Callosal ideomotor apraxia in Alzheimer's disease

Abstract

Background/objective: Impaired ability to perform skilled movements with the left upper limb in patients with corpus callosum injury has been well described (callosal apraxia) with some displaying spatial-temporal errors primarily in response to verbal commands (verbal callosal disconnection apraxia), with imitation, and when using actual tools (callosal ideomotor apraxia). Additionally some patients with callosal injury also make content errors when selecting and using the incorrect tool with their left upper limb (callosal conceptual apraxia). Interestingly, patients with Alzheimer's disease (AD) reveal anatomic evidence of callosal degeneration but callosal apraxia in AD has not been described. The purpose of this study was to learn whether patients with AD display forms of callosal apraxia.

Method: Participants were 22 right-handed patients with AD and 24 matched controls. Both upper limbs were tested by having subjects pantomime transitive movements to command and imitation. Participants also viewed pictures of an incomplete task and attempted to pantomime the action needed to complete the task.

Results and conclusions: When compared to controls, the participants with AD demonstrated ideomotor and conceptual apraxias of both upper limbs; however, ideomotor apraxia of their left hand was more robust than that of their right hand, suggesting a hemispheric disconnection.

Keywords: Alzheimer’s disease; Apraxia; Corpus callosum; Disconnection.