Carpal Tunnel Syndrome (CTS) is caused by compression of the median nerve at  the wrist. The median nerve supplies sensation to the thumb, index and middle fingers, and controls thumb movements. As the nerve enters the hand, it passes through a tight area bounded by small wrist bones and a tough tissue band – the carpal tunnel, where repetitious wrist movements and certain medical conditions, can compress the nerve and its blood supply, causing swelling and irritation. CTS mostly afflicts both hands with the dominant hand usually more affected.

Symptoms:

• Numbness, pain and tingling of the hand –

especially at night, causing sleeplessness

• Grip weakness

• Pain radiating to the forearm or shoulder

• Sensations of swollen fingers

A good history and examination of hand sensation and strength are helpful in diagnosis. An important investigational tool is the median nerve conduction study and electromyography of the muscles supplied by the median nerve.

The median nerve carries electrical impulses enabling the hand muscle to work. If the nerve is compressed or its blood flow is compromised, the electrical impulses to the hand muscles slow down or cease. Sensations from the skin of the hand cannot be perceived well. A nerve conduction study evaluates the flow of electrical impulses through the nerve and may indicate where there is abnormal impulse slowing or a block.

Electromyography tests muscle condition. Muscles cannot contract with full force when they do not receive enough impulses from the nerve. Certain changes develop in their structure. Electromyography reveals such muscle abnormalities.

These tests also indicate if there is a generalized nerve disorder or a nerve compression in the forearm or neck. Other tests are ordered if these conditions are suspected.

Treatment involves splinting the hand to relieve pressure on the nerve and its blood supply. This is by far the most effective way to reverse symptoms and damage in the earlier stages of the disease. In addition, oral anti-inflammatory agents can reduce pain and discomfort. Sometimes, local steroid injections can help as can occupational and physical therapy. In severe cases, surgery to relieve nerve pressure is undertaken when pain and weakness do not improve with initial measures.

It is important to identify the causative factors of CTS and educate patients to change work and lifestyle habits to prevent its recurrence. If causes are identified and treated early, the outcome is very favorable, with good recovery of nerve and muscle function.

Shameela Ahmed, M.D., is a graduate of

Dow University of Health Sciences,

Karachi, Pakistan. She completed a residency in neurology from Loyola University Medical Center. Her fellowship was in clinical neurophysiology from the University of Tennessee, Memphis, with emphasis on neuromuscular diseases and electromyography. She is a board-certified neurologist and a clinical neurophysiologist.