We describe about carpal tunnel syndrome, tests, wrist brace and carpal tunnel release surgery.
Carpal tunnel syndrome
In carpal tunnel syndrome, median nerve gets pinched in the carpal tunnel at the wrist, which leads to numbness and tingling and pain affecting the thumb index and middle fingers of the hand along with, if it is of severe degree, weakness of the thenar muscle group of the hand and thus affecting the thumb and next 2 fingers muscles and tendons strength.
The patient suffering from this condition complains about having numbness and tingling involving the hand fingers which gets worse during repetitive flexion and extension movements of the wrist like typing, holding on the steering wheel during driving, gardening, carrying things with the hands and participating in activities which require repetitive hand motions. Patient also complains about waking up during the middle of night with burning and stinging, tingling sensation in the hand going upwards and thus requiring repetitive shaking of the hand to get some relief. If the thenar muscle group becomes wasted then patient has difficulty in opening jars, opening car door with the keys etc.
Carpal tunnel syndrome tests
On clinical examination, percussing with a finger at the wrist elicits numbness and tingling going down the thumb, index and middle fingers which is similar to the symptoms which patient usually experiences, it is known as Tinel’s sign.
Flexing the hand at the wrist for a minute or so elicits the same above described symptoms and is known as Phelan sign.
Nerve conduction studies and EMG ( Electromyography)
is the definite test for the diagnoses of carpal tunnel syndrome, it not only makes a definite diagnosis of carpal tunnel syndrome but also gives information regarding the severity of the carpal tunnel syndrome and also exclude other causes which can mimic the symptoms of carpal tunnel syndrome. Other conditions which can mimic the symptoms of this condition are cervical radiculopathy, thoracic outlet syndrome, ulnar neuropathy or proximal entrapment of the median nerve in between 2 heads of pronator teres in the proximal portion of the forearm rather than at the carpal tunnel.
Technique of the NCS and EMG test
During the nerve conduction studies of the arm, median nerve is tested by placing bipolar recording electrodes at the wrist and stimulating the median nerve sensory fibers first at the palm and then at the index and middle fingers and thus latencies of the sensory fibers from the stimulating site to the recording site can be measured and amplitudes of such responses are also recorded. In the next step, disc recording electrodes are placed at the abductor pollicis brevis muscle over the thenar eminence and at the base of the thumb and median motor nerve is stimulated at 6.5 cm proximally from the recording electrode and thus median nerve distal motor latency and amplitude of the compound muscle action potential( CMAP) is measured.
In the case of carpal tunnel syndrome, median nerve distal sensory and motor latencies are prolonged and amplitudes of the sensory fibers and motor fibers are decreased and thus a diagnosis of carpal tunnel syndrome can be made.
Next, ulnar nerve sensory and motor fibers are similarly tested by stimulating and recording over the ulnar nerve which is next to the median nerve on the medial side of the forearm and hand. This gives information regarding the integrity of the ulnar nerve which in case of compression can cause numbness and tingling in the hand but it is in the medial 2 fingers of the hand rather than thumb, index and middle fingers. Sometimes, superficial radial nerve is also tested on the dorsum of the thumb to complete the nerve conduction studies. If all the nerves show slowing and low amplitudes then it is usually due to diffuse disease process like peripheral neuropathy.
In the second portion of this test, a tiny Teflon-coated needle is inserted in different muscles of the arm and electrical activity is recorded, this test is very important in ruling out the possibility of pinched nerve in the neck( cervical radiculopathy) or brachial plexopathy or thoracic outlet syndrome.
Nerve conduction studies and EMG is The only test to make a definite diagnosis of carpal tunnel syndrome and exclude other causes which can mimic its symptoms. This test has been around for more than 50 years.
Carpal Tunnel Wrist Brace
Carpal tunnel Wrist brace is helpful to avoid pressure over the median nerve in the carpal tunnel by keeping the hand straight and in slightly upward position and thus it can help to alleviate the symptoms of carpal tunnel syndrome temporarily. It is especially helpful at nighttime during sleep so that the wrist does not bend to cause more pressure over the median nerve. It can be also used during work however doing so can put more strain on the tendons and lead to pain in the hand. Wearing the wrist brace for prolonged periods of time can lead to weakness of the hand muscles and is not indicated. If one has to wear the brace then after taking it off periodically along with stretching and strengthening and range of motion exercises of the hand muscles should be done regularly.
If carpal tunnel syndrome is mild in degree then wearing the wrist brace and avoiding activities which require repetitive flexion-extension movements of the wrists can alleviate the symptoms and patient may not require decompressive surgery however, that may not be possible in persons whose occupation requires such activities on a daily basis.
Carpal tunnel release surgery
For carpal tunnel release surgery, incision is made over the carpal tunnel at the wrist and transverse carpal ligament is cut which holds the tendons and median nerve inside the carpal tunnel tightly and thus pressure over the median nerve is removed . After this tight carpal tunnel ligament is cut, there is more space available inside the compartment for the nerve to move freely.
If surgery is done for mild or moderate degree of carpal tunnel syndrome then majority of the patient’s become completely asymptomatic however if the surgery is done late, symptoms might not get any better but it can prevent any further progression of the damage. Carpal tunnel release surgery is done on outpatient basis under local anesthesia and it usually takes about 2 weeks for the incision to heal up and then patient can return back to his normal activities.
Various therapies have been advocated for the treatment of carpal tunnel syndrome including physical therapy, chiropractic treatment, vitamin B12, various supplements and local corticosteroid injection, all these techniques might help temporarily if patient has mild degree of carpal tunnel syndrome otherwise all these measures ultimately prove to be of no help and patient ends up requiring decompressive surgery anyway.