Neuro Flashcards
HELPFUL VIDEOS
STROKE
https://www.youtube.com/watch?v=rruRwWIthbw
ISCHAEMIC STROKE
https://www.youtube.com/watch?v=2IgFri0B85Q
GBM
https://www.youtube.com/watch?v=GiV_XyyvNz8
TBI
https://www.youtube.com/watch?v=hssdJu-81g4
MYASTHENIA GRAVIS
https://www.youtube.com/watch?v=bYGxGdu9MsQ
PROGRESSIVE NEUROCOGNITIVE DISEASE
https://www.youtube.com/watch?v=KdcjyHvaAuQ
ACQUIRED DEMYELINATING DISEASES
https://www.youtube.com/watch?v=0jdT0OBZq90
LEUKODYSTROPHIES
https://www.youtube.com/watch?v=7eO8kQOW7GY
CNS TUMOURS
https://www.youtube.com/watch?v=ykrBO6F39zU
HUNTINGTINS
https://www.youtube.com/watch?v=wJAerjsZyZE
MUSCULAR DYSTROPHY
https://www.youtube.com/watch?v=DGOmN6rnsNk
MENINGITIS
https://www.youtube.com/watch?v=gIHUJs2eTHA
MS
https://www.youtube.com/watch?v=yzH8ul5PSZ8
Learning Neuroradiology youtube channel
https://www.youtube.com/channel/UC6RICkCkDRjxar5rdsVJStA
Virchow Robbins spaces (dilated perivascular spaces)
Fluid filled spaces that accompany perforating vessels.
Normal variant, very common. Can be associated with mucopollysaccharoidosis, cryptococcal meningitis, age. Have interstitial fluid, not CSF
Cavum variants
CAVUM SEPTUM PELLCIDUM
100% preterm infants, 15% adults. Rarely cause hydro. Anterior to foramen of Munroe between frontal horns
CAVUM VERGAE
Posterior continuation of cavum septum pellucidum, posterior to foramen of Munroe between bodies of lat ventricles
CAVUM VELUM INTERPOSITUM
Extension of quadrigeminal plate cistern to foramen of Munro. Seen above 3rd ventricle and below fornices.
Carotid canal anatomy
Split into 2 components by jugular spine.
PARS NERVOSA
anteromedial. CN9 and its tympanic branch Jacobsens nerve
PARS VASCULARIS
jugular bulb, CN10 and branch Arnolds nerve, CN11
Cavernous sinus
Carotid artery and CN6 medially (hence lateral rectus palsy in cavernous sinus pathology)
CN 3, 4, V1 and V2 in lateral wall
IAC
7UP COKE DOWN on heavy T2 weighted
CN7 and superior vestibular nerve are superior
CN8 and inferior vestibular nerve are inferior
Skull foraminae contents
OVALE
CNV3, accessroy meningeal a
ROTUNDUM
CNV2 (remember R2V2)
SOF
CN3, CN4, CNV1, CN6
IOF
CNV2
SPINOSUM
middle meningeal a
JUGULAR FORAMEN
Nervosa CN 9
Vascularis CN10, CN11
HYPOGLOSSAL CANAL
CN12
OPTIC CANAL
CN1, opthalmic a
CAVERNOUS SINUS
CN3, CN4, CNV1, CNV2, CN6, carotid a
IAC
7up coke down and sup/inf vestibular nerves
MECKEL CAVE
Trigeminal ganglion
DORELLOS CANAL
CN6, inferior petrosal sinus
Branches of external carotid
“some admin love fucking over poor medical students:
Superior thyroid Ascending pharyngeal Lingual Facial Occipital Posterior aricular Maxillary Superficial temporal
Segments of carotid artery
“cummon please learn clinical carotid organising classification”
Cervical Petrous Lacerum Cavernous Clinoid Opthalmic/supraclinoid Communicating
Acute CN3 palsy
PCOM aneurysm.
Anerysm at basilar artery or junction with superior cerebellar/posterior cerebral arteries can also cause this.
Vascular variants round COW
FETAL ORIGIN PCA
30% gen pop. posterior communicating is larger than P1 so occipital lobe is fed by ICA
PERSISTENT TRIGEMINAL ARTERY
Fetal connection between cavernous ICA and basilar. Tau sign on sag MRI. Increased risk of aneurysm
Anastomotic superficial veins
VEIN OF TROLARD (TOP)
Connects superficial middle cerebral vein and superior sagittal sinus. Small.
