Abstract
The course of a patient affected by the phenomenon of "anarchic hand" (AH) is de scribed. The patient had an ischemic lesion involving the left frontomesial cortex and the corpus callosum with a transitory AH of the left hand and later a chronic right AH. The signs of callosal disconnection and the involvement of the supplementary motor area were reviewed, and various hypotheses as to the nature of the lesion that causes the AH phenomenon to appear and to last have been discussed. The hypoth esis that a callosal lesion is sufficient for the appearance of AH, but a supplementary motor area lesion contralateral to the involved hand causes the chronic AH syndrome. Key Words: Anarchic hand—Supplementary motor area—Corpus callosum—Cal— losal disconnection signs.