Adrenoleukodystrophy

Findings:
Axial CT images show patchy diffuse posterior white matter hypodensity. Multiple MR images show predominant signal abnormalities in the parieto-occipital white matter and splenium of corpus callosum with symmetric enhancement along the periphery. The signal abnormalities extend into the brainstem.

Differential Diagnosis:
The signal characteristics are most consistent with ADL. Globoid cell leukodystrophy may also have predominant abnormalities in the parietal regions, but this characteristic enhancement pattern would be unusual. MS and ADEM could rarely have this appearance, and would not likely be this symmetric.

Discussion:
ADL represents a deficiency of lignoceroyl CoA ligase, with accumulation of very long chain fatty acids in brain, adrenals, and blood elements. It is inherited as x-linked recesive or autosomal recessive. Pathologically, there is demyelination which advances in zones, with the peripheral zone showing no inflammatory response. The intermediate zone has active demyelination and inflammatory response, with the inner zone showing necrosis, gliosis, and possible calcification. Numerous phenotypes exist, the most common of which has clinical onset between 5-10 years, with rapidly progressive neurologic decline and death. Imaging features include symmetric posterior white matter involvement including the splenium, with a rind of enhancement along the advancing edges. reference: Osborn, A; Tong, K. Handbook of Neuroradiology: Brain and Skull. 1996: Mosby Year Book. pp. 521-523.

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