NOTICE: Posting schedule is irregular. I hope to get back to a regular schedule as the day-job allows.

Monday, April 23, 2012

The GUIDE: Carpal Tunnel Syndrome, Redux [Full link to blog for email clients.]

It seems like every week I'm reminding readers that errors in the text of this blog may be the result of transcription from dictation software. I've been trying to deal with the consequences of severe carpal tunnel syndrome since early March. Today I went for diagnosis, and the experience left me thinking of different things that I could add to this blog in order to inform and entertain my readers.

As defined before, carpal tunnel syndrome results from inflammation of the median nerve as it passes through a groove in the wrist which accommodates muscles, nerves, and blood supply for the hand. These items have to pass over the joint capsule of the wrist so that they are not pinched by the bones, and are held in place by a ligament which passes over the wrist in much the same way as a watchband. Repeated flexure of the wrist or holding the wrist in a position that compresses the nerve and blood supply results in numbness of the thumb and first 2 1/2 fingers, and can eventually cause muscle weakness and wasting. Carpal tunnel syndrome is also called repetitive motion injury, and is common among factory and assembly workers who continually makes small motion of the wrist. It is also common among persons with diabetes, high blood pressure, obesity, or have sustained injury to the wrist. It is aggravated by inappropriate height and angle of computer keyboards, as in my case, coupled with several of the previous factors.

Diagnosis of carpal tunnel syndrome requires testing of the nerve conduction properties of the median nerve above and below the wrist. An electromyogram or EMG consists of placing electrodes on the thumb to record electrical activity downstream of the wrist, and electrical stimulation of the nerve in the palm, at the wrist, and at the elbow. As I went in for this procedure, it was fortunate that I understood what was going to happen.  I reported to be Diagnostic Neurology in midmorning and was greeted by an EMG technician. She explained that the procedure would be overseen by an attending physician and a clinical fellow, but that she would be my major contact as she performed the tests. She started off by attaching a large ground electrode to the back of my hand, and two smaller electrodes to my thumb. She then made a series of measurements and marks to the middle of my palm, my wrist, and my elbow. These would be the site of stimulation, and she needed the distances in order to be able to calibrate the nerve conduction velocity from stimulator to the electrodes.

The stimulation itself comes as a bit of a surprise. I felt a shock similar to that experienced with a strong static discharge, or for momentarily touching the "hot" leads of an AC cord. Anyone who's ever accidentally touched alternating current will recall that there is a brief momentary pain, and muscle twitch, and a vague "buzzing" feeling for few moments after the shock. After the first several stimulations, the surprise factor goes away, but there is a momentary pain from the stimulation. When applied to the wrist and palm, the pain wasn't too bad. However, the nerve is much deeper at the elbow, therefore the amperage required to get the same reaction had to be increased.  The pain did not last, and was over in less than a second.  In all I suppose it doesn't hurt that much more than when the physician taps on a joint with a reflex hammer. After mapping the nerve conduction from palm to thumb, from wrist to thumb, and from elbow to thumb, the technician "reversed" the stimulation, so that it would travel from wrist to neck and back down to the hand. The sequence was designed to determine where the blockage and nerve conduction was located: wrist, arm, or neck.

After mapping the nerve conduction of my left arm, the technician moved my right and repeated the same studies. About this time the clinical fellow return to the exam room, and they tested the ulnar nerve in my left arm by placing electrodes on my little finger, and stimulating the outside of the wrist, and back of the elbow. A couple of tests were rerun to confirm and then the attending physician was consulted. Again I was fortunate to know my physician, and he explain the condition in terms that I understood. The median nerve was compressed in both of my wrists, causing pain on both sides, and numbness in the fingers of the left hand. Next up would be an ultrasound, to actually look in the carpal tunnel, and perform a few measurements of the nerve. An ultrasound machine was wheeled into the room, sensor head used on the inside of the wrist, to show a cross-section of the blood supply muscles in the nerve as it passed through the carpal tunnel. The attending physician pointing out the median nerve, and makes measurements then moved further up the arm to measure the diameter of the median nerve above the wrist.inside the carpal tunnel, the median nerve was inflamed to 2 1/2 times the diameter that it was further up the arm. I was instructed to make a fist, spread my fingers, and bend and flex my wrist. It was fascinating to watch the muscles move around inside the wrist as I made those motions. The same thing was repeated with my other wrist, with similar results.

So I definitely have severe carpal tunnel syndrome in both wrists. When the nerve becomes compressed, it is injured and the normal body reaction to injury is inflammation. Thus the increased diameter of the median nerve not only contributes to the pain and numbness, but increases the compression on nerve, muscles, and blood supply to the hand. Treatment options are typically "carpal tunnel release" in which the ligament crossing the carpal tunnel is cut to reduce the tension and compression, or injection of steroids to reduce inflammation. The latter is considered a temporary procedure, and in severe cases is used only when it is not possible to perform surgery at that time. I will have to consider these options when I go back to talk to the doctor, but I have several recommendations, including a surgeon whose work is highly recommended by my neurologist friend.

While one part of me is trying to cope with the idea of surgery, the other was fascinated by the procedures used to diagnose this disorder. I have been familiar with electromyography and nerve conduction studies, but had never actually experienced it myself. The neurology team explained that the use of ultrasound is relatively new and provides the type of diagnosis that previously was only possible once a surgical procedure had begun and the doctors could look wrist to determine the severity of the disorder. It is rather fascinating to watch the muscles of the wrist moving around in real-time as you move your hand. In this case the ultrasound was primarily for confirmation, but the ability to measure nerve diameter was an important contributing factor to the overall diagnosis.

So that's my experience, and current status with respect to carpal tunnel syndrome. I present this description is yet another element for understanding brain science, and peripheral nerve science both for writers and readers of science fiction. I hope this has been informative, and may even prompt some of you to receive proper diagnosis if you suspect you have the same or similar condition.

Until next time, as long as y'all are reading, I'll continue dictating.

1 comment:

  1. Fascinating! Thank you very much! I had similar tests done many years ago (without the utltrasound, of course) -- how nice to hear them explained so lucidly! Best of luck in your future treatment!


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