APRAXIA DUE TO A PATHOLOGICALLY DOCUMENTED THALAMIC INFARCTION

We report a pathologically documented case of infarction of the domina nt thalamus with extensive involvement of the ventral lateral, ventral posterolateral, and lateral posterior nuclei and some involvement of the pulvinar. This patient exhibited linguistic impairment with featur es fairly typical for thalamic lesions. He also demonstrated a severe ideomotor apraxia. The preservation of repetition, syntax, and implici t memory despite severe naming deficits in patients with thalamic lesi ons suggests the possibility that thalamic involvement in cognitive fu nction involves processes underlying declarative as opposed to nondecl arative (eg, implicit or procedural) memory. The occurrence of apraxia with thalamic lesions may be consistent with this hypothesis if it is accepted that only actual tool use approaches a pure skill that invol ves only nondeclarative memory, while other aspects of praxis implicat e declarative memories.