werner@aecom.UUCP (Craig Werner) (02/27/86)
<<<>>> > A 52-yr old housewife comes in with two complaints. Over the past few > months, she had dropped 7 dishes, and had to switch to washing dishes with > her left hand, at which point the china breakage stopped. She also said that > she had trouble holding a pencil while writing, and dropped it repeatedly. > She also has another symptom, but hasn't noticed it. Additionally, > there are findings you can elicit on physical exam. To tell you which would > give away the answer. > What is the most likely diagnosis? Taking the above description at face value, frankly it could be anything. In fact my test run with John Wurzelmann produced the following: >> My differential diagnosis would include myasthenia gravis, diabetic >> mononeuropathy, amyotrophic lateral sclerosis, & carpel tunnel syndrome. >> Other diagnostic possbilities include lead poisoning, syringomyelia, >> myotonic dystrophy (I don't think it's X-linked), shoulder-hand syndrome. which is as good a list of diseases as I can come up with. However, let's go at systematically from the top. She could have had a localized (lacunar) stroke, but she is a little young, and would have to have an extremely high blood pressure. Trouble in the spinal cord would probably be bilateral and associated with distal (leg/trunk) weakness, or be associated with pain. Any systemic disease like Myasthenia gravis (an autoimmune disorder of the motor end plates which is rare, but common enough to afflict at least one net.med reader) or Heavy Metal Poisoning or B6 overdose or B12 deficiency, or most common, Diabetes would probably present globally, not localized to one hand. Diabetic mononeuropathy (as opposed to poly-) does occur rarely, but would be part of a spectrum of symptoms associated with Diabetes. (Polyneuropathy on the other hand is very common if the diabetes is not properly controlled.) In this respect, since we know the problem is in right hand, the best place to start the neurologic exam is either in the LEFT hand, or the left FOOT. Verifying that these are normal would eliminate a lot. Out of the central Nervous system, we have the peripheral nerves, and the most common cause of localized damage to them is trauma or inflammation. So the next question is: where is the problem? Right hand. Does it extend up the arm? (No). There was trouble holding a pencil, you say. How do you hold a pencil? (Two fingers and the thumb) The missing symptom: those fingers and that thumb are numb - when comparing a pin-prick to the opposite hand. (The patient should close their eyes for this, otherwise they cheat.) Well, that makes the diagnosis. Now if I had phrased the case, "a menopausal woman comes into your office with localized sensory loss in the right median nerve distribution" you would have said, "That's obvious." But patient's don't do that, they come in complaining of dropped dishes and pencils, and if they do come in complaining of median nerve dysfunction, the odds are they don't have it, although you had better ask how they got such a notion. Their child the doctor is probably a more reliable source than a friend of their neighbor who just had a similar problem. The diagnosis: Median Nerve compression, also called Carpel Tunnel Syndrome - because the Median nerve travels through the sheath (tunnel) of the carpel (latin for wrist) synovium (lining of a joint). The median nerve is responsible for the Sensory aspects of the the front of the thumb and adjacent 2 1/2 fingers, the Ulnar is responsible for the little finger and adjacent 1/2. The Radial nerve covers the back of the hand but not the nailbed. Only the Median nerve travels inside the synovial sheath, the others are outside and cannot be similary compressed. The compression occurs when the synovium becomes inflammed, either due to injury, or non-specifically. The latter type occurs most often in women, and is especially frequent during pregnancy and menopause. -- Craig Werner !philabs!aecom!werner "Never go to a doctor whose office plants have died."