VEIN OF LABBE (LOW)
Connects superficial middle cerebral vein and transverse sinus. Large
EXTRA - NOTE ANASTOMOTIC
BASAL VEIN OF ROSENTHAL
Deep vein that passes lateral to midbrain through ambient cistern and drains into vein of Galen. SImilar course to PCA.
VEIN OF GALEN
Formed by union of two internal cerebral veins
Superficial vs Deep cerebral veins
SUPERFICIAL Superior cerebral veins Superior vein of Trolard Inf vein of Labbe Supperficial middle cerebral veins
DEEP
Basal vein of Rosenthal
Vein of Galen
Inferior Petrosal sinus
Brain myelination appearance
Infant brain has opposite signal characteristics on MRI due to myelin changes
Immature myelin has higher water content so is brighter on T2 and darker on T1. DUring maturation, water decrease and fat increase and signal characteristics change.
T1 changes precede T2 (adult T1 pattern age 1, adult T2 pattern age 2.
Immature myelin high water, low fat, T1 dark, T2 bright (adult opposite)
Brain myelination pattern
brainstem, posteior limb internal capsule myelinated at birth
ORDER OF PROGRESSION inferior to superior posterior to anterior central to peripheral sensory fibres prior to motor fibres subcortical white matter last to myelinate
Sinus development
Develop in following order:
Maxillary - present at birth, see on CT 5month
Ethmoid - present at birth, see on CT 1year
Sphenoid - NOT present at birth, see on CT 4year
Frontal - NOT present at birth, see on CT 6year
Corpus callosum agenesis (failure to form)
Forms front to back therefore agenesis often at back (splenium)
Colpocephaly (asymmetric dilatation of occipital horns) often shown which can be pericallosal lipoma or corpus callosum agenesis of splenium
“slit ventricles” in agenesis as Probst bundles are densely packed white matter tracts which would have otherwise crossed CC but now run parallel to interhemispheric fissure making ventricles look widely spaced and slit like. Steer Horn appearance on coronal.
Intracranial lipoma
Most classic association with CC agenesis. 50% at interhemispheric fissure, 2nd most common quadrigeminal cistern. Non fat sat T1 most helpful sequence. Asymptomatic.
Anencephaly (failure to form)
Neural tube defect at top of head. Top of head is absent above the eyes.
Reduced/absent cerebrum and cerebellum. Hindbrain will be present. Not compatible with life
Frog Eye appearance on conronal due to abent cranial bone/brain wit bulging orbits.
Antenatal USS with polyhydramnios (cant swallow). AFP elevated.
Iniencephaly (failure to form)
Neural tube defect at level of cervical spine. Deficient occipital bone with defect in cervical region (inion = back of head)
Extreme retroflexion of head. Enlarged foramen magnum. Usually not compatible with life.
Star Gazing Fetus. Makes face turn upward with hyperextend cervical spine, short neck. AFP elevated
Encephalocoele (aka meningoencephalocoele) failure to form
Brain and meninges herniate through a defect in cranium. Most midline and occipital. Most classic with Chiari 3
Cerebellar Vermis abnormality (failure to form)
RHOMBOENCEPHALOSYNAPSIS
Vermis absent. Trasnversely oriented single lobed cerebellum. Absence of vermis means abnormal fusion of cerebellum. SMall 4th ventricle. Absent primary fissure. Associated with holoprosencephaly.
JOUBERT SYNDROME
Absent or small vermis. Molar Tooth appearance of superior cerebellar peduncles. Small cerebellum, absence of pyramidal decussation. Large 4th ventricle. Associated with retinal dysplasia, MCDK, liver fibrosis (COACH syndrome)
Dandy Walker (failure to form)
3 KEY FINDINGS
Hypoplasia of vermis (usually inferior part).
Hypoplastic vermis is elevated and rotated.
Dilated cystic 4th ventricle.
cerebellar vehemispheres will be displaced forward and lateral but overall volume and morphology are preserved.
