Locked-In Syndrome

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

The three categories of LIS:

1. Classic—Quadriplegia and anarthria with preserved consciousness and vertical eye movement
2. Incomplete—The same as classic but with remnants of voluntary movement other than vertical eye movement
3. Total—Total immobility and inability to communicate, with full consciousness.

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Clinically Relevant Anatomy

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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. 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).

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. Most commonly ventral pontine infarction is the result of basilar artery occlusion. Less frequent causes of LIS include tumours, infection, trauma, lesions, and hypotensive events in other areas of the brainstem.

Clinical Presentation

Early literature estimated that LIS had a mortality rate of ~60%, with mortality highest in the first six months. However, more recent studies indicate the 5-year survival rate to be greater than 80%. It has been demonstrated that patients have greater rates of survival if they are younger at the time of insult and if they received rehabilitation and nursing care early after their diagnosis. Mortality rates have been found to decrease to 14% in those patients who were able to begin their rehabilitation in the acute stage of the syndrome. Although, the majority of people with LIS remain in the locked-in stage or have serious impairments.

A retrospective study focused on the impairments present in those with locked-in syndrome and found that neurological impairments remained in all subjects and that the majority of patients had poor object manipulation and oral communication. However, functional gains were evident because many individuals were able to the decrease their use of medical devices such as feeding tubes and urinary catheters. Moreover, communication was maintained in patients through eye or facial movements, computer technology, or letter boards, where they were able to use their upper limbs to point to a respective letter. It is important to note that those with LIS will have a high burden of care and will require the support of extended care facilities or family members. Finally, those who did pass away had various complications including heart disease, multisystem failure, pneumonia, respiratory failure, internal bleeding and aspiration.

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.
   
   

Diagnosis for LIS is a long process and is often initiated when a family member or care staff report they have noticed a sign from the patient that the individual is aware. With the knowledge that LIS affects the brainstem, physicians must do neurological testing and should focus on the patient’s eye movements. A brainstem lesion is determined if the horizontal eye movement is abnormal with unilateral or bilateral conjugate gaze or with the absence of abduction of either eye.

Diagnosis of LIS is often overseen if vertical voluntary eye movement is not assessed in the unresponsive patient. Testing vertical voluntary eye movement can be achieved through having the patient voluntarily track your finger movement. If it is suspected that a patient has LIS, they must be immediately referred for neurologic and neuroradiologic consultation. A MRI must also be done to confirm a lesion in the ventral pons and at that point if not already completed, vertical eye movement should be assessed to determine if this voluntary movement is retained.

Outcome Measures

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Medical Management 

Research shows that multidisciplinary rehabilitative treatment that is introduced early, within one month of onset if possible, greatly improved the health of LIS patients and decreased the mortality rate (Casanova, Lazzari, Lotta, & Mazzucchi, 2003;. Although the specialties of each profession vary, the team has several shared goals including maintaining overall health, maximizing quality of life, practicing communication skills and improving cognition (Høyer, Normann, Sørsdal, & Strand, 2010).
Multidisciplinary care teams generally consist of:

• Physicians
• Nurses: assist with bowel and bladder function, positioning, respiratory training, administration of medication, and in just about all other aspects of care
• Speech language therapists: assist with re-learning swallowing techniques, communication strategies with eye movements or more advanced assistive devices, proper breathing techniques
• Occupational therapists: aid with the use of assistive devices, modification of ADLs, communication strategies (; Høyer et al., 2010)

Psychologists: preparing patients for their new reality and environment (Høyer et al., 2010)

Physiotherapy Management

Extensive physiotherapy is highly recommended for patients with LIS as soon as possible after diagnosis. Unfortunately, outdated beliefs that people with LIS will not improve, or frustrations as a result of slow progress means not all patients receive rehabilitation services or adequate therapy. Studies show that patients who receive early aggressive therapy and ongoing therapy (5-6 times per week) have demonstrated improved function and decreased mortality whereas the severity of LIS is exacerbated when therapy is discontinued.
LIS can present in a variety of severities, and patients may recover different functions at different rates if at all. Some recovery of function is predictable and therefore can direct the focus of physiotherapists, for example motor control tends to recover in a distal to proximal fashion, with many patients regaining some distal control of fingers and toes; Høyer et al., 2010). Other patients may be able to gain enough function to be relatively independent through use of an electric wheelchair and computer. The best course of physiotherapy therefore is an individualized therapy plan with focus on patient goals and life choices which often emphasize movements that may allow for increased communication and independence allowing for greatly improved quality of life.

