Why Are My Hands Numb?

For the last three weeks I have had growing numbness in my left hand, mainly my pinky finger, and some in my ring finger. It also goes up my forearm to my elbow. Should I see a doctor about this, and if so, what should I ask?

The little finger and the outside of the fourth finger next to it are innervated through the ulnar nerve, which passes along the inside of the elbow in the notch that one can feel there. The pain and electrical sensation that we feel when we bang our “funny bone” there are caused by momentary trauma to the ulnar nerve.

There are a number of reasons why we can get a neuropathy in the ulnar nerve causing this numbness. Since the nerve is located in a very exposed position, it is easily traumatized; and repeated trauma can cause the numbness to appear more often or even become permanent. Sitting with one’s elbows on the table while reading, a position that many people like, may put pressure on the ulnar nerves in both arms. The channel at the elbow that the nerve runs through can become narrowed by a buildup of calcium.

I think one of the most common causes is sleeping with one’s head cushioned on one hand. This requires that the elbow be bent up to its maximum flexion, and the ulnar nerve gets stretched tight in the bony channel that it runs through. I have had this form of ulnar neuropathy myself for several years, and will awaken during the night with the same numbness you describe. My numbness disappears quickly if I straighten my arm, but I don’t like the feeling nonetheless, and try not to sleep in that position. If I keep my elbow bent at no more than a 90 degree angle, I don’t get it.

Sleeping positions can cause many forms of numbness, all because pressure is placed over a nerve, or the nerve is stretched. Numbness of the first three fingers of the hand, the palm and most of the forearm can be due to stretching of the median nerve in the upper arm if one sleeps with an arm up over one’s head. Certain leg positions during sleep can press on the peroneal nerve on the outside of the leg just below the knee. This will produce numbness running down the outside of the leg, and may cause weakness of the muscle that raises the foot up.

Another cause of median nerve neuropathy that I have seen is walking with the old style crutches which can press on the median nerve up in the armpit. This is a major reason why anyone who must use crutches for more than a short period of time should use the type that grip the upper arm but don’t extend up to the armpit.

Carpal tunnel syndrome is a neuropathy caused by pressure on the median nerve where it passes through the carpal tunnel at the wrist. Many cases are due to a congenital narrow tunnel, but some repetitive motions performed with the wrist either bent up or bent way down can also cause it. People with an inflammatory arthritis of the wrist may have enough swelling to cause pressure on the nerve. The numbness is of the thumb and next two fingers, plus the inside half of the fourth finger, and most of the palm.

Another neuropathy that I often get is numbness of the lower leg and outside of the foot when I have been driving for many hours. I have permanent mild numbness in these areas due to old sciatica, but when I sit without moving while driving, the pressure on my buttocks or the backs of my thighs greatly increases my numbness. This also clears up promptly when I get out of the car and walk or stretch.

I have probably told you more about neuropathies than you wanted to know, but I know that many people have these episodes of temporary numbness, and worry that they might be having a stroke, so I wanted to describe the more common ones. If numbness, such as you describe, is always associated with a particular position of your arm, and goes away promptly when you change that position, then I think you are having the type of neuropathy that I have described and probably don’t need to take it further or even see a doctor. If it doesn’t clear promptly, or if you cannot associate it with any particular position, or if weakness in the fingers of the hands occurs, then you should certainly have it evaluated. There are surgical procedures to move the ulnar nerve out of its channel at the elbow.

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