Expert Opinion :
This child has presented with cerebellar signs and signs of pyramidal tract involvement in form of hypertonia and brisk reflexes suggestive of white matter involvement. Hence one would consider a differential diagnosis of a fourth ventricle space occupying lesion (SOL) or a metabolic disorder that has involvement predominantly of white matter and the cerebellum such as an infantile variety of Neuronal Ceroid Lipofuscinosis (NCL) (presents with ataxia and seizures) or mitochondrial disease. Other white matter diseases such as metachromatic leukodystrophy, Krabbe’s disease, adrenoleukodystrophy are unlikely as they are associated with optic atrophy, peripheral neuropathy, and neuroregression. Familial varieties of cerebellar ataxia are unlikely as the age of onset is too early and there is no positive family history except for Marinesco-Sjögren (presents with mental retardation, cataract, hypotonia, myopathy) and infantile-onset spinocerebellar ataxia (presents with peripheral neuropathy, athetosis, optic atrophy, deafness, ophthalmoplegia) which present in infancy. However, the child does not seem to fit into any of these hereditary ataxias.
Thus in this child neuroimaging in form of MRI would be required to delineate the white matter changes. MRI brain showed cerebral and cerebellar atrophy with a hyperdense abnormality in the deep cerebral white matter at lateral ventricle margin suggestive of either NCL or mitochondrial disease.