Physiotherapy- early stages:

Typically, the goals of the multidisciplinary team in the immediate aftermath of diagnosis include maintaining airway and adequate oxygenation to help the patient recover. The role of physiotherapy at this stage include:

• Positioning: changing the position of the patient frequently will allow not only for increased comfort, but will assist with postural drainage, the prevention of edema, the prevention of bed sores, help to avoid aspirations of bronchial secretions, and decrease the chances of further complications associated with maintained static positioning (http://www.physio-pedia.com/Exercise_in_Critical_Care) (Casanova et al., 2003)
• Prevent complications from immobility: passive limb mobilizations are a critical part of the physiotherapist’s role in early stages to help prevent contractures and periarticular calcifications, as well as reduce the amount of spasticity that may be present.
• Cardiorespiratory physiotherapy: physiotherapists with cardiorespiratory experience play a key role in early recovery by utilizing positioning skills for postural drainage (especially the Trendelenberg position), using suctioning to clear secretions and prevent pulmonary complications, performing chest mobilizations to assist with respiration and drainage of secretions, and teaching the patient deep breathing exercises as soon as they are able .

Physiotherapy: Ongoing

• Continue limb mobilization: can progress to active assisted range of motion if patient regains some control (Casanova et al., 2003). It is also important to practice range of motion and strengthening with ocular muscles as this is important for communication in most patients with LIS
• Continue cardiorespiratory physiotherapy as neededHøyer et al., 2010;
• Treat abnormal tone and spasticity: common presentations of LIS patients include varying levels of tone and spasticity which can be treated by physiotherapists in multiple ways (link http://www.physio-pedia.com/Neurology_Treatment_Techniques)Høyer et al., 2010)
• Repetitive sensorimotor training: even in patients with near complete central paralysis of arms, repetitive training of identical movements has been shown to accelerate recovery of motor function of the arm and hand; Høyer et al., 2010).
• Increase endurance/attention span: patients often have limited capacity early on especially when learning to communicate with vertical eye movement and in physical tasks (Høyer et al., 2010;. Therapy sessions should be intense and function to gradually increase endurance and capacity for attention (Høyer et al., 2010). Weight bearing and endurance have been shown to increase through the use of wheelchairs, tilt tables and standing frames if the patient is able (Høyer et al., 2010).
• Task oriented training: using patient goals as a guide, repetitive task oriented training can help establish long-term motor patterns which may result in useful everyday functions, such as pushing a button or steering an electric wheelchair (Høyer et al., 2010).
• Muscle strengthening: limited evidence on direct muscle strengthening exists, however indirect strength gains from task-specific and sensorimotor training have been shown to increase function.
• Increase head and trunk control: due to axial hypotonia, these functions are often the last to be regained, if they can be recovered at all (Høyer et al., 2010). Training therefore should begin early and be part of most therapy sessions due to the importance of trunk and head control for active sitting and communicating in patients with LIS (Høyer et al., 2010).

For Patients with Incomplete LIS

These patients may be able to regain more motor function than patients with (complete or classic) LIS, and therefore may be able to utilize more advanced therapy (Høyer et al., 2010).

• Treadmill therapy with body weight support: Høyer et al. (2010) have shown promising results in their study using supported treadmill therapy in patients with incomplete LIS. The amount of improvement ranged dramatically from being able to practice walking highly assisted, to supporting themselves in pivot transfers, or to just regaining some control of the head and trunk, but all patients showed some improvement (Høyer et al., 2010).

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

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