Dr. Strangelove demystified: Disconnection of hand and language dominance explains alien-hand syndrome after corpus callosotomy

Background: Alien hand syndrome (AHS) is a disabling condition in which one hand behaves in a way that the person finds alien. This feeling of alienation is related to the occurrence of movements of the respective hand performed without or against conscious intention. Most information on AHS stems from single case observations in patients with frontal, callosal, or parietal brain damage. Methods: Retrospective analysis of distinctive clinical features of three out of 18 epilepsy patients who developed AHS with antagonistic movements of the left hand after corpus callosotomy (CC) (one anterior, two complete) for the control of epileptic seizures, particularly epileptic drop attacks (EDA). Results: Remarkably, these three patients, two men and one woman, displayed atypical language dominance with a bilateral, left more than right hemisphere language representation in intracarotidal amobarbital testing before surgery. The overall additional distinctive feature of the target patients was genuine left-handedness, with writing retrained to right-handedness in two patients. After surgery the left hands became alien. The problem was permanent, despite strategies for compensation. Conclusion: From this observation we suggest that under the conditions of dissociation of language and motor dominance, loss of both intentional control of contralateral action and physiological inhibition of antagonistic movements lead to post-callosotomy alien-hand-like motor phenomena. The dissociation pattern posing this risk seems rare but needs to be considered when evaluating candidates for callosotomy.

Automated summary

This study retrospectively analyzed distinctive clinical features of three epilepsy patients who developed Alien Hand Syndrome (AHS) after corpus callosotomy for the control of epileptic seizures. The patients displayed atypical language dominance with bilateral hemispheric representation and genuine left-handedness. The problem of AHS in these patients was permanent despite compensation strategies, indicating a rare dissociation pattern needing consideration in callosotomy candidates.