Torcula-lambdoid inversion. Normally the lambdoid is above torcula, in DW, torcula is elevated above lambdoid
Often identified on obstetric USS
Presents with symptoms of raised ICP
Most common macrocephaly in 1st month
Associated with hydrocephalus and can have CC agenesis, encephalocoeles, heterotopia, polymicrogyria
variants not quite meeting DW include mega cisterna magna and blake pouch (cystic protrusion through foramen of magendie into retrocerebellar region)
Holoprosencephaly (failure to cleave)
Occurs along spectrum. Failure of midline cleaving. Cleavage occurs back to front (opposite of CC)
LOBAR
Mild fusion frontal horns, incomplete septum. Normal thalamus. Absent septum pellucidum +/- CC.
SEMILOBAR
Fused frontal lobes >50%. Body of lateral ventricles are single chamber. Absent septum pellucidum, CC, anterior interhemispheric fissure, falx cerebri anteriorly. Cleft lip/palate. Thalamus fused
ALOBAR
Monoventricle with rim of cortical mantle. Cerebral hemisphere fused with single midline ventricle. Thalamus fused. Absent septum pellucidum, CC, interhemispheric fissure, falx cerebri. Cyclops face. Still born.
Buzz words for HPE. Monstor cyclops eye, cleft lip/palate, pyriform aperture stenosis, solitary median maxillary incisor (mega incisor)
Two random conditions
ARHINCEPHALY
Minor HPE expression. Midline olfactory bulbs/tracts absent. Cant smell. Can be part of Kallmann Syndrome (also has hypogonadismand mental retardation)
MECKELL-GRUBER
Occipital encephalocoele, multiple renal cysts and polydactyly. Strongly associated with HPE.
Septo-optic Dysplasia (de Morsier syndrome)
Absent septum pellucidum.
Hypoplastic optic structures such as optic chiasm and optic nerves.
Associated with scizencephaly. Also can have azygod anterior cerebral artery which is common trunk of anterior cerebral arteries.
Neuronal cortex formation
Brain forms from inside out. Neurons are all in slurry surrounding fetal ventricles (germinal matrix) then climb to cortex.
PROLIFERATION
Neuronal-glial cells in periventricular pit where they divide into additional cells symmetrically. Stay until they get signal to undergo apoptosis. Number of neurons in cortex determined by frequency and number of divisions by stem cells. Disturbance here will result in too few/too many/improper neurons
MIGRATION
Cells make climb to cortex guided by structural cells, chemical signals. Climb in 6 waves with preplate then cortical plate.Therefore, organised in inside-out pattern. Disturbance here results in undermigration/overmigration/ectopic neurons
ORGANIZATION
Cortical folding required once at destintion. Depends heavily on 1st 2 steps. Differential speed of cortex expansion is key to mechanism for brain folding. Need right number of cells migrating in right order. Continued differentation into structural cell types which organize into horizontal/vertical columns creating underlying cytoarchitecture for sturcture and function. DIsturbance here results in absence or excessive number of folds.
Unilateral dilated ventricle (failure to proliferate)
Failure to proliferate
HEMIMEGALENCEPHALY
Big side with big ventricle. Hamartomatous overgrowthof all or part of a cerebral hemisphere, secondary to differentiation/migration failure
RASMUSSENS ENCEPHALITIS
Small side with big ventricle. Shrunken half is atrophic resulting in ex-vacuo dilatation.
Lissencephaly Classic type 1
Undermigration.
Smooth surface, thick cortex. Colpocephaly figure 8 shape.
Failure to migrate both in amount and in order with a reverse outside in pattern. Large numbers neurons dont reach cortical plate depositing between ventricular and pial surfaces. 4 layers instead of 6. Cortical folding doesnt take place. Shallow sylvian fissures. Association with CMV
Double cortex band heterotopia
Undermigration.
Mildest form of classic Lissencephaly.
disorganized migration results in second layer of cortical neurons deep to superficial cortex. creates double cortex appearance. associated with seizure disorders.
gyral pattern is normal with subcortical band of heterotopic gray matter.
Cobblestone Lissencephaly type 2
Overmigration.
Overmigration of neurons to cortex reults in an additional layer of cortex composed of gray matter nodules.
Nodules in varying shapes/sizes. Most commonly located adjacent to sylvian fissures.
Cobblestone cortex. associated with congenital muscular dystrophy and retinal detachment.
