15% per annum) mainly from spontaneous thrombosis of the collecting vein leading to venous infarction and haemorrhage.
A more recent study has demonstrated that in exceedingly rare cases, the DVA can become symptomatic by various vascular complications. The authors suggested identification of the underlying pathomechanism by MR and DSA for proper management. The importance of the preserved integrity of the DVA itself still holds true 6.
Differential diagnosis
Generally, the appearances will be typical and no differential should be offered. In some instances, imaging appearances may be atypical or be confounded by concurrent pathology (e.g. haemorrhage). In such cases it is worth considering:
arteriovenous malformation
dural sinus thrombosis or dural arteriovenous fistula with collateral transparenchymal drainage
Sturge-Weber syndrome with leptomeningeal angiomatosis
demyelination may also have enlarged medullary veins
Practical points
think of an associated cavernoma when a developmental venous anomaly is found in the context of an intraparenchymal haemorrhage investigation, as isolated DVAs rarely bleed
developmental venous anomalies can be subtle on many MRI sequences; T1 C+ and SWI are most sensitive
- Imaging findings of TB Meningitis
- Tb meningitis is the most xommon CNS manifestation of TB followed by intraparenchymal Tuberculoma.
- Spread is usually hematogenous from pulmonary TB
- Basilar meningeal involvement by chronic granulomatous process leads to CN palsies.
- Basilar meningitis
- indistinguishable from fungal, lymphoma, sarcoid
- intense contrast enhancement of basilar meninges (CT/MRI)
- pituitary and para sellar involvement or hypothalamus involvement
- T2 hypointense meninges
- Calcifications occur late.
- Tuberculous meningitis is the most common presentation of intracranial tuberculosis, and usually refers to infection of the leptomeninges. Uncommonly tuberculosis can be limited to the pachymeninges (dura mater), it is called tuberculous pachymeningitis and is discussed separately.
- The remainder of this article pertains to leptomeningeal tuberculosis, which involves the arachnoid mater and pia mater.
- Epidemiology
- Tuberculous meningitis, although seen in all age groups, has a peak incidence in childhood (particularly 0-4 years of age) in high prevalence areas. In low prevalence areas, it is more frequently encountered in adolescents and adults.
- Important risk factors include:
- HIV/AIDS
- immunosuppression
- diabetes mellitus
- alcoholism
- caused by an abnormality in the copper transport protein, CERULOPLASMIN.
- AR inherritance
- MRI appearance of the cns may be normal
- T2hyperintense putamen and thalami
- CT: low density BG
- Hepatic cirrhosis
- Giant panda face sign.
Perimesencephalic subarachnoid haemorrhage
Dr Mostafa El-Feky◉ and Dr Laughlin Dawes et al.
Perimesencephalic subarachnoid haemorrhage (PMSAH) is a distinct pattern of subarachnoid haemorrhage (SAH), which is centred on the basal cisterns around the midbrain.
Epidemiology
Perimesencephalic subarachnoid haemorrhage is rare with an incidence of 0.5 in 100 000 in adults 4. PMSAH represents 5-10% of all subarachnoid haemorrhages and ~33% of all non-aneurysmal SAH 3,4.
Clinical presentation
As per subarachnoid haemorrhage.
Pathology
Aetiology
95% of cases of perimesencephalic subarachnoid haemorrhage have a normal cerebral angiogram and the source of bleeding is not identified; the cause is thought to be a venous bleed. This is referred to as non-aneurysmal perimesencephalic SAH.
The other 5% of cases are due to a vertebrobasilar aneurysm and the prognosis is worse 1,2. Rare causes include arteriovenous malformation, dural arteriovenous fistula, trauma and vascular tumours 4.
Radiographic features
CT
Perimesencephalic subarachnoid haemorrhage has been defined as subarachnoid haemorrhage, which on CT within three days of symptom onset 4:
is centred anteriorly to the pons and midbrain
may extend into the basal and suprasellar cisterns and into the proximal/basal Sylvian fissure and interhemispheric fissure
may settle as sediment in the occipital horns of the lateral ventricles but there is no overt intraventricular haemorrhage
Specifically, there are criteria for non-aneurysmal perimesencephalic SAH, which if fulfilled, in the presence of a negative CTA negates the need for DSA 5:
SAH in perimesencephalic cisterns anterior to midbrain
if SAH extension into the anterior interhemispheric fissure, not extending into all of the fissure
if SAH extension into the medial Sylvian fissures, not extending into the lateral fissure
if layering interventricular extension, no frank intraventricular haemorrhage
no intraparenchymal haemorrhage
Treatment and prognosis
CTA is recommended for perimesencephalic subarachnoid haemorrhage to investigate for possible aneurysmal cause. Overall, PMSAH has an excellent prognosis with better outcomes compared to aneurysmal SAH 1,2,4.
- AKA
- borreliosis
- WHAT
- deer tick vector
- Multisystemic inflam disease caused by a SPIROCHETE (Borrelia burgdorferi)
- single or multiple parenchymal abnormalities a/w meningeal and cranial nerve enhancement.
- MIMICs
- MS
- ADEM
- Lesions may or may not enhance.
- Lyme disease, also known as borreliosis, is a condition caused by the bacteria Borrelia burgdorferi, with infection being via the ixodid tick.
