Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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June 29, 2017
Megalencephalic Leukoencephalopathy with Subcortical Cysts (MLC) 1 in an Adult
- Background:
- Rare autosomal recessive dysmyelination disorder with 2 genetic mutations attributed to it: MLC1 and HEPACAM.
- Clinical Presentation:
- The diagnosis was made provisionally based on clinical and radiologic findings and was confirmed by genetic testing, which in our patient revealed an MLC1 mutation.
- Typically, patients present with a variable degree of macrocephaly within the first year, followed by marked motor developmental delay seen in early childhood.
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Slow cognitive decline also ensues after a variable period of time, and early onset seizures that respond to therapy are often features.
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This diagnosis is therefore almost always made in the pediatric age group, with only a handful of adult cases in the literature.
- Key Diagnostic Features:
- Subcortical white matter cysts are invariably present at the anterior temporal poles and frequently seen at the superior frontoparietal convexities.
- There is diffuse cerebral white matter T2 hyperintensity, but with relative sparing of the internal capsules and corpus callosum.
- There is no correlation between severity of MR findings and clinical course of the patients.
- Cavum septum pellucidum and cavum vergae are seen in most patients with MLC1.
- Differential Diagnoses:
- Other diagnoses to consider include congenital CMV infection, where the related encephalopathy is clinically static, and vanishing white matter disease (VWMD), where the clinical deterioration is much more severe and typically leads to death in childhood. FLAIR signal suppression of the T2 white matter signal abnormalities are characteristic of VWMD.
- Treatment:
- Treatment is supportive and aimed at symptomatic reduction with seizure control and motor dysfunction.
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