Fukuyama congenital muscular dystrophy MRI

Clinically: Floppy infant / hypotonia.

MRI findings:

Bilateral frontal Polymicrogyria.

Diffuse cerebral cortical atrophy marked in bilateral frontal and temporal lobes.

Bilateral temporo occipital white matter show patchy T2 hyper intensity suggestive of associated dysmyelination, bilateral hippocampal Mal orientation, ex vacuo dilatation of temporal horns of lateral ventricles.

Associated hypoplasia of corpus callosum.

Poorly pneumatised of paranasal sinuses and mastoid air cells.

Micro crania, brachycephaly, small posterior fossa.

Brainstem atrophy, mid line cleft on ventral aspect of Pons.

No associated cerebellar dysplasia. Ill-defined mid line vermis.

Impression:

Imaging diagnosis: Fukuyama congenital muscular dystrophy more likely than Walker Warburg syndrome as there is no associated cerebellar dysplasia.

Fukuyama congenital muscular dystrophy

Named after Yukio Fukuyama (1928-2014), a Japanese pediatric neurologist, who first described the condition in his 1960.

Exclusively found in Japan with an incidence of 2/4 per 100,000 infants and is the second most common muscular dystrophy after Duchenne muscular dystrophy.
Affected infants are hypotonic, generalised symmetric weakness affecting extremities and facial muscles by 1 year.
Accompanied by developmental delay and intellectual disability afterwards with epilepsy.

An autosomal recessive inherited disease due to a mutation in the fukutin-related protein (FKTN) gene.

Classic MRI brain features are polymicrogyria typically in the frontal and parietal lobes.Pachygyria in approximately half of patients, typically involving the temporal and occipital lobes.
Cerebellar polymicrogyria is seen in approximately 90% of patients. White matter changes patchy, spotty suggestive of dysmyelination.
Walker-Warburg syndrome is one of its main differentials, in which cerebellar dysplasia is commonly seen is not very common in Fukuyama congenital muscular dystrophy

Definitive treatment not available.

Crossed cerebellar diaschisis

Clinical presentation: Frequent seizures, altered sensorium. 

MRI brain shows marked left hemi Atrophy, ex vacuo dilatation of left lateral ventricle owing to volume loss. Left cerebral hemisphere show multifocal patchy areas of cortical T2 hyper intensities without diffusion restriction. Associated Atrophy of left deep grey nuclei, changes of distal Wallerian degeneration involving left cerebral peduncle of mid brain, Pons.

Imaging diagnosis: Sequel of encephalitis / rasmussen encephalitis.

Right cerebellar hemisphere show marked atrophy can attributed to associated contralateral cerebellar diaschisis. 

Crossed cerebellar diaschisis

Refers to supra tentorial lesion leading to depressed function, metabolism and perfusion of contra lateral cerebellar hemisphere which is connected via white matter tracts.
Interruption of this cortico-ponto-cerebellar white matter tracts which then results in deafferentation and hypometabolism of the contralateral cerebellar hemisphere.

Classically seen following cerebral infarction, although it can be a sequel of any significant supratentorial lesion like bleed, encephalitis as in our case. The same phenomenon can also occur in thalamus called ipsilateral thalamic diaschisis, occurring after an ipsilateral middle cerebral artery territory infarction.

CT or MRI perfusion performed during an acute stroke may show a contralateral cerebellar hypo perfusion. In chronic stages volume loss involving contralateral cerebellar hemisphere.

Clinically other than the neurological deficits associated with the contra lateral supra tentorial lesion, the condition is generally asymptomatic. No treatment apart from management of the supratentorial insult.

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