Terminology
- Controversy around Lyme disease centres on chronic infection with some authors doubting its existence 3. There are some terms that help differentiate these patients with non-specific symptoms of fatigue, myalgia, and arthralgia, from those with acute infection 3:
- post-Lyme disease symptoms: symptoms for <6 months
- post-Lyme disease syndrome: disabling symptoms lasting for >6 months
- Epidemiology
- Lyme disease is endemic in some areas of North America and Europe.
- Clinical presentation
- Three disease stages have been proposed manifesting after the tick bite 2:
- stage 1: flu-like illness and enlarging skin lesion (erythema migrans) (2-30 days)
- stage 2: cardiac and neurological symptoms (1-4 months)
- stage 3: arthritis and neurological symptoms (many years)
- Lyme disease has nonspecific symptoms with multisystemic involvement 1,2:
- Three disease stages have been proposed manifesting after the tick bite 2:
- Pathology
- Lyme disease caused by the bacteria Borrelia burgdorferi and is transmitted by the bite of the ticks Ixodes scapularis and Ixodes pacificus.
- Disease manifestations can be multisystem and nonspecific includes 1,2,4,5:
cutaneous: erythema migrans - CNS: peripheral neuropathy, radiculoneuropathy, myelopathy, encephalitis, meningitis, facial nerve palsy
- cardiac: myopericarditis, cardiac arrhythmia
- musculoskeletal: Lyme arthritis
- Radiographic features
- Intracranial MR imaging findings in patients with Lyme disease are rare 2. Where present, findings include:
- foci of periventricular / subcortical T2 hyperintensity
- nerve root enhancement
- meningeal enhancement
- Intracranial MR imaging findings in patients with Lyme disease are rare 2. Where present, findings include:
Radiotherapy induced microhaemorrhages
A previously biopsied lesion at the posterior aspect of the left cingulate gyrus. Minor local mass effect only. Diffuse punctate foci of susceptibility are consistent with post treatment change.
Case Discussion
This patient has a left cingulate gyrus anaplastic astrocytoma diagnosed 12 years ago treated with radiotherapy. The tumour has been been gradually growing over that time. Prominent changes of radiotherapy are noted conforming to the radiation field with a sharp demarcation.
Radiation induced microhaemorrhages are one of the most common complications of cranial radiotherapy and give you an insight into the part of the brain irradiated.
Choroid Plexus Pailoma/Carcinoma
radanatomy #radiology #RANZCRpart2exam #choroidplexuspapiloma
- Indistinguishable on radiology. Both may metastasize
- INTRO
- rare tumors that arise from the epithelium of choroid plexus
- Age: < 5 years
- They commonly present as a solid vascular tumour with a vivid frond-like enhancement pattern. In a quarter of cases, speckled calcifications are present.
- TYpes
- Choroid plexus Papilloma
- 90%
- Choroid plexus carcinoma
- 10%
- Choroid plexus Papilloma
- Typical locations
- Kids: trigone/atrium
- Adults: 4th ventricle/CPA
- METS
- drop Mets to spinal cord
- IMAGING Features
- intraventricular mass
- intense enhancement
- ventricular dilatation secondary to CSF overproduction or obstruction
- Calcifications 25%
- Supratentorial tumors supplied by choroid arteries
- Complications
- hydrocephalus and
- Drop mets
- Choroid Plexus Papiloma
.
CLUES: - intraventricular Mass
- Hydrocephalus
- Young child
- Fine speckled calcifications
- Can have small flow voids
.
DON’T MISS - Drop mets
.
DDX - Atypical Choroid plexus papilloma
- Choroid plexus Carcinoma
- Choroid plexus met
- if in the posterior fossa ddx include:
- Medulloblastoma
- ATRT
- Ependymoma
.
DDx in Adults: - Central neurocytoma
- intraventricular meningioma
- Subependymoma
- Ependymoma
Dural/Pachymeningeal Mets DDX
And 4 pathological processes
1 x mimick
- INTRO
- Mets are a common cause of dural mass But less common than brain mets and meningiomas
- MIMICK
- ‘en Plaque’ meningioma
- Pathological processes
- direct spread from Skull lesion
- Haematogenous
- Lymphatic
- Retrograde seeding from vertebral venous Plexus
- DDX (most common to less common)
- breast
- Prostate
- Lung
- H/N
- Haem
- Neuroblastoma
- Gastric adenoca
- Colon ca
- GBM
WHAT:
WHO:
HOW DOES IT LOOK?:
three presentations/appearances on MRI
- WHAT
- yeast
- cryptococosis neoformans
- yeast
- WHO
- occurs in immunocomprisied hosts
- HIV/AIDS
- Contact with births
- occurs in immunocomprisied hosts
- PRESENTATION
- manifests as meningitis (more common) and intraparenchymal lesions
- Three main presentations
- 1: T2 hyperintense foci that suppress on FLAIR in Basal Ganglia and Midbrain
- Gelatinous pseudocysts
- “Soap Bubble appearance
- Focal masses with variable enhancement
* crtocococcomas
- Focal masses with variable enhancement
- Meningitis
- 1: T2 hyperintense foci that suppress on FLAIR in Basal Ganglia and Midbrain
