Carpal Tunnel Syndrome

Overview

Carpal tunnel syndrome (CTS) has many different symptoms, but they all result from the pain and discomfort of a pinched nerve in the wrist. The median nerve, along with nine flexor tendons, passes from the forearm into the hand through a space called the carpal tunnel. This tunnel is formed in the space between the transverse carpal ligament on the palm side of the wrist and small wrist bones on the other side (Figure 2). When swelling occurs in this tunnel, pressure on the nerve results in varying degrees of discomfort, numbness, or pain, and when severe, it can result in permanent damage (Figure 1).

Causes

Swelling in the carpal tunnel can have many varied causes, and in many cases, the ultimate cause may remain unknown. Injuries such as joint dislocations or fractures can cause swelling, but so can simply keeping the wrist bent in one position for long periods of time. Symptoms of CTS can also be caused by other medical conditions that cause the lining of the flexor tendons to swell, arthritis, thyroid conditions, diabetes, and fluid retention during pregnancy (which usually abates after delivery). Basically, anything that creates swelling in the carpal tunnel can be a cause of CTS because it is the swelling inside the tunnel that pinches the median nerve.

Symptoms

Usually, the symptoms of CTS are observed during the night, but they may also appear during normal everyday activities like driving or holding a book. Pain is a common symptom, but numbness or tingling may also occur, usually in the thumb, index, middle, and ring fingers (Figure 1). Sometimes symptoms involve a change in performance: a loss of grip strength, occasional clumsiness, or an increase in dropping objects. When cases are extreme, permanent loss of sensation or strength may result.

Diagnosis

Diagnosing CTS is possible from a detailed history and physical exam. An x-ray can help detect injuries, fractures, or arthritis as alternative causes of symptoms. Laboratory tests can help confirm this, or other problems, but the results may not correlate with the degree of symptoms. For instance, electrodiagnostic tests like nerve conduction velocities (NCV) and electromyograms (EMG) can check for these related conditions and help confirm median nerve slowing at the wrist.

Non-Invasive Treatments

Treatment of CTS symptoms can vary widely depending on the severity. Some of the least invasive treatments include altering habits in the use and positioning of the hand to lessen the pressure on the nerve. Wearing a splint to keep the wrist in a straight position can also minimize this pressure (Figure 3), and wearing it at night can reduce some of the symptoms that interrupt sleep. If these treatments are ineffective, a steroid injection into the carpal tunnel can lessen the swelling around the median nerve.

Surgery

More severe cases, or cases in which there is no improvement, may require surgery. By cutting the ligament that covers the tunnel’s palmar side, surgeons can relieve pressure around the nerve. The incisions may vary for this surgery, but the goal is always to make the tunnel larger, increasing space and decreasing pressure around the median nerve (Figure 2 – AFTER Surgery). Recovery also varies in time and effectiveness. In extreme situations, CTS symptoms may never be completely alleviated. In other cases, the numbness and tingling can disappear rapidly or gradually fade over several weeks or even months; soreness around the incision may also vary in the length of time required to go away. Several months may also be needed for strength and use in the wrist and hand to return to normal.

In the typical post-op CTR patient with moderate severity CTS, only a day or two of pain medicine is needed after this outpatient procedure. The wrist splint is used for support for 2-3 weeks, light use of the hand is permitted immediately (i.e. eating, dressing, simple grasping), and most of the numbness is gone in a few days or weeks. Full grip strength and tolerating hard pressure on the incision usually take 6-8 weeks.  Sleeping better and the relief of any referred pain into the elbow or shoulder are immediate, though.

At Trinity Hand Specialists, healthy patients may opt to have this procedure in the office, wide awake, and with local anesthesia only; otherwise, it can be scheduled as same-day surgery with intravenous sedation at one of the area ambulatory surgery centers.

CTS pattern of finger numbness and tingling
Figure 1
Numbness and tingling may be in any or all of the 3 1/2 fingers shown and is an earlier symptom. Loss of thumb muscle strength is a late symptom in chronic CTS cases.
Diagram of carpal tunnel anatomy both BEFORE and AFTER surgery
Figure 2
With surgery, the average tunnel size increases 20% from the size of a flattened dime to that of a nickle. The ligament then heals in this more open position with a seam weld of scar tissue.
Recommended Carpal Tunnel splint
Figure 3
This type of wrist control splint for sleeping should be sized specifically for the left or right wrist - not one that’s made for both. It should reach the mid-forearm as shown and not be much shorter than this for best comfort. The splint helps keep the wrist straight which gives the nerve the most room in the carpal tunnel.