Lately my arms and hands “fall asleep” (lose circulation) while I’m in bed sleeping. Why does that happen? And is it something I should be worried about?
One would ideally think of sleeping as a time of total calm, peace and restfulness. Yet, as we all know too well, it is not always so. Many ailments make themselves known or become worse during sleep. For example, migraine and cluster headaches characteristically start or become worse during the night, and TMJ syndrome (pain from the jaw joints) results from unconscious clenching or grinding of the teeth while sleeping. Then, of course, there are sleeping problems such as insomnia, recurrent nightmares and the potentially serious sleep apnea syndrome.
Hands that fall asleep in the middle of the night suggest the possibility of carpal tunnel syndrome. Typically, patients with carpal tunnel syndrome (let’s call it “CTS”) complain of a prickly pins-and-needles sensation in the hands that are often significant enough to awaken them from sleep. Patients soon find that shaking the hands for a moment or two may alleviate the symptoms. Another interesting and also characteristic time for experiencing the symptoms of CTS is while driving. There is something about the position of the wrist while grasping the steering wheel for prolonged periods of time that triggers the symptoms. The uncomfortable sensations may be intermittent at first, but in more severe cases they become continuous and more painful. Whereas at first the symptoms may have occurred only at night or while driving, later they may persist throughout the day.
What is the cause of CTS? The problem is in the wrist, where there is an elliptical tunnel, the carpal tunnel, formed by the wrist bones on one side and a fibrous band on the other. If you look at the palm of your hand and then shift your gaze to the wrist you will notice several “cords” leading from the forearm into the hand. These are tendons that pass through the carpal tunnel. The fibrous band just mentioned lies beneath the skin but over the tendons. In addition to tendons, there are also blood vessels and nerves in the tunnel. The key nerve, the one that causes the symptoms of CTS, is the median nerve. After passing through the carpal tunnel, the median nerve goes into the thumb, index and middle fingers, as well as part of the ring finger. The median nerve is used for sensation (such as touch and temperature) as well as for muscle strength. Therefore, damage to the median nerve results in pain, loss of sensation and weakness in these particular fingers.
However, while these symptoms make CTS easily recognizable, it doesn’t always work that way. Sometimes, for unclear reasons, the whole hand may be affected, and sometimes the pain radiates up into the forearm and above the elbow. In any case, compression or pressure on the median nerve as it passes through the carpal tunnel is the cause of carpal tunnel syndrome.
Many diseases or conditions can injure the median nerve, usually by causing sustained pressure on the nerve. These include diabetes, hypothyroidism, pregnancy, and arthritic diseases such as gout, pseudogout, rheumatoid arthritis and lupus. Trauma to the wrist may also trigger the problem, but surprisingly, in over 40 percent of cases, no specific cause can be found.
You may have read or heard about carpal tunnel syndrome caused by repetitive movements of the fingers or hands. This is a hot topic among employers who have to deal with workmen’s compensation claims. Certainly there are cases where repetitive motion causes CTS, but the studies that try to link working activities with CTS are surprisingly mixed. One must therefore try to determine in any given case whether a patient’s symptoms are truly job-related, or just a coincidence.
In mild cases, CTS causes intermittent prickly sensations and numbness. In more advanced cases, as the nerve becomes more damaged, the uncomfortable sensations become constant and increasingly painful. Weakness of the muscles in the fingers and hands may develop and if not caught and treated early, there may be permanent loss of strength and function with unyielding numbness and persistent pain.
The usual recommendation for CTS patients who perform repetitive motions of the hand or heavy repetitive gripping motions is rest and avoidance of those activities for a period of time. Often a course of anti-inflammatory medications, gentle range-of-motion exercises and nighttime use of a wrist splint are helpful. More severe cases may benefit from an injection of cortisone into the carpal tunnel, and there are reports indicating ultrasound treatments may be of use as well. Persistent cases, especially when there is muscle weakness, may be treated surgically in an operation that relieves the pressure on the median nerve. An objective assessment of nerve function, usually done by EMG, which measures nerve conduction, may be desirable before surgery is undertaken in order to confirm the diagnosis. While surgery should not be entered into lightly, it is also unwise to wait until nerve injury, pain and weakness are severe since it may be too late at that point to recover function, and long-term disability results.
It sounds as though your symptoms may be mild, but I would recommend you mention them to your doctor. Hopefully, he or she will be able to relieve the symptoms and ensure that there are not other problems involving the nerves or circulation that need to be addressed.
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