Carpal Tunnel Syndrome

Carpal tunnel syndrome is a condition that may occur when the median nerve, a major provider of sensation to volar radial side of your hand and fingers, becomes compressed within the carpal tunnel.

The floor of carpal tunnel is formed by the eight wrist (carpal) bone and the top is transverse carpal ligament. The tunnel acts as a passageway at your wrist through which the median nerve and nine tendons (thumb and four fingers) pass to reach your hand.

Compression of the median nerve, which occurs due to a decrease in the space inside the tunnel, may be caused by conditions such as swelling of the tissue lining the tunnel (flexor tenosynovitis), fluid retention (pregnancy, thyroid disease etc.), presence of ganglion cyst, an abnormal muscle structure (proximal lumbrical origin, anomalous flexor pollicis longus slip etc.) or other conditions. In many instances, the cause is unknown (40%).

Symptoms of Carpal Tunnel Syndrome

You may feel as though your hand is “going to sleep.” Usually, your index and middle fingers are most affected, but the sensation may occur throughout your hand.

If the symptoms began recently, you may be awakened from sleep with numbness, tingling or pain, which may be relieved when you shake or rub your hand. In later stages, the numbness may become continuous.

You may also feel weakness of thumb and worse when you try to do repetitive work or try to open the jar or can.

Structure of the Carpal Tunnel

Diagnosing Carpal Tunnel Syndrome

Patient history—pain, paresthesia, numbness and tingling over distribution of median nerve, thumb, index finger, middle and ring finger.

Symptoms are often worse at night (nocturnal awakening) and are aggravated by activities that requires a fixed position of the wrist such as holding a telephone or hairbrush, typing, driving a car.

Without appropriate treatment, patients with more advanced CTS complained of difficulty of opening jars or manipulating shirt buttons. Patients with basal joint arthritis also complained of difficulty of opening jars which required differential diagnosis.

Physical examination—Although sensory complaints are the hallmark of CTS, patients with milder neuropathy frequently do not have any objective abnormalities on examination.

The sensory examination may include both threshold tests (Semmes-Weinstein monofilament and vibrometry) and innervations density tests (static and moving two-point discrimination), with the former more sensitive than the latter.

Other specific provocative tests that frequently used by clinician in diagnosing CTS including the Tinel test, Phalen test, and Durkan test. Motor deficit occurred after significant sensory impairment.

The most commonly affected and sensitive motor finding is weakness of APB muscle, innervated purely by median nerve, occurred in more chronic disease. Thenar muscle atrophy is a relatively rare and may be present with more severe or end-stage of neuropathy.

Your physician will perform a physical examination to evaluate the possibility of carpal tunnel syndrome and to rule out other probable causes of median nerve compression due to thoracic outlet syndrome (TOC) or pronator teres syndrome (Double Crush Syndrome).

Electrodiagnostic testing—This is commonly performed in the evaluation of CTS include both the nerve conduction velocity (NCV) and electromyography (EMG). The distal motor latency more than 4.5 msec or more than 1 msec compared to opposite side are abnormal.

The distal sensory latency (index finger to wrist) more than 3.5 msec or o.5 msec more compared to the opposite side. The sensitivities of NCV on diagnosis of CTS are around 49% and 84% with specificities of 95% and 99%.

EMG of thenar muscle may reveal recruitment pattern, fibrillation, and positive sharp waves in severe median nerve dysfunction. Nerve conduction studies and electromyography (NCV/EMG) may be used to confirm the diagnosis and evaluate the severity of your condition.

Imaging—Plain radiograph may sometimes obtain during the work-up of patients with CTS. Ultrasound and MRI can be used to accurately determine the dimensions of the carpal tunnel and the space available for the median nerve.

However, the diagnosis of CTS remains predominantly a clinical diagnosis and adjunctive imaging studies are rarely necessary.

Treating Carpal Tunnel Syndrome

In most cases, your treatment will begin with nonsurgical approaches that may relieve your symptoms. Many patients get relief from simply modifying their activities to reduce pressure within the carpal tunnel and wearing a wristlet only at night to keep their wrist in a neutral position, not in functional position, because functional position of wrist is 30 degrees dorsiflexion.

A steroid injection may also be used to relieve symptoms (overall recurrence rate: 8-94%). Taking medications by mouth, such as vitamin B6 or nonsteroidal anti-inflammatory drug (NSAID) may be tried for some patients to relieve symptoms due to synovitis or arthritis.

If the nonsurgical methods are unsuccessful, surgery may be recommended. The goals of surgery are to reduce pressure within the carpal tunnel to alleviate median nerve compression by release transverse carpal ligament (TCL), or flexor synovectomy, or combined both methods.

The surgeries can be open, mini-open (incision about 2 cm) or endoscopic method. Endoscopic release of carpal tunnel carries the risk of cutting of the median nerve, which is a devastating complication.

Anesthesia types include General Anesthesia, Regional Nerve Block with or without IV Sedation, IV Regional Block (Bier Block) and WALANT (Wide Awake Local Anesthesia No Tourniquet).

I prefer mini-incision carpal tunnel release to avoid long incision and complications caused by endoscope surgery.

I use Regional Block and IV Sedation with tourniquet. So, I can see truly clear all the important structures of carpal tunnel region and perform successful and thorough carpal tunnel release and flexor tendon synovectomy, if necessary, for my patients. Outcomes are particularly good.

Postoperative Care —-After carpal tunnel release, we will put on short arm splint for 2 weeks to allow complete rest of wrist joint and avoid incidental injury of wrist region and nerve. Because, after release, the median nerve function comes back.

The wrist region will be hypersensitive to touch or injury. Complete protection with wrist splint is the best policy. You must do range of motion (ROM) of the fingers of surgical hand to prevent finger stiffness.

Come back to our office after 2 weeks for removal of stitches and put on steri-strip. The skin edge may be uneven due to thick palmar skin of hand. Continue wrist brace for 4 weeks during work or at night (up to your convenience or feel).

Median nerve recovery takes about 8 weeks to 6 months to recover. During this period, you may experience some burning sensation over incision wound region, numbness and tingling and weakness of hand. But the symptoms will improve gradually.

You will be off work or one hand duty for 2 weeks. (Some patients recovered more quickly, then can go back to work earlier or even next day with splint protection, just like one of my PA which I operated.)

Then light duty of surgical hand less than 5 lbs for one month. Full activity with no restriction 6 to 8 weeks after surgery.

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