ALIEN HAND SYNDROME - INTERHEMISPHERIC MOTOR DISCONNECTION DUE TO A LESION IN THE MIDBODY OF THE CORPUS-CALLOSUM

The neuroanatomic substrate of the alien hand syndrome has remained co ntroversial due to the noncircumscribed nature of cerebral injuries pr esent in most cases. There have been few cases studied in which damage was restricted to portions of the body of the callosum, and most of t hose involved surgical callosotomy for tumors or epilepsy. We report t he case of a woman with a transient alien hand syndrome caused by a st roke limited to the middle and posterior portions of the body of the c orpus callosum. This case provides supportive evidence for damage to t he midbody of the corpus callosum as the anatomic basis of nondominant alien hand syndrome and conforms to a model of interhemispheric motor disconnection as the essential component of this unusual behavioral s yndrome. This disconnection can occur with injuries involving interhem ispheric premotor and motor fibers traveling in the midportion of the callosum in individuals with left hemisphere dominance for motor activ ities.