Tuesday, May 10, 2005

LCE Large Group Presentation

On Wednesday, May 18, I will be doing the large group presentation during LCE.
This basically works like the New England Journal of Medicine's clinical case discussion.
The idea is that I pick out a case that has a good differential and bring it in for presentation. You start with the Chief Complaint (young adult male presents with Vomiting) and allow responses from the students to guide your from there - meaning, they would ask for physical exam findings, come up with a differential, ask for the positive/negative indicators, lab values, images, etc and come up with a more refined differnential. The attending physician usually comes in as well and it makes for a fairly entertaining hour and a decent little thought exercise - granted we don't really know any of the pathology right now so the logic behind our guesses at the differential is kinda shaky at best.

Anyway, Dr. B will be coming in and he is bring a cadre of people with him including Dr. M, a radiologist, and Dr. N, a neuroanatomist. So this means I probably won't have to say too much -fine by me.
It is advantagous to volunteer for these because you are then allowed to pick your next LCE preceptor - which allows me to ensure I get someone in Tampa (driving to Sarasota, Spring Hill, Lakeland, etc doesn't sound too fun) and hopefully someone in ID or EM.

Dr. B agreed to assist and allowed me to select the case - however, he made a push for a recent gunshot wound to the neck which would have allowed us to discuss trauma and stroke. However, we did a stroke in February and trauma doesn't allow for as much consideration in the differential.
Since we are currently in our neuro block, and I'm rotating with a neurosurgeon, I thought it would only be appropriate to do something with all the classic neuro exam signs.

We saw this patient on hospital rounds - a 25 year old male with persistent vomiting, nausea and headache. Apparenty, the bouts of nausea had been occuring for approximately 8 months, however, in the last few months, frequency and severity were increased and accompanied by a number of other symptoms, including headaches and transient confusion (described by his wife). The patient presented to hospital when the nausea began to occur with headaches during the middle of the night.

It is important to note that vomiting presented first. This led initial diagnoses to focus on the GI system. However, lab data came back negative and the presence of headaches with vomiting led to a neuro consult.

On exam, there were a number of important signs. Muscle tone was reduced on the left side, an ataxic gait was present (stumbling), and nystagmus was noted (eyes don't catch up to tracking an object). There was rebound phenomenon in the left upper limb (left arm bounces after lifted and dropped) but no Hoffman's sign or clonus (both tests for upper motor neuron lesions).

These findings are quite significant with a neoplasm (brain tumor), specifically in the posterior cranial fossa. While the majority of brain tumors occur in cerebrum (astrocytomas), the presence of coordination problems and nystagmus leads one to suspect that the tumor may be in the cerebellum.

An ependymoma would be the most likely type of glioma to consider. Ependymomas occur in the ependymal cells within the 4th ventricle. This can push on the ventricle wall, causing vomiting and block the pathway for cerebrospinal fluid to flow out of the ventricle, thus causing increased cranial pressure leading to heaches.

An MRI was obtained to confirm this diagnosis, however, the tumor was, suprisingly, not in the ventricle at all. As a matter of fact the tumor appeared to be a medulloblastoma - which are congenital tumors that often appear in the cerebellum during childhood. They do have a similar presentation - but headache usually comes before vomiting with these types of growths.

So here was a 25 year old male, too old for a medulloblastoma and presenting symptoms more likely to be an ependymoma. However, it is possible that 25 year old males can get medulloblastomas, and this is the case here.

Upon surgery, a portion of the occipital bone was removed and the tumor was excised. A number of weeks later, the patient received a lumbar puncture. It is important to do a lumbar puncture to check for drop metastases where cancer cells metastasize via CSF pathways into the spinal cord.

Unfortunately, in this case, the lumbar puncture was positive meaning that the cells had indeed spread into the spinal sac. At some point a tumor will occur along the spinal cord and can also reoccur in the cerebellum and will most likely lead to death.

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