Monday, June 6, 2016

WILTIMS #496-7: Ohhh myyy-a!

FridayIL: The only place in the body where an artery empties into a larger vessel is at the junction where the vertebral arteries become the larger basilar artery. To get an idea of how weird this is it would be like two branches of a tree growing into each other to form a single bigger branch.

The only purely visual manifestation of an increased intracranial pressure due to hydrocephalus (too much cerebrospinal fluid in the head) is an increase in the area of the blind spot that everyone has in their eyes. This normal blind spot is caused by retina having a hole in it where the optic nerve enters the eye. If you have too much fluid/pressure, this hole can stretch wider. This symptom would be great for speeding up diagnosis, but it's very hard to notice or test. Do you notice your blind spots now? Would you notice if they doubled in size? Probably not.

Monday: Today I switched over to the consult team. Much like my two elective rotations in pulmonology and nephrology, on this service, the patients' primary problems are not neurological, but the primary team wants us to take a look for some reason. Compared to my previous neuro teams, the patients in this group are far more diverse in presentation (and interesting, imho). Whereas on epilepsy all the patients were being worked up for some form of seizures, and on the stroke team we saw variations on stroke, consults could be anyone in the hospital with any vaguely neurological complaint. One guy was shot in a gunfight, another had a heart attack, one fell and broke her leg, and someone else had muscle breakdown after a likely overdose. Sometimes our team's involvement is extensive, other times it's very brief. The consult for the lady who fell and broke her leg simply asked if we thought anything neurological could explain the fall. We're pretty darn sure that this was blood pressure related, not neurological, so we write a note to that effect for the primary team, and we probably won't see that patient again on this admission.

An ommaya reservoir
MondayIL: {This fact is very boring; feel free to skip below.}You can differentiate between a sciatic nerve injury and sacral plexus/spinal nerve root injury by testing the gluteus medius muscle. The leg nerves and all the gluteal nerves come through the same roots and nerve plexus, but the superior gluteal nerve which innervates the gluteus medius muscle breaks off from the rest after the sacral plexus but before the consolidation of the sciatic nerve. So if a patient has leg weakness and has difficulty abducting the leg (lifting it to the side) the injury is likely proximal to the start of the sciatic nerve.

An ommaya reservoir is a port that gives you access to the cerebral spinal fluid within the brain. It can be used to remove fluid just like a lumbar puncture (aka spinal tap) or to administer chemotherapy for a brain tumor in or around the ventricles of the brain. Patients with one of these have a little plastic bubble on or under their scalp that connects with a tube to the space in the middle of their brain. Trippy.

For people with a congenital valgus leg deformity ("knock-knees"), having a knee replacement surgery can cause nerve injury. The peroneal nerve normally runs very close to the head of the fibula, but in valgus people, there is often more space between these structures. A knee replacement surgery will fix the angle of the leg and put normal pressure back on the nerve. But as the nerve in one of these patients isn't used to that pressure, it reacts like it's being pinched, causing numbness and/or weakness.

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