Neuro (2) Flashcards
CJD - progressive rapid dementia, ataxia, myoclonus.
MRI findings high T2/FLAIR
- putamen
- Caudate nuclei
+/- pulvinar thalamic nuclei (hockey stick). Varient CJD.
Important points - no white matter involvement, no enhancement and can cause diffusion restriction.
Huntington disease
MRI findings -
Caudate head atrophy
Compensatory frontal horn prominence
‘BOX’ like appearance
Parkinson’s - neuronal loss in substantial migration (pars compacta)
MRI - blurring of intermediate signal line separating two adjacent low intensity structures (pars reticulata of SN and RN)
DAT (Dopamine Active Transfer) - loss of uptake in posterior putamen. Loss of comma sign.
Wilson’s disease - disorder of copper metabolism
White matter atrophy
T2 high signal basal ganglia and thalami.
Describe pattern in Wilsons, Huntington, Parkinson, Wernicke’s.
Differentiate Progressive multi focal leukoencephalopathy (PML) - JC and HIV encephalopathy
Toxoplasmosis v Lymphoma in HIV patients
Cerebral tuberculosis - Can be difficult to differentiate from toxoplasmosis or lymphoma
Target lesions in corticomedullary regions
Can CALCIFY with treatment
Co-existent MENINGEAL ENHANCEMENT
Cryptococcus - yeast like fungus
Non enhancing low density lesions in basal ganglia
These show high signal on T2
Differentiated from VR spaces on FLAIR where VR spaces suppress.
Can get a granulomatous meningitis.
Functional Imaging in Dementia
Tc99 HMPAO SPECT + FDG PET
FDG PET preferred
1.Alzeimhers - Disproportionate effect to anterior temporal lobes, hippocampi + Sylvia’s fissure. Reduced uptake precuneus + posterior cingulate gyrus + frontal/temporal parietal lobes. Sparing of occipital lobes.
3.Lewy body - SPARES hippocampi. Involves occipital cortex. Preservation of metabolism in mid-posterior cingulate gyrus. Affects temporal-parietal region.
2.Vascular dementia
Toxic Poisoning
Typically produces high T2 signal in basal ganglia (and low T1)
Methanol - Putamen
Carbon monoxide - Globus pallidus
Cerebral amyloid angiopathy (CAA)
- 1/3 pts over 60
- beta-amyloid protein deposition
-causes microhaemorrhage _ blooming artefact on T2*/SWI
Generally involves cortical/subcortical regions
Spares deep white matter and basal ganglia.
Chronic hypertensive encephalopathy
-end arteries affected - thalamic and lenticulostriate perforators
Stages of MS
1. Oedematous peri-vascular inflammation
2. Demyelination with proliferation of astroglia in chronic phase
Causes oblong elliptical plaques high callososeptal T2 signal
Other high yield
1.middle cerebellar peduncle is highly specific
2. Lesions can cross midline
3. T2>FLAIR in post. Fossa
4. Acute lesion can enhance (incomplete ring) + diffusion restrict
Thalamic involvement rare - think ADEM
Neurocysticercosis - Tapeworm infection carried by pigs.
Particular involvement of the basal ganglia
Cause rice like calcification on plain film. Orientated along the muscle fibres.
Stages - note 1) cyst in a dot, 4)calcification 1-10yrs.
Sheehan syndrome - consequent on obstetric hypovolaemia. Pituitary becomes atrophied.
Pituitary apoplexy
- pituitary infarction which can be secondary to haemorrhage (>50% patients have underlying macro adenoma)
- can cause empty sella sign in chronic stage
Sheehan - pituitary apoplexy secondary to hypovolaemic shock post delivery
Acute idiopathic transverse myelitis (diagnosis of exclusion)
- inflammation of spinal cord which results in motor, sensory and autonomic dysfunction.
- High T2 centrally expanded cord over multiple vertebral levels. At least 2/3 cord.
