By Colin Michie and Ayad Al-Moslih.
Repetitive activities, part of our busy lives, can damage nerves. The median nerve is often harmed causing carpal tunnel syndrome.
Shortly after her birthday, a niece of mine became addicted to a gaming app on her new iPhone. She played with crazy enthusiasm for several days, with few breaks and little rest. She resisted all temptations to join any family festivities. After a week, she began to complain of pain in her hands that prevented her sleeping. She developed tingling, too, that prevented her holding the iPhone, or doing up buttons. She had developed carpal tunnel syndrome. Fortunately, she recovered, but it took over a month’s separation from her beloved, new iPhone for the symptoms to disappear.
We use our hands in wonderfully sophisticated and diverse ways. Watch musicians, a painter, friends gesturing and dancing. These movements are controlled by muscles, mostly in the forearms, that operate gracefully and non-verbally through tendons. Nine tendons travel through the carpal tunnel, underneath a tough fibrous roof on the palmar side of the wrist. They are accompanied by the large and busy median nerve. The median nerve controls your dressing, sewing, keypads and gripping. It allows you to feel heat, pain or softness on your palm or index finger. Modern humans have developed many skills based around wrist and thumb functions that distinguish us from other primates. All use this nerve.
The median nerve contains thousands of bundles of individual nerve cell fibres, a profuse network conducting electrical impulses at about 50 meters a second. These need oxygen and nutrients for energy – a good blood supply. Inside those fibres, metabolically active molecules for growth and repair move more slowly. Damaged or neuropathic nerves malfunction by sending confusing or altered electrical signals to the brain, such as painful stabbing sensations. Muscles they supply become smaller and weaker, too, because they depend on the electrical activity of an intact nerve supply.
As it runs through that narrow wrist tunnel, the median nerve may get squeezed. This often starts after repetitive movements such as typing, counting money, using a wheelchair, playing an instrument, moving materials in factories. Adolescent median nerves can be put under considerable stress by texting. Vibrating tools can be a problem for some. The syndrome is more common in women in both hands and in specific situations including pregnancy, diabetes, thyroid problems, obesity and arthritis.
Nerve compression in the wrist usually starts with tingling, pain, sometimes a loss of sensation in some fingers or loss of strength in the thumb. All of these will be worse at night. In those with milder problems, such as during pregnancy, the syndrome will often resolve without specific treatment. If you are concerned, a medical review is helpful; because other problems related to nerves closer to the spine can start in a similar way. More severe symptoms are likely to need specific treatments. The use of ultrasound to look for swelling of the median nerve in the tunnel, or finding slower electrical impulses help clinch this diagnosis.
Other nerves in the arm can be damaged, although less frequently. The ulnar nerve may be stretched or squeezed at the elbow, leading to pain in the forearm and the little finger. This cubital syndrome is more common in men, and in the left hand.
To heal irritated or inflamed nerves, the cause of their problems must be removed. Adjustment of your rituals or habits, typing position or other ergonomic changes are first steps. To treat carpal tunnel syndrome, wrist splints at night assist. Analgesics are useful; hand and wrist exercises may improve symptoms for a small number of folk. Steroids taken by mouth, or injected into the wrist; acupuncture and laser acupuncture are used by some therapists, as they are often effective. Treatments usually take several weeks to work, as troubled nerves rarely heal rapidly.
Surgery can be useful if there is a persistent loss of sensation or muscle weakness in the hands. The aim of surgery is to divide the fibrous roof of the carpal tunnel to reduce the pressure on the median nerve. The procedure nowadays takes approximately 10 minutes when performed under local anaesthetic. Either a small incision (2-4 cm), or an endoscope, or perhaps an endoscope with fluid, can used to help increase the size of the tunnel. Symptoms can persist or recur in a small number of sufferers: revision surgery may be necessary.
Go gently and use both hands carefully, in moderation. The nerves in your arms are not as tough as you might think. You need to preserve your dextrous skills, awareness and intelligence that rests in your hands.
Useful resources:
https://www.nhs.uk/conditions/carpal-tunnel-syndrome/
https://www.csp.org.uk/public-patient/rehabilitation-exercises/carpal-tunnel-syndrome
https://www.webmd.com/pain-management/carpal-tunnel/how-can-i-prevent-carpal-tunnel-syndrome
