[Obsessive-compulsive behavior (arithmomania). Atrophy of the caudate nuclei]

We report the case of a 56-year-old woman who died after a 2.5 years progressive course of behavioral disorders associating severe obsessive-compulsive counting with disinhibition. Neuropathological examination showed severe gliosis of the caudate nuclei whereas the lentiform nuclei and frontal cortex were not involved. In contrast with previous reports, this case lacked psychic akinesia which is usually combined with obsessive-compulsive behavior. It is a further illustration of how subcortical lesions can produce a frontal like syndrome. It suggests a fundamental role of the caudate nuclei in the control of behavior.