Cerebellar agenesis

Abstract

Cerebellar agenesis is an extremely rare condition in which patients show minute cerebellar tissue, usually corresponding to remnants of the lower cerebellar peduncles, anterior vermal lobules, and flocculi. Clinical presentation of cerebellar agenesis may cover a broad phenotypic spectrum of disabilities including not only motor disorders but also cognitive abilities, language disabilities, and disorders of affect. Severity and range of motor, cognitive, and psychiatric impairments appears to be correlated with earliness, localization, and extent of the agenesis of cerebellum. Patients with congenital malformations present indeed a more severe and less specific impairment than patients with acquired cerebellar lesions in adult life. Patients with involvement of the phylogenetically most ancient structures (complete or partial cerebellar vermis agenesis) show the more severe clinical picture, in particular severe pervasive impairments in social and communication skills (autism or autistic-like behavior), in behavior modulation (self-injury and aggressiveness), and markedly delay in language acquisition, especially in language comprehension. On the contrary when the lesions are confined to phylogenetically more recent structures, such as cerebellar hemispheres, the clinical picture is characterized by mild cognitive impairment or borderline IQ, good social functioning, and context adjustment abilities with a more favorable prognosis. In conclusion, it is possible to argue that cerebellar agenesis, in spite of extraordinary neuroradiological picture, is a clinical condition compatible with an honorable existence, although limited, especially if the affected person has the opportunity to undergo a rehabilitation program at an early stage of his life.