Carpal Tunnel Syndrome, Nerve Compartment Syndrome
No, a problem with circulation is not usually the culprit when a person experiences prickling in some of their fingers, a tingling sensation or their whole hand falls asleep. The most common reason for these symptoms and pain is a constriction of the nerve path, known as carpal tunnel syndrome. If a nerve path is constricted, this causes sensory problems, pain and muscle weakness in the nerve’s area of distribution. There are numerous compartment syndromes: carpal tunnel syndrome, cubital tunnel syndrome, tarsal tunnel syndrome and others.
The index, middle finger and thumbs are typically affected. The person may first notice that their hand falls asleep at night and a burning numbness in the ball of the thumb and index finger. This is also accompanied by daytime pain and sensory disturbances that radiate into the arms. Carpal tunnel syndrome can also occur on both sides of the body (50-60%). Symptoms similar to those of carpal tunnel syndrome may also occur in cases of nerve root irritation, e.g. when there is intervertebral disc damage to cervical spine. This can be ruled out by carrying out a neurological examination.
What will the doctor want to know?
Carpal tunnel syndrome is diagnosed based on the typical description of symptoms, the neurological examination and electrical testing of the nerve conduction velocity (electroneurography). More recently, however, high-resolution sonography has made it possible to visualize the nerve path itself, thereby improving the diagnostic certainty even more.
Damage to a peripheral nerve can cause pain, impaired sense of touch, diminished strength or paresis. Carpal tunnel syndrome can start gradually with the hand falling asleep or, for example, acutely after intense exertion or during pregnancy. In this case, the constricted nerve is the median nerve (Nervus medianus).
There are usually no symptoms in the hand at first. As the condition progresses, pain radiates throughout the arm, often all the way to the shoulder and disrupting the person’s sleep. Usually, this symptom can be quickly alleviated by shaking the hands to wake them up again. The longer the pressure on the nerves persists, the more severe and longer symptoms will last. A persistent numbness of the fingers causes problems with finger dexterity: for example, it may be difficult to button up or nearly impossible to open the clasp of a necklace. The pinkie finger usually is not affected by this numbness.
Cubital tunnel syndrome is caused by a constriction of the ulnar nerve (Nervus ulnaris) in the elbow. The symptoms are numbness on outer edge of the hand and on the ring and pinkie finger as well as weakness in the finger muscles.
Tarsal tunnel syndrome is a compression of the Nervus tibialis around the medial malleolus in the foot, resulting in pain and discomfort in the forefoot and in the toes.
In most cases compartment syndromes occur without being able to identify the exact cause. Carpal tunnel syndrome is caused by a constriction of the median nerve (Nervus medianus) under a ligament (Ligamentum carpi transversum). This tunnel in the wrist narrows with age to a greater extent in women than in men until finally the nerve becomes damaged by this pressure. Risk factors for the narrowing of the tunnel are repetitive monotonous wrist movements, hormones during pregnancy, obesity, computer work, work involving vibrations, etc.
Much less common causes for carpal tunnel-like symptoms can be attributed to the family of rheumatic disorders or inflammation of the nerves (e.g. Lyme disease).
Compartment syndromes are usually very treatable. Conservative therapy with wrist braces or cortisone injections helps in less acute cases of carpal tunnel syndrome. A surgical procedure to make room for the nerve again usually alleviates the problem very quickly and is effective in the long-term.