Carpal tunnel syndrome (CTS) is caused by the compression of the median nerve in the carpal tunnel. The carpal tunnel is formed by the carpal bones below and the flexor retinaculum (transverse carpal ligament) above (the “roof”). The contents of the carpal tunnel include finger flexor tendons and the median nerve.
CTS can result from any mechanism which compresses the median nerve – inflammation or tumor. Diabetes, hypothyroidism and pregnancy may also be associated with carpal tunnel problems.
Typically, however microtrauma from repetitive finger or wrist flexion movements is the causative factor. Occupations prone to CTS are factory work and typing.
Symptoms include: numbness, tingling, pain, and weakness in the hand especially toward the thumb or index finger. In severe cases, the thumb muscles become weak and decrease in size. Often, people will report waking at night needing to “shake their hands out” to relieve numbness.
Besides the history, special tests in the focused physical exam include:
Phalen’s test (most helpful): the patient places the dorsum aspects of each hand together with the wrists flexed and brings the hands to the chest. Hold for 30-60 seconds asking for subjective complaints of numbness, tingling or pain.
Manual compression of the median nerve: place thumb on the median volar wrist crease and press firmly holding from 10-20 seconds. Positive sign is symptom reproduction.
Diagnosis is made from history and physical. Occasionally a nerve conduction velocity or EMG test is performed to judge extent of nerve damage.
Treatment of carpal tunnel syndrome includes
Ice packs 10-15 minutes for acute inflammation
Bracing: Should contain a metal stay used maintain the wrist in 30 degrees of extension -to be worn at night while sleeping and during activities of daily living or work which aggravate or contribute to the CTS symptoms (e.g. typing)
Nerve gliding1: Use heating pad on the wrist for 15-20 minutes then make a fist, extend fingers, extend wrist, supinate forearm, extend thumb. Repeat 5-10 times.
Wrist extension strengthening: Rest the forearm on the
Extend the wrist upwards.
thigh (or a flat surface) with the hand beyond the edge of the surface, palm down, holding a light weight (1-3 lbs). Extend the wrist (against gravity) 10 times. Continue sets of 10 until the forearm muscles fatigue.
Mechanical traction 2: a relatively recent showed that a mechanical carpal ligament traction unit was effective at relieving a substantial amount of numbness, tingling, and pain due to median nerve entrapment after four weeks of therapy.
With conservative management, expect 4-6 weeks for improvement. If no improvement or if symptoms worsen, consult surgeon for consideration of a carpal tunnel release.
In determining risk versus benefit of surgery, up to 20% of patients report recurrent symptoms. Most failures are due to incomplete release of the transverse carpal ligament.
Resolution of symptoms is to expected from 6 weeks to 6 months. 3
Return to work and activities of daily living is dependent on restoration of full range of motion and strength. Strength testing includes objective grip and finger pinch strength testing via dynamometer. Pain levels should be monitor but not be used as the sole basis for return to work.
Essential of Musculoskeltal Care 3 rd Edition, American Academy of Orthopedic Surgeons, pg 325.
New carpal ligament traction device for the treatment of carpal tunnel syndrome unresponsive to conservative therapy. Porrata H. et al., Journal Hand Ther 2007 Jan-Mar;20(1):20-7; quiz 28.