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Interesting Neuro Case Requires ER Doc To Recall Forgotten Med School Knowledge

Yesterday, I presented the case of a woman with double vision and ptosis and challenged you all to a game of “spot the lesion.” To be honest, I found this stuff impenetrable as a medical student and it was only by sheer force of will that I was able to commit it to memory for exactly long enough to pass a test on it before immediately purging it from my memory. I did this several times for various board exams and such, but it never really “stuck.” Hated neuro beyond words, I did.

As mind-numbing as I found it all in the abstract, I get excited about these cases in application. I may not remember where exactly the internal capsule is or what it does, but when I see someone with an interesting neuro deficit due to a lesion there, all of a sudden it makes so much more sense, and is, dare I say it, cool. I know, kinda sad.

This case is as classic (and cool) as you will ever see. It’s a complete palsy of the Oculomotor Nerve (CN 3 for those keeping score at home).

So how do you approach figuring that out?

First of all, it’s unilateral. Note the movements of the left eye are all normal. Some other things, systemic diseases, can cause ptosis (the droopy eyelid) or diplopia (double vision) — think neuromuscular stuff like myasthenia gravis, botulism, etc. But those are usually bilateral. As an isolated right-sided finding, however, that should prompt you to think about either a central cause or a direct neuropathy. But central causes of this sort of thing are not likely, because the oculomotor nuclei are located deep in the midbrain, and are crossed, so a stroke or something bad there is not likely to give unilateral or isolated neurological findings. Therefore, we know it’s a peripheral neuropathy. Yay! But which one?

The ptosis — especially a complete paralysis of the levator palpebrae — should be a huge red flag that the third nerve is involved. Even I remember this mnemonic from medical school:

The III is the pillar that holds the eye open; the 7 is the hook that closes it. Then you look at the pattern of movements that the eye has lost and note that it matches the oculomotor muscles which are innervated by the third nerve:

extraocular muscles
She can abduct it, so CN6 is intact, but up, down and adduction are shot, which are all CN3. The fact that with straight gaze and lateral gaze the right eye is a bit down compared to the left is due to the preserved function of CN4. Thus, the classic pattern of CN3 palsy — “down and out.”

Then you look at the pupil. It’s big — so you know this isn’t a Horner’s syndrome, though that wouldn’t cause ophthalmoparesis either. And it’s not reactive, either. The most common cause of acquired CN3 palsies is diabetic microvascular ischemia — one of the many peripheral neuropathies that the sugar causes. But those are usually pupil-sparing. This involves the pupil, so something is compressing or otherwise pissing off the nerve directly.

The solution (as for just about everything in neurology, it seems) is to order your MRI, but in this case, you definitely want an MRA as well. Because the next most common cause of CN3 palsy is compression by an aneurysm (notoriously the PCA – posterior communicating artery). The deficit can apparently be intermittent with an aneurysm. But all sorts of things can do it, and the treatment will depend on the cause. It could be direct compression from a pituitary tumor, or a cavernous sinus thrombosis. If the patient presents with stiff neck and meningismus, either subarachnoid hemorrhage or meningitis should be considered, as they can do this. Demyelinating diseases can also do this, so if all else fails and if the demographic makes sense, consider MS. In older patients, consider arteritis, too. Herpes zoster can also rarely do this, though it’s more classically the seventh nerve. These can occur post-traumatic, but be sure that the pattern of the deficit matches the nerve and that you’re not going to miss an orbital wall fracture! I recently saw a patient with a port-traumatic transient internuclear ophthalmoplegia, which was also pretty cool. Sadly, I didn’t have the presence of mind to get pics of that one.

In the incident case, the MR showed a suprasellar mass invading the cavernous sinus, most likely a pituitary macroadenoma:

suprasellar

Not something you can see commonly, but very classic, and a nice opportunity to review and relearn all the neuroanatomy we learned in medical school, but in the context of a real case.

