Extrinsic infratentorial lesion causing ataxic hemiparesis--a new localization.

The case of an 18-year-old woman is reported who had developed progressive inability to use her left limbs since the age of 13 years. Ataxic hemiparesis was noted on the left side. A CT scan of the brain revealed a non-enhancing hypodense lesion in the cerebellopontine angle with a supratentorial extension consistent with an epidermoid. Ataxic hemiparesis has previously been reported only with intrinsic lesions of the brain, except for one case. An unusual clinical localization of this entity is reported.