Periventricular nodular heterotopia
Failed migration.
Neurons in periventricular/subependymal region did not migrate resulting in gray matter deposition along ventricle borders.
Most common spot for gray matter heterotopia. associated with seizures.
Polymicrogyria (failure to organize)
During normal migration, layer 5 can get affected by toxins/infection etc and cause more superficial layers to overfold and fuse resulting in excessive folding seen in polymicrogyria
Fine undulating bumpy cortex. Variety of shapes and sizes. Most common adjacent to sylvian fissure.
Scizencephaly (failure to organize)
Vascular insult proposed. 30% with scizencephaly also have non CNS vascular stigmata.
Cleft connecting CSF spaces with ventricular system. Can be unilateral or bilateral.
CLOSED LIP 20%
Less common, less severe. Lip is closed without a CSF cleft. Gray matter running accross norml corona radiata. Sometimes see nodule of gray matter at ventricular surface.
OPEN LIP 80%
More common, more severe. CSF filled cleft ventricle to pial surface. Lined with gray matter.
Associations: absent septum pellucidum, focally thinned CC, optic nerve hypoplasia, epilepsy.
Developmental failure mimics
PORENCEPHALIC CYST.
Brain celft/hole from prior insult resulting in encephalomalacia. Can communicate with subarrachnoid space externally or ventricle internally. NOT lined with gray matter
HYDRANENCEPHALY
bilateral ICA occlusion results in massive destruction both cerebral hemispheres. Only midbrain, cerebellum and falx remain. Herpes most classic but in utero infection with toxo or CMV also described.
Cephalocoeles
Herniation of contents through a defect in the skull
MENINGOCOELE
CSF and meninges, no brain
MENINGOENCEPHALOCOELE aka ENCEPHALOCOELE
CSF, meninges and brain
CYSTOCOELE
CSF, brain, meninges and ventricle
MYELOCOELE
Spinal cord
Chiari Malformations
TYPE 1
Herniation of cerebellar tonsils more than 5mm. Association with syrinx. Congenital underdevelopment of posterior fossa leading to overcrowding and downward displacement. Can get occipital hadache worse with sneezing. Weakness, spasticity, loss of proprioception. Can be associated with Klippel Feil syndrome - congenital c spine fusion. Not associated with neural tube defect
TYPE 2
Less tonsillar herniation, more cerebellar vermian displacement. Classic features low lying torcula, tectal beaking, hydrocephalus, clival hypoplasia. Can have interdigitated cerebral gyri. Lumbar myelomeningocoele/SPina Bifida. NTD sucks cerebellum downward prior to development of cerebellar tonsils.
TYPE 3
Features of 2. Also have occipital encephalocoele containing cerebellum and/or brainstem, occipital lobe and sometimes 4th ventricle. Associated with syrinx, tethered cord, hydrocephalus, agenesis CC.
TYPE 4.
Severe cerebellar hypoplasia.. Has fallen out of favor.
Mesial temporal sclerosis
Hipocampal volume loss + gliosis/scar resulting in intractable seizures. Likely developmental. Most common cause of partial complex epilepsy.
Reduced hippocampal volume, increased T2 signal from scar, loss of normal morphology/interdigitations. Can also get atrophy ipsilateral fornix and mammillary body. COntralateral amygdala enlargement.
Monro-Kellie Hypothesis
Head is closed shell. 3 major components: brain, blood and CSF are in state of dynamic equilibrium. As volume of one goes up, another goes down.
Intracranial Hypotension
Leaking CSF decreases overall fixed volume. As a result volume of venous blood increases to compensate. Causes meningeal engorgement (enhancement) and distension of dural venous sinuses, prominence to intracranial vessels and engorgement of pituitary. Development of SDH and hygromas is classic look
Idiopathic intracranial hypertension (pseudotumour cerebri)
Overweight middle aged woman with headache is classic.
Making too much CSF or not absorbing properly. Ventricles become slit like, pituitary shrinks, venous sinuses compress. vertical tortuosity of optic nerves and flattening of posterior sclera.
Can get downward displacement of brainstem stretching 6th nerve resulting in 6th nerve paresis.
