False localization

20-21 Nov 2008:

Sorry for the delay between posts. I’ll catch up, sometimes briefly, sometimes in detail. For now, I’ll briefly summarize the rest of the week on the wards. Briefly, because nothing too dramatic happened. People are still sick, and the hospital is still under-resourced. I spent both mornings rounding on patients on the male ward; I have cherry-picked a few of the interesting ones to help out with (accumulated because they were the only patients for whom I could persuade the interns to seek my help). I saw these patients, left notes, and spoke with the interns about what we thought were the important next steps in their care. Friday we had attending rounds on the male side, which is always helpful.

For the medical aficionados (and with apologies to the rest of you; keep reading only if you’re bored or interested), an update on the patient with the neurological findings from a week ago. Yes, a week ago, and still no head CT. To refresh your memory, he was the young (20 yo) man who had previously been diagnosed with TB meningitis who came in with three months of headache and one month of lethargy; he was unable to look leftwards with his left eye, which had made me think of a problem on the left side of the brainstem, but also had weakness in his left arm, which actually localizes to a completely different part of the brain (the right cerebral cortex, or conceivably a very particular lesion in the left medulla, but in neither case would these two neurological deficits localize to the same place). This is disconcerting to neurologists, because it is much easier to explain one problem in the brain than multiple (especially in a 20 yo man). If a patient has end-stage AIDS, or metastatic cancer, you can sometimes stop expecting parsimony like this, but as I mentioned before (I think), this patient was HIV negative.

This was beyond my current powers of neurological reasoning, and since the only recommendation of the local Neuro consultants (who only come by once a week anyway) was: “pending brain CT” (thanks, folks…), I solicited help from across the Atlantic – Michael Wilson to the rescue! This overseas Neuro consult ended up being prescient; he suggested that the left eye problem might be due to false localization; that particular cranial nerve is very long and therefore most susceptible to elevated pressure in the brain. So he thought it might be possible that the primary problem was in the right cerebral cortex, explaining the left arm weakness, and that the left eye problem was due to swelling in the brain from this lesion. Would be a way to tie all the patient’s symptoms together into one lesion. The day I got Michael’s email, the patient developed the same problem in his right eye (inability to look laterally), which essentially clinched Michael’s hypothesis: it is much more likely that both of these cranial nerve lesions were due to brain swelling than that the patient had developed yet a third separate lesion.

Sure enough, when we (finally) got the CT Thursday afternoon, the patient had a large (3-4 cm) mass in his right cerebral cortex causing the right side of his brain to push over into the left side. I still don’t know what was causing it, and the way medical records are here, I will never know. But we sent him off to the Neurosurgeons to biopsy the lesion and decompress his brain, and perhaps to try to surgically remove or debulk it depending on what it is. This, of course, required hospital transfer; no such thing can happen at our hospital. I am certain that we saved his life in the short term with the corticosteroids we gave him (strong anti-inflammatory medicines that would have decreased the swelling in his brain), but I’m sure his prognosis is not good. Best case is probably that this is all from tuberculosis, which is probably the most likely thing in this region and in a patient of his age. Still, even that would have very high predicted mortality given the size and location of the mass, in addition to which his symptoms had gotten worse on a month of TB treatment.

Anyway, that’s the only thing I recall worth writing about from the end of last week. The rest of the patients I saw were fairly stable; the gentleman with the congestive heart failure and high blood pressure improved quite a bit once we got his BP under control (a triumph!) and the rest of my patients have actually hung in there. For the weekend, Rachel and I are planning to go to a local game reserve for some animal-spotting!