Alien Grasp Reflex
Definition and Clinical Features
The alien grasp reflex describes an involuntary, forceful grasping movement of the hand that occurs while the patient is fully conscious. The patient can often anticipate the movement but perceives it as "alien"—that is, not under their voluntary control. This phenomenon occurs in the absence of other abnormal movements.
The alien grasp reflex is an involuntary action perceived by the patient as if the hand is acting on its own, a sign of frontal lobe dysfunction.
Clinical Significance and Anatomical Basis
This phenomenon is associated with lesions in the frontal lobe, particularly intrinsic tumors of the right (nondominant) frontal lobe. The concept of the "alien grasp reflex" highlights the clinical overlap between a simple grasp reflex (a primitive reflex) and the more complex alien hand syndrome. It suggests that these are not entirely separate entities but rather exist on a spectrum of frontal lobe motor dysfunction.
References
Silva MT, Howard RS, Kartsounis LD, Ross Russell RW. The alien grasp reflex. European Neurology 1996; 36: 55-56
Cross References
Alien hand, Alien limb; Grasp reflex
