The "alien hand" syndrome (AHS) is an unusual response to brain injury.
Clinical features of the alien hand syndrome:
(1) The patient has uncontrolled, involuntary and/or automaton-like movements of a hand.
(2) The patient does not perceive that the hand belongs to him/her, but rather seems "alien".
Risk factors for the involuntary movements:
(1) fatigue
(2) anxiety
(3) an object being nearby
Conditions associated with the alien hand syndrome:
(1) damage to the corpus callosum, including a partial callosectomy
(2) medial frontal lobe lesions
(3) progressive supranuclear palsy
(4) posterior cerebral lesion (pre- and postcentral gyri, corticobasal degeneration)
AHS may be subclassified:
(1) frontal: reflexive grasping, groping and/or compulsive manipulation of tools affecting the dominant hand
(2) callosal: intermanual conflict during behaviors requiring dominant-hemisphere control, which may be viewed as a result of hemispheric disconnection
(3) mixed frontal and callosal
(4) posterior
Site of Damage |
Clinical Findings |
mesial frontal and anterior callosal (genu and rostral body) |
frontal AHS (contralateral) |
isolated damage to callosal midbody and isthmus |
callosal AHS |
medial frontal and extensive damage to corpus callosum |
mixed frontal and callosal AHS |
posterior cerebral lesion without damage to corpus callosum |
posterior AHS |
Specialty: Neurology