Locked-in syndrome

Definition

Locked-in syndrome is a condition in which an individual is fully conscious, but all the voluntary muscles of the body are completely paralyzed, with the exception of the muscles controlling eye movement.

Description

Locked-in syndrome is a catastrophic condition that prevents an individual from voluntarily moving any muscles of the body, other than those that control eye movement. As a result, the individual cannot move or speak, although some communication is possible through blinking or eye movements. Despite the devastating loss of function, an individual with locked-in syndrome is completely conscious and aware, able to think and reason normally. Luckily, locked-in syndrome is exceedingly rare.

About 40–70% of people suffering from locked-in syndrome die within a short time of suffering the causative injury.

Causes and symptoms

Locked-in syndrome can occur after severe, catastrophic brain injuries due to massive stroke , traumatic head injury, or ruptured aneurysm. Diseases that destroy the myelin sheath around nerves and the toxic effects of medication overdose can also cause locked-in syndrome. The most common cause involves any condition that affects an area of the brain called the ventral pons; all of the nerve tracts responsible for voluntary movement pass through the ventral pons. Areas of the brain responsible for cognition and consciousness are above the level of the ventral pons, and are therefore preserved.

Symptoms include complete inability to control any voluntary muscles in the body, other than those for eye movements and blinking. Reasoning, thinking, consciousness, and awareness are preserved. Normal sleep and wake cycles persist throughout the locked-in state.

Diagnosis

Diagnosis is evident in a conscious individual with no muscle functioning, save for the ability to respond to questions by blinking a certain number of times per the interviewer's directions. Further diagnostic tests will be required to determine the underlying cause of the condition; CT or MRI scans can reveal the presence of an aneurysm or stroke.

Treatment team

Patients with locked-in syndrome are cared for by critical care specialists, neurologists, and physiatrists. A variety of therapists may also work with such patients, including physical therapists, occupational therapists, speech and language therapists, and psychotherapists.

Treatment

There is no cure for locked-in syndrome. Treatment is supportive.

Recovery and rehabilitation

One of the most important goals of rehabilitation involves finding assistive devices that can help with communication. A technique of stimulating muscle groups with electrodes (called functional neuromuscular stimulation) sometimes can help restore some small degree of functioning; however, even being able to move one finger can greatly improve an individual's ability to communicate or operate assistive devices that could improve that person's level of functioning.

Prognosis

Locked-in syndrome has a very poor prognosis, although some individuals have lived as long as 18 years with the condition.

Special concerns

Ethical dilemmas regarding the treatment and wishes of patients with locked-in syndrome are complicated.

Resources

BOOKS

Hammerstad, John P. "Strength and Reflexes." In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003.

Simon, Roger P. "Coma and Arousals of Disorder." In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000.

PERIODICALS

Hayashi, H. "ALS patients on TPPV: totally locked-in state, neurologic findings and ethical implications." Neurology 61, no. 1 (July 2003): 135–137.

Rosalyn Carson-DeWitt, MD

locked-in syndrome (lokt-in) n. a condition resulting from damage to the brainstem, in which the patient is conscious but unable to speak or to move any part of the body, except for blinking and upward eye movements, which permit signalling. Compare persistent vegetative state.