Hydrocephalus
COMMUNICATING
All ventricles are big. Obstructin between basal cisterns and arachnoid granulation. CSF can exit all ventricles.
causes blood/pus/cancer clogging villi SAH, meningitis, carcinomatosis
causes brain atrophy, NPH, CSF secreting tumour
NON-COMMUNICATING
upstream ventricles big, obstruction within ventricular system, CSF cannot exit all ventricles.
causes FoM colloid cyst, aqueductal stenosis or tectal glioma,posterior fossa tumour, cerebellar edema/bleed
Normal Pressure Hydrocephalus
Idiopathic
Wet, wacky, wobbly (urinary incontinence, confusion, ataxia). Elderly patients, ataxia comes first.
ventricular size out of proportion to atrophy. Frontal and temporal horns most affected. Upward bowing of CC. Transependymal flow in acute hydro.
SHYMA is similar but in middle age (syndrome of hydrocephalus in young and middle-aged adult)
Congenital hydrocephalus
Typically diagnosed prior to birth via USS
Aqueductal stenosis
Neural tube defect - usually Chiari 2
Arachnoid cysts
Dandy Walker
Aqueductal Stenosis
Most common cause of congenital obstrctive hydrocephalus
Classicaly from web ofr diaphragm a the aqueduct. Non-communicating with dilatation of lateral ventricles and 3rd ventricle with normal 4th ventricle. Can have macrocephaly with thinning of cortical mantle.
Treatment shunting or ventriculostomy. Sunset eyes or upward gaze paralysis.
Arachnoid cysts
Cysts in subarachnoid space. CSF density without solid component or restricted diffusion. Can block CSF pathway and have mass effect on brain.
CSF shunt malfunction
Normal is proximal shunt in frontal horn lateral ventricle by FoM, valve to control flow and distal tip usually in peritoneum but can be right atrium or pleural space.
UNDERSHUNTING
Most common cause is ingrowth of choroid pexus and particulate debris/blood products. Can also be from catheter migration. ALso distally can be from pseudocyst (loculated fluid at distal tip)
OVERSHUNTING
Slit like ventricles can mean too much shunting. Concern is for SDH or hygroma formation
INFECTION
Usually within 6 months of placement. Blood cultures negative, need to cultre shunt fluid. Debris within ventricles. Need DWI for ventriculitis. Ventricular loculations
HYDROTHORAX
Catheter can be deliberately in pleural space or migrate there. A little fluid is fine but if patient symptomatic may need revision.
ASCITES
Little fluid is fine but large amounts can cause herniae or hydrocoeles
Edema
CYTOTOXIC
Intracellular swelling secondary to malfunction of Na/K pump. Favours gray matter, loss of GW differentiation. Seen in stroke or trauma. BBB intact
VASOGENIC
Extracellular, secondary to disruption of the BBB. Edema tracking through white matter. Seen with tumour and infection. Response to steroids is classic of vasogenic edema
Types of herniation
SUBFALCINE
Same as midline shift, can get ACA compression
DESCENDING TRANSTENTORIAL (UNCAL) Uncus and hippocampus herniate through tentorial incisura. Perforatingbasilar artery branches get compressed resulting in DUrets haemorrhages in midline at pontomesencephalic junction. CN3 gets compressed between PCA and SCA causing pupil dilatation and ptosis
ASCENDING TRANSTENTORIAL
Posterior fossa mass causing vermis to herniate upwards through tentorial incisura. Can cause severe obstructive hydrocaphalus.
CEREBELLAR TONSIL HERNIATION
Severe herniation after downwards transtentorial herniation. Or Chiari
Central Pontine Myelinolysis
T2 bright pons which spares the periphery. Restricted diffusion lower pons. Can have extra-pontine presentation involvng basal ganglia, external capsule, amygdala and cerebellum.
Low sodium corrected too quickly. Can become encephalopathic with spastic quadriparesis. SLurred speech, sensitive gag reflex and labile emotional response.
Wernicke Encephalopathy
High T2/Flair signal in medial thalamas and periaqueductal gray matter, mamillary bodies andtectal plate. MR spect shows lactate, treatment is thiamine replacement.
