Locked-In Syndrome

Locked-in syndrome (LIS) is a diagnosis which encapsulates patients who are alerts, cognitively conscious and capable of communication but are unable to move or speak (American Congress of Rehabilitation Medicine, 1995). LIS is most often the result of a ventral pons lesion characterized by motor de-efferentation producing paralysis of all four limbs (American Congress of Rehabilitation Medicine, 1995; Smith and Delargy, 2005). There are difference subcategories, described below, that breakdown the extent of motor and verbal impairment, which can be complete or partial (American Congress of Rehabilitation Medicine, 1995).

Original Editor - Your name will be added here if you created the original content for this page.

Lead Editors  

Clinically Relevant Anatomy

add text here relating to clinically relevant anatomy of the condition

Epidemiology

The precise prevalence rate of LIS is not specifically documented in the literature and the incidence rate is thought to be underestimated. However, the population of patients with LIS as discussed in the literature is found to have relatively equal frequency amongst men and women and occurs most frequently between the ages of 41-52 years (Leon-Carrion et al, 2002). Furthermore, 60% of cases LIS is caused by a basilar artery occlusion or pontine hemorrhage, but it can also be caused by traumatic brain injury (TBI) (Schnakers et al., 2008; casanova, 2003).

Mechanism of Injury / Pathological Process

The most common etiology of LIS it due to ventral pontine strokes, although more than 20 different mechanisms of LIS have been described (Doble, Haig, Anderson, and Katz, 2003). Most commonly ventral pontine infarction is the result of basilar artery occlusion. (Casanova et al., 2003). Less frequent causes of LIS include tumours, infection, trauma, lesions, and hypotensive events in other areas of the brainstem (Doble, Haig, Anderson, and Katz, 2003).

Clinical Presentation

add text here relating to the clinical presentation of the condition

Diagnostic Procedures

The neurobehavioral criteria for diagnosing LIS consist of:

1. Maintained eye opening
2. Basic cognitive abilities are preserved
3. Severe hyophonia or aphonia
4. Quadriparesis or quadriplegia
5. Communication through vertical or lateral eye-movement or blinking (American Congress of Rehabilitation Medicine, 1995).
   
   

Outcome Measures

add links to outcome measures here (see Outcome Measures Database)

Management / Interventions

add text here relating to management approaches to the condition

Differential Diagnosis

LIS can present in a similar clinical manner to various other conditions and therefore should be thought of while assessing a patient, in order to provide a correct diagnosis (Laureys, 2010). Potential alternate disorders or conditions that present in a similar clinical manner to LIS include Guillain-Barre syndrome, myasthenia gravis, poliomyelitis, polyneuritis, or bilateral brainstem tumours (Laureys, 2010).Furthermore, LIS could be mistaken as Akinetic mutism, which is a rare neurological condition where the individual will not move (akinetic) or talk (mute) despite being awake (Laureys, 2010).

Finally, LIS diagnosis can be missed and mistaken as being in a vegetative state (Laureys, 2010). This is even more common in those with vision or hearing problems, which makes the LIS diagnosis even more difficult (Laureys, 2010).

Key Evidence

add text here relating to key evidence with regards to any of the above headings

Resources

add appropriate resources here

Case Studies

add links to case studies here (case studies should be added on new pages using the case study template)

References

References will automatically be added here, see adding references tutorial.