*This blog post was originally published at Movin' Meat*


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Richmond, VA – In an effort to simplify inpatient medical billing, one area hospitalist group has determined that “altered mental status” (ICD-9 780.97) is the most efficient code for use in any patient work up.

“When you enter a hospital, you’re bound to have some kind of mental status change,” said Dr. Fishbinder, co-partner of Area Hospitalists, PLLC. “Whether it’s confusion about where your room is located in relationship to the visitor’s parking structure, frustration with being woken up every hour or two to check your vital signs, or just plain old fatigue from being sick, you are not thinking as clearly as before you were admitted. And that’s all the justification we need to order anything from drug and toxin screens, to blood cultures, brain MRIs, tagged red blood cell nuclear scans, or cardiac Holter monitoring. There really is no limit to what we can pursue with our tests.”

Common causes of mental status changes in the elderly include medicine-induced cognitive side effects, disorientation due to disruption in daily routines, age-related memory impairment, and urinary tract infections.

“The urinalysis is not a very exciting medical test,” stated Dr. Fishbinder. “It doesn’t matter that it’s cheap, fast, and most likely to provide an explanation for strange behavior in hospitalized patients. It’s really not as elegant as the testing involved in a chronic anemia or metabolic encephalopathy work up. I keep it in my back pocket in case all other tests are negative, including brain MRIs and PET scans.”

Nursing staff at Richmond Medical Hospital report that efforts to inform hospitalists about foul smelling urine have generally fallen on deaf ears. “I have tried to tell the hospitalists about cloudy or bloody urine that I see in patients who are undergoing extensive work ups for mental status changes,” reports nurse Sandy Anderson. “But they insist that ‘all urine smells bad’ and it’s really more of a red herring.”

Another nurse reports that delay in diagnosing urinary tract infections (while patients are scheduled for brain MRIs, nuclear scans, and biopsies) can lead to worsening symptoms which accelerate and expand testing. “Some of my patients are transferred to the ICU during the altered mental status work up,” states nurse Anita Misra. “The doctors seem to be very excited about the additional technology available to them in the intensive care setting. Between the central line placement, arterial blood gasses, and vast array of IV fluid and medication options, urosepsis is really an excellent entré into a whole new level of care.”

“As far as medicine-induced mental status changes are concerned,” added Dr. Fishbinder, “We’ve never seen a single case in the past 10 years. Today’s patients are incredibly resilient and can tolerate mixes of opioids, anti-depressants, anti-histamines, and benzodiazepines without any difficulty. We know this because most patients have been prescribed these cocktails and have been taking them for years.”

Patient family members have expressed gratitude for Dr. Fishbinder’s diagnostic process, and report that they are very pleased that he is doing everything in his power to “get to the bottom” of why their loved one isn’t as sharp as they used to be.

“I thought my mom was acting strange ever since she started taking stronger pain medicine for her arthritis,” says Nelly Hurtong, the daughter of one of Dr. Fishbinder’s inpatients. “But now I see that there are deeper reasons for her ‘altered mental status’ thanks to the brain MRI that showed some mild generalized atrophy.”

Hospital administrators praise Dr. Fishbinder as one of their top physicians. “He will do whatever it takes to figure out the true cause of patients’ cognitive impairments.” Says CEO, Daniel Griffiths. “And not only is that good medicine, it is great for our Press Ganey scores and our bottom line.”

As for the nursing staff, Griffiths offered a less glowing review. “It’s unfortunate that our nurses seem preoccupied with urine testing and medication reconciliation. I think it might be time for us to mandate further training to help them appreciate more of the medical nuances inherent in quality patient care.”

Dr. Fishbinder is in the process of creating a half-day seminar on ‘altered mental status in the inpatient setting,’ offering CME credits to physicians who enroll. Richmond Medical Hospital intends to sponsor Dr. Fishbinder’s course, and franchise it to other hospitals in the state, and ultimately nationally.

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