Clinical triad of acute confusion, ataxia and opthalmoplegia. Thiamine (vitamin B1) deficiency is cause. Can progress to chronic memory loss and confabulation (Korsakoff psychosis)
Marchiafava-Bignami
High T2/Flair in CC representing acute demyelination. Progresses, beginning in body then genu then splenium. Sanwhich sign on sagittal describes pattern of preference for central fivers with relative sparing of dorsal and ventral fibers. Thinned CC and cystic cavities favoring genu and splenium
Associated with alcohol. Presents with confusion and alterd gait. Seizure and muscle rigidity
Random metabolic findings
ALCOHOLIC INJURY
Most common is brain atrophy, particularly cerebellum esp vermis
COPPER AND MANGANESE DEPOSITION
T1 bright basal ganglia. Non specific and related to liver disease. Can be seen without hepatic encephalopathy. Also seen in TPN, Wilsons.
METHANOL TOXICITY
Optic nerve atrophy, haemorrhagic putaminal and subcortical white matter necrosis.
Carbon Monoxide vs Methanol
Carbon Monoxide has CT hypodensity/T2 bright in globus pallidus (carbon causes globus warming)
Methanol T2 bright putaminal which may be haemorrhagic and thus CT hyperdense
Posterior Reversible Encephalopathy Syndrome (PRES)
Asymmetric cortical and subcortical white matter edema, usually in parietal and occipital regions. Does NOT restrict diffusion (rule out stroke).
Poorly understood but issue with autoregulation. History of acute HTN or chemotherapy.
Post chemotherapy
PRES
Chemo is classic cause but tends to have non classic look relative to HTN cause, sparing occipital lobes and targeting basal ganglia, brainstem and cerebellum
LEUKOENCEPHALOPATHY
Treatment induced. Classic look would be centered in periventricular white matter. Bilateral, symmetrical confluent T2/Flair bright changes. Disseminated necrotizinf variant has severe changes including ring enhancement in leukaemia patients undergoing radio/chemo
Post radiotherapy
T2 bright areas and atrophy corresponding to the radiation portal. Also see haemosiderin deposition and mineralizing microangiopathy (calcs in basal ganglia and subcortical white matter). Latent period so findings not seen for up to 2 months post radiotherapy.
Heroin Inhalation Leukoencephalopathy
‘chasing the dragon’
High T2/Flair in centrum semiovale symmetrically. High signal in posterior limb of internal capsule, deep cerebellar white matter which spares dentate nucleus.
Multiple Sclerosis
Perivascular pattern involving juxtacortical and periventricular regions with lesions having ovoid/fusiform morphology.
Lesions disseminated in space (periventricular, juxtacortical, infratentorial, spinal cord) with more than 1 in at least 2 of these locations. Lesions disseminated in time. T2 bright lesion that does enhance (active) and one that doesnt enhance (non active).
Targets women 20-40.
Multiple subtypes with relapsing/remitting most common 85%.
Separated by time and space is critical.
Multiple Sclerosis Trivia
T2/Flair oval and periventricular perpendicularly oriented lesions (Dawsons fingers)
Involvement of calloso-septal interface is 98% specific for MS
Posterior fossa more commonly invovled in children
Brain atrophy accelerated in MS
Solitary spinal cord involvement can occur but usually in addition to brain lesions
Cervical spine most commonly spinal portion effected 65%
SPinal cord lesions peripherally located
MR spectroscopy shows reduced NAA peaks within plaques
Acute demyelinating plaques should enhance and restrict diffusion.
Big plaque will have INCOMPLETE ring enhancement - tumefactive demyelination
Multiple Sclerosis variants
ACUTE DEMYELINATING ENCEPHALOMYELITIS (ADEM)
Presents in childhood or adolescents after viral illness. Multiple large T2 bright lesions enhancing in nodular or open ring pattern. does NOT involve calloso-septal interface
ACUTE HAEMORRHAGIC LEUKOENCEPHALITIS (HURST DISEASE)
Fulminant form of ADEM with massive brain swelling and death. Haemorrhage seen at autopsy
DEVICS (NEUROMYELITIS OPTICA)
Transverse myelitis and optic neuritis. Lesions in cord and optic nerve
MARBURG VARIANT
Childhood variant that is fulminant reading to rapid death. Febrile prodrome.
Subcortical Arteriosclerotic Encephalopathy (SAE)
Binswanger disease. Multi infarct dementia.
Favours white matter of centrum semiovale. Spares subcortical U fibres. Strong association with hypertension. Seen in older people, 55 and up.
Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL)
SAE in younger person with migraines. Classic might say 40yo with migraines then strokes then eventual dementia.
CADASIL is most common hereditary stroke disorder.
Severe white matter disease high T2/Flair involving multiple vascular territories in the frontal and temporal lobes. Occipital lobes often spared. Temporal lobe classic
Alzheimers Dementia
Most common cause.
Tauopathy, neurofibrillary tangles, amyloid cascade.
Risk factors: Age. Downs syndrome get this early.
See hippocampal atrophy. Temporal horn atrophy >3mm in 65% cases.
FDG shows low posterior temporoparietal uptake (earmuff). Posterior cingulate first affected.
Multi-infarct Dementia (Vascular Dementia)
2nd most common and aka Vascular Dementia
Risk factors: HTN, smoking, poor diet. CADASIL
See cortical infarcts and lacunar infarcts. Brain atrophy advanced for age
FDG multiple scattered areas of decreased activity. No specific lobar predominance.
Can knock out motor strip (others dont).
Dementia with Lewy Bodies
3rd most common
Alpha synuclein and synucleinopathy buzzwords
Visual hallucinations, spontaneous Parkinsonisn, fluctuating ability to concentrate/stay alert. Clinical picture similar to Parkinsons but major difference is dementia comes BEFORE Parkinsonism.
See mild generalized atrophy without lobar predominance. Hippocampi normal in size.
FDG decreased uptake in lateral occipital cortex with sparing of mid cingulate gyrus.
Picks Dementia (Frontotemporal Dementia)
Onset is earlier, 40s.
Classic presentaiton is compulsive or innapropriate behaviours. Think being a PrICK (PICKs)
Severe symmetric atrophy frontal lobes, milder in temporal lobes.
FDG low uptake in frontal and temporal lobes
Nerodegeneration disorders
FAHR DISEASE
Extensive calcification basal ganglia and thalamus. Mostly asymptomatic.
HALLERVORDEN SPATZ
Iron in globus pallidus. Also called PKAN. T2 dark globus pallidus with central bright area of necrosis “eye of the tiger”. No enhancement or restricted diffusion.
AMYOTROPHIS LATERAL SCLEROSIS
Upper motor neuron loss in brain and spine. Most die within 5 years. No gross volumeloss. T2/Flair normal. Motor band sign on gradient
CORTICOBASAL DEGENERATION
Tauopathy. Alien limb phenomenon. Symmetric frontoparietal atrophy
HUNTINGTON DISEASE
AD repeat sequence 38 CAG. Caudate atrophy and reduced FDG uptake. Frontal horns become enlarged and outwardly convex
LEIGH DISEASE
Mitochondrial disorder. ELevated lactate peak. T2/Flair bright in brainstem, basal ganglia and cerebral peduncles. Do not enhance.
Neurodegeneration disorders cont
MELAS syndrome
Mitochondrial disorder. Lactic Acidosis Seizures and Strokes. Elevated lactate. Atypical strokes in cotical gray matter with nonvascular distribution. Underlying WM is normal
HURLER SYNDROME
Mucopolysaccharidoses/lysosomal storage disease. Macrocephaly with metopic beak. Enlarged perivascular spaces. Beaked inferior L1 vertebral body
Parkinsons Disease
Resting tremor, rigid/slow movements (shuffling gait). Reduced dopaminergic input into striatum.
Cant diagnose on CT/MRI alone but possibly mild midbrain volume loss with butterfly pattern.
Nuke scan DAT ioflupane 123. Sparing of midbrain and superior cerebellar peduncles
Multiple System Atrophy (MSA) - a Parkinson Plus Syndrome
Complex entity, 3 subtypes
Cerebellar subtype shows cerebellar hemisphere/peduncle atrophy with a shrunken flat pons and enlarged 4th ventricle. Hot cross bun sign on axial imaging with loss of transverse fibres.
I-123 MIBG can differentiate PD from MSA by looking at cardiac/mediastinal ratio, normal in MSA, abnormal in PD
Progressive SUpranuclear Palsy (PSP) - a Parkinson plus syndrome
Most common Parkinson plus. A tauopathy.
Micky Mouse sign - tegmentum atrophy with sparing of tectum and peduncles.