MS spinal plaques - confined to 1-2 vertebral levels. Confined to 1-2 vertebral levels. <1/2 cord cross section. High T2.
ADEM - days/weeks after viral infection
Mostly white matter but spinal cord can be affected. Grey matter in basal ganglia also.
Usually affects young children - respond well to steroid.
ADEM
Neurodegeneration with iron accumulation
(HAllervorden - Spatz syndrome)
Eye of tiger sign
Low T2 in globus pallidus
Tuberculosis meningitis v Sarcoidosis meningitis
- sarcoidosis shows nodular enhancement
Carcinomatous meningitis usually from breast ca (also lung, melanoma) - zuckergrass ‘sugar’ coating with thin subarachnoid enhancement following Gyral pattern
-also shows leptomeningeal nodularity.
HIV related brain disease
CADASIL
Cerebral autosomal arteriopathy with subcortical infarcts and leukoencephalopathy
30-50s
Recurrent TIA/stoke + depression/psychosis
Classically affects anterior temporal lobe and external capsules.
Moyà Moyà
Unilateral progressive occlusion/arteritis distal ICA
- large network of tiny collateral vessels on angiogram
-puff of smoke.
Herpes simplex encephalitis
T2 high signal unilateral white matter medial temporal lobe and insular region.
Also has a predilection for limbic system too.
It can diffusion restrict (differentiates it from Japanese encephalitis)
differential is low grade glioma.
AUTOIMMUNE AND LEIGH’S SYNDROME
Superficial Siderosis
Haemosiderin deposition pliable an depends all surfaces.
Secondary to recurrent SAH.
Congenital Infections - TORCH
CMV (most common) —peri-ventricular calcification+ polymicrogyria.
Toxoplasmosis —2nd, basal ganglia calcification and hydrocephalus.
Cavernous
POPCORN appearance on MRI - bright lobulated centre with a rim of hypo intensity.
Haemosiderin - blooming artefact.
No enhancement because slow flow in the lesion.
No mass effect, no oedema.
Subacute degeneration of the cord
-B12 DEFICIENCY
-dorsal inverted V shape
- patients have loss of position sense, vibration sense and sensory ataxia.
Toxic
Stellar/ Suprasellar masses
- Pituitary apoplexy
- Rathke cleft cyst
- Craniopharyngioma
Pituitary apoplexy - infarction (+/- haemorrhage). Most have macroadenoma. Acute phase can be T1 bright (blood). Chronic appearance - empty sella.
Rathke cleft cyst - between ant. + post pituitary.T2 bright. Mural enhancement.
Craniopharyngioma - child (adamantinomatous), adult (papillary). Lobulated, mixed cystic/calcified. Cholesterol rich. Avid enhancement. Kids calcify more often.
High T1 signal
Melanin, protein, contrast agent, fat, methaemaglobin (subacute haemorrhage)
Cerebellopontine angle lesions
- schwannoma, meningioma, epidermoid, arachnoid cyst.
Cavernoma / cavernous haemangioma
Popcorn appearance on MRI - bright lobulated centre with hypointense rim.
Haemosiderin deposition causes blooming artefact.
No enhancement on post contrast CT - slow flow within lesion.
Lesions which cross the midline/corpus callosum
GBM, lymphoma, infarction, trauma, radiation, metastases, MS.
Medulloblastoma v ependymoma.
Medulloblastoma -hypointense mass region of fourth ventricle on T1, heterogenous T2.
Homogenous enhancement and hypointense rim post-gad.
Parinaud syndrome is name given to symptoms caused by tectal plate compression - paralysis of vertical gaze (can be caused by pineal lesion)
Tulip phenomenon - vertigo + nystagmus induced by loud noise — SSCC dehiscence.
Gradenigo syndrome - otitis media, abducens palsy, V1 pain. Related to petrous apicitis.
Lateral medullary syndrome (Wallenberg)
- lateral medulla oblongata infarction supplied by PICA.
