Neuro Clinical Correlations

Today was another double seminar day. The first one was about the genetics of dementia, and for the second they showed us video clips of patients with various movement disorders. I liked the genetics seminar, which was a case with a sort of surprise conclusion. The other one was ok, but somehow I just couldn't keep focused. Maybe it's just a matter of it being the last hour of class and the room being nice and dark.

In the afternoon, we had two clinical correlations. The first one involved examining a patient with multiple sclerosis in small groups, which was interesting. But I felt sorry for the patient, who seemed to be pretty tired and kept dozing off in between getting various joints and muscles prodded and poked by us. Afterward, we got an hour-long seminar about MS, which wasn't bad, but it was too long. We had several questions for the speaker, and he had clearly not built in time for questions in his talk. So he started getting a little testy with us for asking so many questions, and we wound up arriving at the EMG lab about 20 minutes late.

EMG stands for electromyography, which is a fancy word for testing the electrical conduction in muscles. They asked us to volunteer for some of the tests, and I did one called a QSART where they administered acetylcholine (a neurotransmitter) to my skin and measured how much it made me sweat. This tests the small nerve fibers that are attached to the sweat glands. I am apparently a slow sweater, because we had to wait a few minutes before anything happened. It doesn't make you sweat gallons or anything--they just collected on the order of a nanoliter of sweat, which is 1 x 10^-9 liters. Two of my classmates did the other tests, one to test breathing and one to test pupillary reflexes. That pupillary one was really cool. We could see his eyes on the computer screen, and when the light flashed, his pupils would contract.

Afterward, we went to a second room to do nerve conduction studies. No one wanted to volunteer, so I did those too. First, they put two electrodes on my hand, and when they then applied a current, it made the muscle contract. That test looks to see if my nerve cells have lost their myelin in some segments. (Myelin is the "insulation" that covers your nerve cells.) It's kind of a weird feeling, because each time the tech turned on the current, my thumb would jerk, and I had no control over it whatsoever. It didn't really hurt though until they moved the current up to my elbow and made my whole arm move. That felt a lot like banging my funny bone, and it was not too pleasant. The second test involved sticking a needle into my thumb muscle. That test is to look for loss or degeneration of my nerve cell axons. The needle is really small, so it didn't really hurt, and the tech said my readings were normal for a young adult. What a relief!