Practice writtens Flashcards
Carotid artery ultrasound parameters
PSV < 125 cm/s ICA
ICA:CCA (PSV) <2
50-69% - Ratio 2-4, PSV 125-230
>69% >230, >4
Subclavian steal
Phenomenon is reversed vertebral flow from proximal SCA stenosis.
Syndrome is above plus neuroischaemic symptoms
Also arm weak pulse and claudication
Mostly from atherosclerosis but can be from vasculitis
MR spectroscopy
NAA peak, choline peak
NAA is brain tissue, choline neoplasia (easy way to remember)
As grade of tumour increases, NAA decreases, and choline increases.
All low in radiation change
Lactate increased in infarction
All processes which destroy brain tissue have absent NAA.
Choline low or absent in toxoplasmosis, elevated in lymphoma.
Canavan disease
A leukodystrophy Death before 5, often before 18 months Ashkenazi Jews Autosomal recessive Acumulation of NAA CaNAAvan Megalencephaly Diffuse white matter disease Involves subcortical U fibres No enhancement
Leukodystrophies
dysmyelinating diseases which affect children
Lysome storage (MPS - Hurlers, Morquio, Neimann Pick, metachromatic leukodystrophy, Fabry disease)
Mitochondrial dysfunction (MELAS, Leighs, other)
Peroxisomal (Zellweger - cerebrohepatorenal syndrome, adrenoleukodystrophies - X-linked, involes splenium, and testes and adrenals)
Amino acid metabolism - Canavan
MLC, Alexander disease
Metachromatic leukodystrophy
The most common leukodystrophy (dysmyelination)
A lysosome storage disorder
Reduced NAA, increased lactate
Tigroid sparing of venules
Subcortical U fibre sparing - butterfly pattern
Autosomal recessive
Infantile, juvenile and adult forms
Motor, sensory, or psychiatric
Diffuse white matter disease
See core or other textbooks, to work on differential (See leukodystrophies listed above, see which are listed in textbooks therefore essential)
Leptomeningeal enhancement
Neoplastic - lymphoma, breast, lung, melanoma Inflammatory - neurosarcoid, Meningitis inc tb Collaterals e.g. moyamoya, infarction Post uncomplicated LP (rare, 5%)
MLC
Megalenchephalic leukoencephalopathy (with subcortical cysts)
Van der Knaap disease
AR
White matter cystic degeneration and megalencephagly
T2 increased white matter with sparing of basal ganglia
Subcortical cysts of CSF intensity anterotemporal and frontoparietal
Antiepileptics to manage epilepsy
Mild motor delay, mild mental deterioration
Alexander disease
Fibrinoid leukodystrophy Sporadic Anterior dominant, extends posteriorly Basal ganglia become involved Normal NAA Fatal Infantil, juvenile, and adult forms. Enhancement may be seen
Megalencephaly and white matter disease
MLC, Alexander, Canavan
(Adrenoleukodystrophy and metachromic lyuekodystrophy both spare subcortical U fibres)
Megalencephaly means large brain cf macrocephaly. In general associated with syndromes.
MR spectroscopy, normal peaks
Left to right
Choline, creatine, NAA
Lactate to the right of all of these - elevated in necrosis and infection. Also can be in DAI, associated with poor prognosis
Creatine usually slightly higher than choline, with NAA about twice the other two
Cerebellar atrophy
Phenytoin toxicity
Paraneoplastic - small cell lung commonly
ETOH
Seizures
Endolymphatic sac tumour
Rare tumour, locally invasive
Associated with VHL
CJD
Can diffusion restrict
