What is carpal tunnel syndrome?
Carpal tunnel syndrome (CTS) is a common condition that now affects 10 per cent of the UK workforce. It is caused by compression of the median nerve, which runs through a U-shaped 'tunnel': the floor and sides of this tunnel are made up of the wrist bones, with the transverse carpal ligament forming a tight 'roof'. Nine flexor tendons, running from the muscles to the bones, also occupy this tight tunnel space.
The onset of the condition is often marked by tenosynovitis (swelling and thickening of the tenosynovium, the tissue sheath surrounding the tendons), which increases pressure on the carpal tunnel, causing the median nerve and tendons to become trapped within. Ultimately, this causes numbness, tingling, nerve pain, and restricted movement of the hand and wrist. The nerve pain may also radiate up the arm to the shoulder and, sometimes, into the neck.
Eventually, compression - which restricts the supply of oxygen and nutrients - may lead to demyelinisation of the nerve, where its protective sheath is stripped away, so that it can longer carry out its job of transmitting nerve signals. Without these signals, the hand is unable to function properly and the muscles may waste away.
Although, in mild cases, the hands feel numb or tingling, in severe cases, the damage to the nerve and surrounding tissues may lead to permanently disabled hands.
The usual medical solutions
Your doctor's first port of call is usually non-steroidal anti-inflammatory painkillers like ibuprofen, or even steroid injections next to the carpal tunnel. If these don't work, the usual medical solution is surgery, which involves cutting the ligament over the tunnel to relieve the compression. This can be carried out through open surgery or with an endoscope. In the latter operation, only tiny incisions are made to allow insertion of a tiny flexible optical tube, or 'scope', which projects a magnified image on a TV screen to guide the surgeon.
The aim of both operations is to increase the carpal tunnel arch space by cutting the ligament and hoping it will grow back wider as a result of scar-tissue growth over the incision.
What doctors don't tell you
Such simplistic solutions ignore the fact that the problem underlying CTS may be complex and varied, including:
* bad posture, leading to uneven loads on joints, and overloading muscles and tendons, thus inhibiting blood flow and nerve signals
* repetitive strain injury as a result of overuse of the hand and wrist
* neuropathological conditions such as diabetes, alcoholism and polyneuritis
* inflammatory autoimmune disorders, such as rheumatoid arthritis, polymyalgia and lupus erythematosus
* altered hormonal balance as a result of pregnancy
* kidney failure, hypo/hyperthyroidism and reproductive factors that can increase fluid swelling (oedema)
* anatomical variations in the ligaments and bones
* thoracic outlet syndrome, in which there is compression of the nerves and blood vessels that supply the arms and neck (eMed J, 2002; February) (see box, p 11)
* congestion of the lymphatic vessels and veins (J Neurol Neurosurg Psychiatr, 1976; 39: 615).
Although surgery may relieve the pressure on the main nerve, by itself, it is unlikely to facilitate full recovery of the tissues. Indeed, in a study of around 700 Canadian workers (75 per cent of whom had undergone surgery), it was revealed that, four years after treatment, only 14 per cent were still symptom-free. Of the remaining patients, 46 per cent suffered moderate-to-severe pain, 47 per cent had moderate-to-severe numbness, and 40 per cent had difficulty using and grasping objects (J Hand Surg [Am], 2004; 29: 307-17).
Although doctors claim recovery times of 18-36 days, this doesn't allow for recovery of degenerating tissues that are underlying the symptoms of CTS. Surgery may relieve the symptoms temporarily, but can actually worsen the underlying condition if the patient returns to the activity that contributed to the CTS before tissues are properly healed.
Besides often failing to work, surgery is hardly risk-free. The many complications include scar sensitivity, pillar pain (temporary tenderness on each side of the palm, where the ligament is attached to the bones), recurrent symptoms and grip weakness (Clin Biomech [Bristol, Avon], 2003; 18: 685-93).
In one study of postoperative complications, of 708 people who had undergone the endoscopic surgery for CTS, 64 per cent experienced major complications, including lacerations of the ulnar, median and digital (finger) nerves as well as damage to the tendons and vessels.
Open surgery fared only slightly better. Of 616 who'd undergone this type of operation, 46 per cent suffered major complications. Researchers concluded that 'carpal tunnel release, be it endoscopic or open, is not a safe and simple procedure. Major, if not devastating, complications can and do occur' (J Hand Surg [Am], 2000; 25: 85).
People with small wrists should be particularly wary of endoscopic surgery as, in such cases, access to the carpal tunnel becomes more difficult and may result in further complications (J Hand Surg [Br], 1999; 24: 6-8).