Intended for healthcare professionals

Clinical Review

Locked-in syndrome

BMJ 2005; 330 doi: (Published 17 February 2005) Cite this as: BMJ 2005;330:406
  1. Eimear Smith (, specialist registrar in rehabilitation medicine1,
  2. Mark Delargy, consultant in rehabilitation medicine (
  1. 1 National Rehabilitation Hospital, Dun Laoghaire, County Dublin, Ireland
  1. Correspondence to: E Smith
  • Accepted 23 November 2004


The locked-in syndrome is caused by an insult to the ventral pons, most commonly an infarct, haemorrhage, or trauma. The characteristics of the syndrome are quadriplegia and anarthria with preservation of consciousness. Patients retain vertical eye movement, facilitating non-verbal communication. Ten year survival rates as high as 80% have been reported. Even limited physical recovery can improve quality of life and enable patients to return to live with their families. Early referral to a specialist rehabilitation service for specialist care and technology is therefore important.

Sources and selection criteria

We gathered information for this article through searches in Medline and Taylor and Francis Health Sciences, identifying relevant case series reviews on the locked-in syndrome and other brain stem strokes. Our own experience is also incorporated.

Clinical features

Locked-in syndrome was first defined in 1966 as quadriplegia, lower cranial nerve paralysis, and mutism with preservation of consciousness, vertical gaze, and upper eyelid movement.1 It was redefined in 1986 as quadriplegia and anarthria with preservation of consciousness.2 This redefinition served to clarify that mutism could imply unwillingness to speak.3

Although patients are conscious, attention, executive function, intellectual ability, perception, and visual and verbal memory can be affected.4 Leon-Carrion and colleagues reviewed 44 patients with the locked-in syndrome, of whom eight reported memory problems and six attentional deficits.5 Memory difficulties were more likely when the aetiology was traumatic.5 However, in a report of two patients with chronic locked-in syndrome, neuropsychological assessment showed preserved cognitive abilities.6

A review by Zeman of consciousness indicated that cerebral metabolism, as monitored by positron emission tomography, is only mildly reduced in locked-in syndrome but severely reduced in the vegetative state.7 The electroencephalogram typically shows slow wave activity in the vegetative state but normal activity in locked-in syndrome.

Anarthria is due to bilateral facio-glosso-pharyngo-laryngeal paralysis,8 which …

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