Saturday, July 3, 2010

Summer Immersion Week 3

This week I was able to observe several more neurosurgeries with Dr. Kaplitt, see more patients with Dr. Gauthier and get more work done on my summer project for Dr. Gauthier.

With Dr. Kaplitt I observed two surgeries. The first was the implantation of two electrodes into the brain of a patient who suffered from an essential tremor. The purpose of these electrodes is to stimulate the thalamus of the brain to hopefully reduce the tremor that the patient experienced. With this surgery I was able to see the actual hardware of the electrical stimulators that I had learned about the previous week. One unnerving aspect of this surgery was that throughout the entire neurological procedure the patient was awake; both conscious and talking. It was necessary for the patient to be awake through the procedure to monitor the patients’ ability to function; as the brain is one of the most complicated and important control organs in the body. To test the patients’ ability to move his hands the patient was asked to move his hands in certain way or to remain still as a nurse passively moved the patients’ extremities. Throughout this entire process the patients’ EEG and signal from the electrode was monitored on both a computer screen and as an audio signal. It was this part of the procedure I found most difficult to follow. It was the signal from the electrode that informed the surgeon as to what kind of area in the brain the electrode had been placed; oddly enough as I said one of the ways this was monitored was as an audio signal. This audio signal, to me, sounded exactly like static; there were what I would have considered minor fluctuations in the amplitude and frequency of the static, but otherwise it was as indistinct a noise as I can think of. As the surgeons positioned the electrode nearer its target location in the brain this process of listening to and monitoring the recordings from the electrode was called listening for cells. Though it clearly requires experience to differentiate the proper signals to look for in these recordings the surgeons were successful and appeared to achieve a good initial response from the patient. This procedure was only the placement of the electrodes; the implantation of the signal generator to drive the electrodes will be implanted at a later date. The second surgery I observed with Dr. Kaplitt was the revision of a spinal stimulator in the upper thoracic region of the spine. The equipment implanted in to the body was virtually identical, in function not form, to the deep brain stimulator. The only difference being that the electrode was designed specifically to fit within the thin space between the spinal cord and vertebrae.

Later in the week I was able to observe an MS clinic with Dr. Gauthier. In the clinic I could observe how residents presented cases to Dr. Gauthier. The clinic setting was somewhat different than meeting patients in Dr. Gauthier’s office; these patients had a much wider range of background histories and some of them were meeting Dr. Gauthier for the first time. As the resident presented the cases I noticed that there was a great deal of information that was transmitted between Dr. Gauthier and the resident verbally. Clearly from the interactions between the doctors and patients they were able to approach each patient’s case and form a plan of treatment or further investigation. It is easy to see that patients with the same disease begin to follow predictable patterns, but it is still clear that in individual cases there are a lot of details that may play an important role in the patients’ course of treatment. It appeared to me to be one of the doctor’s challenges to retain and interpret all of the presented for an individual patient effectively.

I have also made some progress on my summer project this week. My summer project is to help with Dr. Gauthier’s research in investigating the health of myelin using MRI (Magnetic Resonance Imaging). MRI is unlike other imaging modalities in that signal that the tissue generates is highly depended on the underlying chemical structure and environment, which permits different tissues to emit distinct signals. This week an experiment was conducted to gather image data from a 7T (Tesla) scan of a normal mouse and a mouse model of demyelination. The image data from the mice will be used to fit curves of decay that are intrinsic to the MR signal. Essentially varying rates of decay will provide an indication of differing chemical structures of the mouse’s brain non-invasively.

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