Altered mental status and the neuro consult
Yes, the consult pager gives me nightmares. But it doesn’t have to. A few solid tips for the general practitioner can save your consultant from a world of hurt. And I think it’s good advice for you as well when you end up setting off someone else’s pager. In this week’s episode of BrainWaves, you get a 2-for-1 deal: Consult advice + Basic elements of working up altered mental status. Take a listen:
Rule no. 1. Don’t request a consult to “have neurology on board.” Have a specific question in
mind, and ask it. Whenever Ali Hamedani (from our neuro-ophtho series) gets asked to “be on board,” he likes to ask, “Where are we going?”
Asking for a consult just to have a consult is not a perfectly benign request. Say you have a patient with multiple medical problems, and you’ve hit a roadblock in the management of the patient because they are altered, and you want neurology “on board.” But in the absence of an obvious question, a consultant will lack direction in which to proceed with the patient. The consultant might recommend an extensive battery of diagnostic tests, imaging, and invasive studies to answer any neurologic question imaginable. Or they might neglect the one key feature for something less concerning but more obvious.
Rule no. 2. A history is worth a thousand words. Timing is critical here. There’s an oceanic difference in the causes of altered mental status between a patient who was normal 2 hours ago and who is normal every 2 hours. An acute change in behavior, meaning a change over seconds to minutes, is concerning to me for only a two things: a vascular event like stroke or hemorrhage, or a seizure. In contrast, say the altered mental status developed over several hours or days. Now I am thinking something more systemic, possibly metabolic, infectious, or inflammatory. Any change in mental status that progresses over days or weeks is now exiting the realm of altered mental status and encroaching on the rapidly progressive dementias, tumors, toxicities, and other diagnostic categories.
Next, consider how the patient is altered. What is the delta of the change? If your patient was a young and healthy woman who came in with 2 weeks of visual hallucinations and personality changes, then I’m going to worry a lot about toxic, metabolic, infectious, and inflammatory causes of encephalopathy. If your patient is an elderly woman with dementia, and has been dependent for all ADLs, I am not going to panic as much if she’s now become forgetful of where the channel changer is. But say this elderly woman has a visual hallucination, now I’m wondering, do they have dementia with lewy bodies? Have they tried new medications? Could this be a seizure or related to an underlying mass or stroke? Use your noggin’ here.
Rule no. 3. Rule out acute neurologic emergencies. By this, I really mean stroke or hemorrhage. A lower state of arousal with or without eye movement abnormalities or facial weakness is concerning for a brainstem or top-of-the-basilar infarction. An intracerebral hemorrhage or large stroke of the cerebellum can produce subtle neurologic symptoms but swell to the point of occluding the fourth ventricle causing obstructive hydrocephalus. And if you’re not confident in your exam skills, as a neurology or non-neurology provider, call the consult for this. You don’t want to delay treatment for something with an acute cerebrovascular event.
Besides things like stroke, other neurologic emergencies can be excluded with basic exam and diagnostic testing. A fever can impair the alertness of any adult, no matter how healthy they once were. And in kids, fevers can cause seizures. Hypotension and cardiac arrhythmias may impair cerebral perfusion. A capillary glucose level is a quick and easy test, and both hyper and hypoglycemia can cause altered mental status. Sometimes a rapid shift in blood sugar can also cause focal neurologic deficits mimicking stroke, or it can cause seizures. In a patient with possible organ dysfunction, asterixis, or fluctuating consciousness, get the metabolic panel, liver studies, and an ammonia level. Hyperammonemic encephalopathy can cause severe cerebral edema and coma if not managed swiftly and appropriately. And so on, and so on…
Rule no. 4. Be the first person to do the neuro exam. I know this sounds dumb. But I’m completely serious here. I’ve been consulted by a neurosurgeon before about a question of Guillain-Barre syndrome in a patient with severe lumbar stenosis. When I asked what the reflexes were, I guess I shouldn’t have been surprised that the surgeon didn’t test for them. I mean, really? You didn’t even test the reflexes? A neuro consult is not meant to be used for a neurologic exam. The same goes for all the other specialties. Except maybe ob/gyn. But if you’re calling vascular surgery for a patient with suspected compartment syndrome, you better have checked for pulses. As far as the neurology exam goes, do your best to get a basic sense of the patient.
That’s a wrap for week 46. Hope you learned something from this episode. And if you didn’t, pass this on to someone who would.