Cognitive impairments in patients with congenital nonprogressive cerebellar ataxia

Objective: To report neuropsychologic functions and developmental problems of patients with congenital nonprogressive cerebellar ataxia. Background: Growing interest in cerebellar function has prompted closer attention to cognitive impairments in patients with cerebellar damage. Methods: The authors studied 11 patients with nonprogressive congenital ataxia (NPCA) with Wechsler's intelligence testing, with additional tests of attention, memory, language, visual perception, and frontal functions. Results: Seven of the 11 patients had an IQ of 60 to 92, with marked nonverbal deficits and subnormal to normal verbal performance (group A). Four patients had an IQ of 30 to 49 without pronounced profile asymmetry (group B). Four of the 7 group A patients had decreased alertness and sustained attention, but all had normal selective attention. Tests of frontal functions and memory yielded higher verbal scores than nonverbal scores. There was no deficit on the Aachener Naming Test (similar to the Boston Naming Test), because there were marked difficulties in the majority with visuoconstructive tasks and visual perception. Group B was significantly abnormal in almost all subtests, having a less prominent but similar profile. Conclusion: Patients with NPCA have significant cognitive deficits with an asymmetric profile and better verbal than nonverbal performance. Effects on nonverbal performance of longstanding deficits in visuospatial input during learning, the influence of impaired procedural learning, and asymmetric plasticity of the cerebral hemispheres may contribute to this uneven neuropsychological profile.