— ipsilateral stabbing facial pain, contra lateral loos of pain/temp sensation and ipsilateral bulbar weakness.
Superficial siderosis - Haemosiderin deposition over pial and ependymal surfaces.
Can cause ataxia if affecting cerebellum.
Caused by recurrent SAH.
Multisystem atrophy
- cerebellar atrophy
- ‘hot cross bun’ sign T2 hyperintensity shape of a cross at level of pons.
Vernet syndrome
Pathology at the jugular for amen affecting CN IX, X, XI
Carcinomatosis meningitis
Commonly derives from breast Ca (also lung ca + melanoma)
- zuckerguss - subarachnoid enhancement follows gyral convolutions. Leptomeningeal nodularity also.
Brown fat
The good fat - eskimos, igloo dwellers
Supraclavicular fossa
PET - CT high signal
Nephrogenic systemic fibrosis
Nasty condition
Develops weeks/months after Gad in patients with acute/chronic renal failure.
Dyspnoea is a described feature,
Limbic encephalitis - Bronchial small cell lung cancer
Limbic system - olfactory tract, temporal lobes, cingulate gyrus, insular cortex.
Can be paraneoplastic or autoimmune.
Involvement of mesial temporal lobes is classic.
Psychotic symptoms differentiate limbic from HSV encephalitis.
Meningioma vs orbital pseudotumour.
Meningioma - TRAM TRACK sign — optic sheath enhancement post contrast.
Optic neuritis - high T2 signal within the optic nerve.
Orbital pseudotumour — IGG4 related — affects any part of eye (usually spares optic nerve)
Optic nerve glioma - causes kinking or buckling of optic nerve.
Hemangioblastoma
Raised haematocrit secondary to polycythaemia.
Part cystic/ part solid lesion with enhancing mural nodule. Contact with pial surface.
Vanishing tumour
Primary CNS lymphoma
- will dramatically reduce with steroids
Pineal gland masses
More cystic a mass is the less agreesibe
Pineal cyst
Pineocytoma
Pineoblastoma
Germinoma - solid masses which engulf calcification.
Intracranial haemorrhages
Superior quadrantanopia - temporal lesion, Meyers loop
Inferior quadrantanopia - parietal lesion, Dorsal optic tract
Superior sagittal sinus thrombosis
Empty delta sign on POST CONTRAST CT
Low T1 signal , blooming artefact.
Dense triangle would indicate acute thrombus
subclavian steal syndrome
-flow reversal in the vertebral artery, biphasic flow in the axillary
Blood supplying the arm (normally left), via ipsilateral vertebral artery. Distal subclavian steals blood from the vertebral artery circulation.
Causes
1. Atherosclerosis
2. Cervical rib
3. Takayasu aortitis
4. Aortic dissections
Intracranial Blood on MRI
PRES
Posterior reversible encephalopathy syndrome
Vasogenic and reversible oedema normally occipital lobes
Grey white matter interface is preserved.
Classic - visual disturbance, postpartum with pre-eclampsia. CT shows posterior fossa haemorrhages.
Carotid-cavernous fistula
Painful left eye swelling
Third nerve palsy
Prominent superior ophthalmic vein
Causes of Horner syndrome
Sickle sign or fried egg sign
Refers to the appearance on T1 fat sat sequences of hyper intense crescentic shape in affected vessel.
Idiopathic intracranial hypertension
V
Sagittal sinus thrombosis
Brown-Sequard syndrome
-ipsilateral loss of touch + contralateral pain/temperature (spine thalamic tract). Ipsilateral motor function loss.
Causes:
Trauma
Vascular - AAA repair complication. VA dissection. Spinal cord haemorrhage.
Spinal cord infarct -
T2 high grey matter if not whole cord
Diffusion restriction
Adjacent vertebrae can infarct
Anterior spinal artery
Adamkiewicz - T9 lumbar
Subacute combined degeneration - inverted V
B12
Position, vibration sense.
Wallenburg
Lateral medullary syndrome
