Hitting a Nerve

Diagnosing rare disorders


When I was a resident (back in the Cretaceous era), the idea of autoimmune encephalitis was just beginning to take hold. It was kind of like Bigfoot. A few reports, vague articles, the occasional sighting of what may or may not be a case. …

Unlike Bigfoot, however, the evidence quickly added up until there was no question that such a disorder existed. Then disorder became disorders, and now it seems a few more types are added to the list each year.

Dr. Allan M. Block, a neurologist in Scottsdale, Ariz.

Dr. Allan M. Block

This doesn’t change the fact that they’re still, in the grand scheme of general neurology, relatively rare, though no one questions that they exist.

Today people still wishfully take pictures of Bigfoot, but they turn out to be images of bears or other animals, or tricks of light and shadow.

This is an issue with human thought. Many times we see what we want to see, especially if it’s more interesting than a mundane alternative.

An autoimmune encephalitis article in the January 2023 issue of JAMA Neurology looked into this. On reviewing 393 patients diagnosed with the disorder, the researchers found that 27% of them actually didn’t have it at all. Such things as functional disorders, neurodegenerative diseases, and primary psychiatric diagnoses were, instead, the culprits.

I’m not criticizing those who made an incorrect diagnosis. We all do. That’s the nature of medicine.

Which is worse? Missing the diagnosis entirely and not treating, or diagnosing a patient with something else and treating incorrectly? I guess it depends on the disease and nature of treatment.

Certainly, finding a case of autoimmune encephalitis is more interesting than, say toxic-metabolic encephalopathy from a bladder infection, just as getting a picture of Bigfoot is way more cool than one of a bear with mange.

But we need to be careful when faced with equivocal labs and data lest we read too much into them. There are too many gray zones in medicine to lead you astray. Not to say we won’t be. Even well-intentioned physicians (which I assume is pretty much all of us) are going to make mistakes.

But it’s not just rare diseases. In the early 1990s two different studies found that 24% of patients diagnosed with Parkinson’s disease were found to have something else on autopsy.

That was 30 years ago. Now we have DaT scans to help. Maybe our abilities as neurologists have also gotten better (though I don’t think the neurological exam has changed much since Charcot).

Our gadgets, labs, and treatments get better every year. We have tools available to us now that were unthinkable a generation ago. For that matter, they were unthinkable when I began my career.

But they don’t change the fact that human error never goes away. All of us are susceptible to it, and all of us make mistakes.

Such is the way of medicine now, and likely always. All we can do is our best and keep moving forward.

Dr. Block has a solo neurology practice in Scottsdale, Ariz.

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