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Cases of cerebellar agenesis are rare. The degree of motor impairment is a matter of discussion. It has been claimed that normal motor function can be observed. Detailed descriptions of neurological findings, however, are lacking. Neuropsychological testing in cerebellar agenesis is of additional interest based on recent findings of impaired non-motor functions in cerebellar disease. The case of an elderly woman with cerebellar agenesis is presented. 3D-MR imaging was used to confirm the diagnosis. Neurological and neuropsychological examination was performed including video documentation (see the authors' own website). To assess deficits of motor learning eyeblink conditioning was investigated. Neurological examination revealed mild to moderate signs of cerebellar dysarthria, upper and lower limb ataxia and ataxia of stance and gait. Motor learning was affected as shown by inability to acquire conditioned eyeblink responses. In addition, neuropsychological testing disclosed mild to moderate deficits in IQ, planning behavior, visuospatial abilities, memory and attention. Cerebellar ataxia, although clearly present, was less than one would expect in almost complete absence of the cerebellum. Neuropsychological deficits, on the other hand, appeared to be more marked than one would expect in cerebellar disease. No conclusion, however, could be drawn whether impaired cognitive development and neuropsychological test performance were directly related to lack of cerebellar function, or caused by impaired motor development and performance.

. Children and adolescents with chronic cerebellar lesions show no clinically relevant signs of aphasia or neglect. J Neurophysiol 94: 4108 -4120, 2005. First published July 20, 2005 doi:10.1152/jn.00611.2005. We studied language and visuospatial functions of 12 children and adolescents who had undergone surgery for cerebellar astrocytoma without subsequent radiation or chemotherapy and compared them with 27 age-, gender-, and education-matched healthy control subjects. To study possible lateralization of the functions of the left and right cerebellar hemispheres, subjects performed several language tasks including a verb-generation task as well as standard neglect and extinction tests. Three-dimensional-MR images confirmed that lesions affected cerebellar hemispheres in all children but one who had a pure vermal lesion. The right cerebellar hemisphere was affected in six, the left hemisphere in four children, and both hemispheres in one child. There were no signs of aphasia in the children or adolescents with cerebellar lesions. Language abilities did not differ between cerebellar patients and control subjects except for small increases in reaction times in verb generation in patients with left-sided lesions. Visuospatial functions were also intact in cerebellar subjects except for minor group differences in neglect tasks. In sum, chronic focal cerebellar lesions acquired in childhood or youth do not result in persistent language disorders or clinically significant signs of spatial neglect or extinction.

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