MACROCEREBELLUM - NEUROIMAGING AND CLINICAL-FEATURES OF A NEWLY RECOGNIZED CONDITION

Other than hamartomatous enlargement of the cerebellum as in Lhermitte -Duclos syndrome, diffuse enlargement of the cerebellum is not clearly described. We report four patients (ages 9 months to 2 years) with di ffusely enlarged cerebelli as identified by measurement of the cerebel lum and comparison to age appropriate normal values. The cerebellar me asurements were determined in absolute numbers and expressed as ratios of cerebellum to whole brain and supratentorial brain. The clinical f eatures of these four children (3 boys, I girl) consistently include g lobal developmental delay, tone abnormalities, preserved reflexes, del ayed or abnormal maturation of the visual system (oculomotor apraxia), and deficient or delayed myelination of cerebral white matter. The et iology of the macrocerebellum is unknown but we propose that the cereb ellum is responding to the elaboration of growth factors intended to a ugment the slow development of cerebral structures. Regardless of the etiology, the finding of a macrocerebellum appears to allow the clinic ian to predict the clinical features of the patient and probably repre sents a marker for disturbed cerebral development.