Near-total absence of the cerebellum

We report five cases of near-total absence of the cerebellum with accompany ing pontine hypoplasia. The cerebellar remnant in each case comprised only antero-superior masses, the posterior fossa being otherwise fluid filled. T hree of these patients, two teenagers and an infant, presented a fairly con sistent clinical and neuroradiological phenotype, and a few similar cases a re recorded in the literature. The cerebellar remnant was irregular and asy mmetrical, and no ventral pontine prominence was discernible, In at least t he older two, cerebellar motor functions were not greatly compromised, and intellectual handicap was of a mild degree. We propose that these cases rep resent a distinct entity of "near-total absence of the cerebellum with flat ventral pens, and relatively mild clinical affection". All cases have been sporadic, implying that the risk of recurrence within a family may be low. Quite different clinical pictures, of considerably greater severity, are d emonstrated in the remaining two cases. One had pontocerebellar hypoplasia type 2, while the other had a complex cerebellar and cerebral malformation.