Alien limb in the corticobasal syndrome: phenomenological characteristics and relationship to apraxia

David J. Lewis-Smith, Noham Wolpe*, Boyd C.P. Ghosh, James B. Rowe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Alien limb refers to movements that seem purposeful but are independent of patients’ reported intentions. Alien limb often co-occurs with apraxia in the corticobasal syndrome, and anatomical and phenomenological comparisons have led to the suggestion that alien limb and apraxia may be causally related as failures of goal-directed movements. Here, we characterised the nature of alien limb symptoms in patients with the corticobasal syndrome (n = 30) and their relationship to limb apraxia. Twenty-five patients with progressive supranuclear palsy Richardson syndrome served as a disease control group. Structured examinations of praxis, motor function, cognition and alien limb were undertaken in patients attending a regional specialist clinic. Twenty-eight patients with corticobasal syndrome (93%) demonstrated significant apraxia and this was often asymmetrical, with the left hand preferentially affected in 23/30 (77%) patients. Moreover, 25/30 (83%) patients reported one or more symptoms consistent with alien limb. The range of these phenomena was broad, including changes in the sense of ownership and control as well as unwanted movements. Regression analyses showed no significant association between the severity of limb apraxia and either the occurrence of an alien limb or the number of alien limb phenomena reported. Bayesian estimation showed a low probability for a positive association between alien limb and apraxia, suggesting that alien limb phenomena are not likely to be related to severity apraxia. Our results shed light on the phenomenology of these disabling and as yet untreatable clinical features, with relevance to theoretical models of voluntary action.

Original languageEnglish
Pages (from-to)1147-1157
Number of pages11
JournalJournal of Neurology
Issue number4
StatePublished - 1 Apr 2020
Externally publishedYes


FundersFunder number
Cambridge Brain Bank
Cambridge Centre for Parkinson-plus
National Institute for Health Research Cambridge Biomedical Research Centre
Raymond and Beverley Sackler Trust
James S. McDonnell Foundation
Wellcome Trust103838
Medical Research CouncilMC_UU_00005/12, G0700503, SUAG/004 RG91365


    • Alien limb syndrome
    • Anarchic hand syndrome
    • Apraxia
    • Corticobasal syndrome
    • Sense of agency
    • Sense of ownership
    • Volition


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