Alien hand phenomena: a review with the addition of six personal cases.

This is a comprehensive literature review of the motor abnormalities that have come to be included under the designation of Alien Hand Phenomena (AHP). Some of the disorders are dyspractic in nature - intermanual conflict, mirror movements, interference etc., while others - groping, grasping with inability to release, utilization etc. are frontal lobe reflexes. AHP are mainly associated with two pathological processes: 1) Infarction or hemorrhage in the territory of the anterior cerebral arteries; and 2) Corticobasal degeneration. Included in the review is a description of AHP in six personal cases of corticobasal degeneration. The summary includes a short discussion of the possible anatomy of 'free will' based on AHP.