Cranial ultrasound findings in aspartoacylase deficiency (Canavan disease)

Canavan disease (CD) is a rare leukodystrophy which is lethal in infancy or early childhood. The underlying biochemical abnormality in CD is a hereditary deficiency of N-aspartoacylase transmitted in an autosomal recessive fashion. We report on the ultrasound (US), CT, and MRI findings of three unrelated boys with biochemically confirmed CD. At 6 and 9 months of age, two CD patients with rapid neurological deterioration showed markedly enhanced acoustic attenuation of the white matter with the exception of the corpus callosum, giving the appearance of a reversed pattern of echogenicity of cortical gray and subcortical white matter. While gyri and sulci had an almost normal US appearance, the periventricular gray matter featured prominently with increased echogenicity. In contrast another CD patient with a more protracted course had ventricular enlargement when examined by US at 5 and 9 months but no alteration in white matter echogenicity. MRI showed impaired myelinization in all three patients with Canavan disease.