Unusual Neuroimaging Findings in Two Families with Giant Axonal Neuropathy.

An 8-year-old boy, born to a third-degree consanguineous couple with no adverse perinatal events, presented with complaints of delayed development and gait abnormalities. He had global developmental delay with independent ambulation achieved at two years of age and monosyllables at 2.5 years of age. There was no regression. His hearing and vision were normal. He had had two episodes of generalized tonic-clonic seizures in the previous year. His examination revealed normal fundus and absence of musculoskeletal deformities. He had frizzy hair, mild global hypotonia, no motor weakness, absent muscle-stretch reflexes, and positive cerebellar signs. He had an older male sibling (not investigated) with a similar illness who was now bedridden. Magnetic resonance imaging of the brain showed T2 hyperintensities in the bilateral cerebellar dentate nuclei, posterior limb of the internal capsule, and the globus pallidi (Figure 1). Nerveconduction studies were suggestive of sensorimotor axonal polyneuropathy. Nerve biopsy showed giant axons. Echocardiography was unremarkable.