Hummingbird sign - midbrain volume loss with concave upper surface and relative sparing of pons
Wilsons Disease
AR copper metabolism malfunction. Once liver fills with copper it spills over into brain. Kayser Fleisher rings seen 95%.
CT shows cortical atrophy. MRI shows T1 and T2 bright basal ganglia with T2 bright dorsal medial thalamus
Panda sign has T2 bright tegmentum with normal dark red nuclei and substantia nigra
Deep Brain Stimulators
Treatment of Parkinsons, essential tremor and chronic ain
For PD, electrodes are in subthalamic nucleus with tips located 9mm from midline, just inside upper most margin of cerebral peduncle
MRI spectroscopy
Various metabolites exist in different concentrations depending on pathology.
NAA (N acetyl aspartate) is a neuronal marker so things that destroy neurons will lower NAA. Lower NAA = higher grade tumour.
Choline is marker of cell membrane turnover. High value means high grade tumour, demyelination, inflammation.
Creatinine is marker of energy metabolism. Decreased in tumour necrosis.
Lactate product of anaerobic metabolism. Elevated in abscess or if tumour has outgrown blood supply.
PPM is parts per million. Each metabolite has a value for this.
Hunters Angle. on graph with intensity on y and ppm on x. Hunters angle should go from low to high in normal setting. Choline then creatanine then NAA.
DEmyelinating vs DYsmyelinating
DEMYELINATING
Example MS. Destroys myelin
DYSMYELINATING
Example metachromatic leukodystrophy. Disrupts normal formation and turnover of myelin.
Leukodystrophy - classic
Deficiencies in lysosomal storage disease, peroxisomal function or mitochondrial dysfunction. Target white matter, more symmetric and extensive. Untreatable and fatal.
ADRENOLEUKODYSTROPHY (ALD)
Normal head size. Parieto-occipital. Extends accross splenium. Enhance and restrict. Male predominant
METACHROMATIC
Normal head size. Frontal predominant. Periventricular and deep white matter. Tigroid (stripes) appearance. Most common. U fibres spared.
ALEXANDER DISEASE
Big head. Frontal predominant.Can enhance.
CANAVAN DISEASE
Big head. Bilateral subcortical U fibres. Elevated NAA
KRABBE
Small head. Centrum semiovale parieto-occipital predominant. Spares subcortical U fibres
PELIZAEUS MERZBACHER
Normal head size. Diffuse total lack of normal myelination with extension to U fibres. No enhance, no restrict.
Leukodystrophy - mitochondrial disease
Asymmetric, favours gray matter. Gray matter needs more oxygen than white matter and mitochondrial disorders are inability to process oxygen.
MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke like symptoms)
Parieto-occipital distribution. ‘migrating infarcts’
LEIGH DISEASE
Subacute necrotizing encephalomyopathy. Basal ganglia and periaqueductal gray matter. Normal head size.
Enhancement
ENHANCE
If extra axial or if blood brain barrier compromised.
Menigiomas or high grade tumour/infection.
Exceptions are low grade tumours Ganglioglioma and Pylocytic Astrocytoma
Intra vs Extra Axial
EXTRA-AXIAL CSF cleft. Displaced subarrachnoid vessels Cortical gray matter between mass and white matter Displaced/expanded subarrachnoid spaces Broad dural tail Bony reaction
Cerebral Metastases trivia
Most common CNS met in kid is neuroblastoma (bones/dura/orbit not brain)
Most common location is supratentorial GW matter junction - lots of blood flow and abrupt change in vessel calibre
Most common morphology round/spherical
50% solitary masses are mets
MRCT is bleeding mets (melanoma, renal, choriocarcinoma/carcinoid/thyroid)
Mets have more edema than a primary of same size normally
Multiple tumours
MULTIFOCAL Metastases Lymphoma Multicentric GBM Gliomatosis Cerebri
MULTIFOCAL FROM SEEDING Medulloblastoma Ependymoma GBM Oligodendroglioma
Syndromes
NF1
Optic Gliomas and Astrocytoma
NF2
Schwannomas, Meningiomas, Ependymomas
TUBEROUS SCLEROSIS
Subependymal Tubers
Intraventricular Giant Cell Astrocytoma (SEGAs)
Also AMLs
VON HIPPEL LINDAU
Hemangioblastomas
