Inborn metabolic brain disorders

Q.All are true regarding inborn metabolic brain disorders except

a. Alexander's disease shows  extensive white matter abnormality beginning in the frontal and periventricular white matter

b. l-2 hydroxyglutaricaciduria  involve   the periventricular white matter and corpus callosum

c. bilateral symmetrical involvement of the globus pallidus with sparing of the thalami is seen in methylmalonic acidaemia

d. Bilateral pallidal involvement is  seen as T2 hyperintensity  in Kearns–Sayer syndrome

e. Lorenzo's oil may delay disease progression of ALD

ANS .---b

The MRI findings of  l-2 hydroxyglutaricaciduria show white matter involvement with peripheral involvement, particularly of the subcortical U fibres, internal, external and extreme capsules, sparing of the periventricular white matter and corpus callosum, and with a slight frontal predominance. There is macrocephaly

Bilateral pallidal involvement is  seen as T2 hyperintensity in methylmalonic acidaemia ,GAMT (guanidinoacetate methyltransferase deficiency), Kearns–Sayer syndrome ,kernicterus and carbon monoxide poisoning

Rasmussen encephalitis

Q.All are true regarding Rasmussen encephalitis except

a. an abrupt onset of severe and intractable epilepsy

b. usually begins in childhood(6 and 8 years )

c. tends to affect hemisphere bilaterally

d. Serial scans show focal or hemispheric atrophy

e. cortical swelling with hyperintensity on T2W--earliest change on MRI--

ANS.----c

The disease tends to affect one hemisphere. Classification and staging criteria have been proposed based on MR imaging findings on T2-weighted and FLAIR images: normal volume and signal (stage 0), swelling and hyperintense signal (stage 1), normal volume and hyperintense signal (stage 2), atrophy and hyperintense signal (stage 3), and progressive atrophy and normal signal (stage 4).

Brain malformations

Q.All are true regarding  brain malformations except

a. The posterior fossa is of normal size in cerebellar hypoplasia

b. Torcular–lambdoid inversion on MRI is seen in Dandy –Walker

syndrome

c.  ‘batwing appearance’ of the fourth ventricle  is seen in Joubert's

 syndrome

d.The ‘Molar   tooth’ appearance is noted  in

rhombencephalosynapsis

 

e. a nonenhancing mass with diffusely enlarged cerebellar folia is 

feature of  L'Hermitte-Duclos
ANS.---d

Joubert's syndrome  is  considered  as generalized developmental disorder of the midbrain and hindbrain. The imaging findings reflect a failure of formation of the decussation of the superior cerebellar peduncles, lack of the pyramidal decussations and other anomalies of the midbrain crossing tracts and their nuclei. On cross-sectional imaging the fourth ventricle is enlarged with a ‘batwing appearance’ and there is a cleft in the vermis. The midbrain is small. The ‘molar tooth’ appearance seen on axial images arises from the lack of the superior cerebellar decussation and the superior peduncles also appear enlarged.

‘Snake eyes’ appearance within the spinal cord

Q.---All are true regarding degenerative changes of spine except

a.  The commonest site of protrusion is located  posterioriorly

b. type 1 reactive changes yield high signal on T1W and high on

 T2W

c. Ossification of OPLL involves the mid- and lower cervical region in over 90 % cases

d. Retro-odontal pseudotumour  refers to thickened transverse

 ligament of the atlas and associated ligaments

e. ‘snake eyes’ appearance within the spinal cord  on axial images

 is seen in   cervical spondylotic myelopathy

ANS.---b

Modic described three types of reactive changes in the cancellous bone adjacent to the vertebral end-plates: (type 1) in the acute stage of disc disease there is invasion of the cancellous spaces by fibrovascular reactive tissue; in time this leads to (type 2) fatty replacement of red marrow; eventually this leads to (type 3) bony sclerosis. These changes are exquisitely shown by MRI: (A) type 1 changes yield low signal on T1W and high on T2W; (B) type 2 changes yield high signal on T1W and T2W (unless fat suppressed, when they will yield low signal); (C) type 3 changes yield low signal on all sequences. 

Pelizaeus-Merzbacher disease

Q.All are true regarding Pelizaeus-Merzbacher disease except

a.due to lack of lipophilin

b.patchy demyelination with sparing of perivascular white matter

c.preserved internal capsule and subcortical U fibres

d.diffuse low signal on T2w

e.hypointense basal ganglia and thalamus on T2W

ANS.---d

Severe cases of Pelizaeus-Merzbacher disease show near –total 

lack of normal myelination with  diffuse high signal on T2W image

 that extends peripherally to involve the arcuate fibres .

LEUKODYSTROPHIES

Q.All are true regarding leukodystrophies except

a.complete or near complete lack of myelination is seen 

in Pelizaeus-Merzbacher disease

b.temporal lobe white matter is most involved in Alexander disease

c.occipital lobe white matter is most involved in 

adrenoleukodystrophy

d.thick meninges is seen in Hurler syndrome

e.high density basal ganglia is seen in Krabbe disease

ANS .---b

Frontal  lobe white matter is most involved in Alexander disease.

Complete or near complete lack of mylination is seen in Canavan

 disease and Pelizaeus-Merzbacher disease