Presentation
Abnormal unsteady gait, speech difficulty, and mental retardation.
Patient Data
MRI study shows a relatively large head (macrocephaly) with evidence of diffuse fairly symmetrical and homogeneous white matter hyperintensity in the T2-weighted images, which involves the subcortical U-fibers with relative sparing of the corpus callosum, basal ganglia, and thalami, associated with bilateral subcortical cysts affecting the anterior poles of the temporal lobes. The DWI and ADC maps show no evidence of restricted diffusion, with no contrast enhancement seen in the contrast-enhanced study. The MRS shows a marked reduction in the NAA peak and other metabolites.
Case Discussion
Megalencephalic leukoencephalopathy with subcortical cysts is a rare autosomal recessive disorder associated with mutations in the gene encoding MLC1 protein, HEPACAM, and GlialCAM, which play a role in homeostasis in the myelin sheath. It usually presents in early life with macrocephaly, ataxia, and epilepsy. Later in life, the patient may develop slowly progressive spasticity, dysarthria, and cognitive impairment. The brain MRI study typically shows diffuse bilateral symmetrical abnormal high T2 white matter signal, involving the U-fibers, with relative sparing of the basal ganglia and thalami, in addition to the development of subcortical cysts, typically in the anterior temporal lobes, which are highly suggestive of this disease. Differential diagnoses include Canavan disease, vanishing white matter disease, and other causes of leukodystrophy.
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