The Dark Truth Behind the 4% Misdiagnosis Rate in Functional Neurological Disorder

05 Jul 2025

When presented with a misdiagnosis rate for FND of just around 4%, it sounds impressive - who wouldn’t be tempted to jump on the bandwagon? Surely this means doctors have the disorder all figured out, backed by mountains of rock-solid, empirically proven evidence. Right? A disorder that is believed to live on the fringes of neurology and psychiatry - what could possibly go wrong? Stone et al., 2005, BMJ (doi:10.1136/bmj.38628.466898.55) Stone et al., 2010, Brain (doi:10.1093/brain/awq068) Carson et al., 2012, JNNP (doi:10.1136/jnnp-2011-301993)

A claimed diagnostic accuracy of 96% (up to 99%) for a diagnosis made entirely clinically, without a biomarker or independent confirmatory test, implies near expert accuracy among almost all clinicians making the diagnosis, rather incredible.

One glaring issue is that this percentage comes from seemingly limited, retrospective pre-FND (conversion disorder) criteria studies, making it hard to judge data quality or completeness (I would love to get my hands on that data), but let’s just pretend that’s fine for now.

If, however, we consider that FND is a disorder that is conceptionally defined into existence, then applying percentages to this disorder seems inappropriate, a category error akin to declaring referred pain an illness and sending all cardiology patients home.

However, if we accept and invert this percentage and view it through the lens of a traditional understanding of functional disorders (traditionally used as placeholders and still very much so in a lot of cases), it reveals a darker truth. Nettleton S. (2006). 'I just want permission to be ill' Barsky AJ, Borus JF. (1999). Functional somatic syndromes

It would literally mean that a staggering 96 percent of patients in the reviewed practices included in these studies never found a real answer for what is truly wrong with them (Doctors bragging about the misdiagnosis rate being as low as 1% might want to take a moment for some serious introspection).

Could this reflect diagnostic bias (e.g. once a FND diagnosis was made, further investigation stopped) or a genuine inability to find any underlying causes, due to limitations in current medical knowledge or technology? Croskerry, P. (2013). From Mindless to Mindful Practice — Cognitive Bias and Clinical Decision Making. Or could the constant comorbidity claims simply act as a diagnostic shield, making the disorder unfalsifiable? Once comorbidities are layered on, misdiagnosis becomes almost impossible to prove.

Given this quote from the DSM-5, "After a thorough neurological assessment, an unexpected neurological disease cause for the symptoms is rarely found at follow-up," I suspect that the former is at play here. American Psychiatric Association, DSM-5, p. 364

Don’t get me wrong. If FND is simply used as a construct, for example, when doctors cannot pinpoint what is wrong with their patients but can at least provide some kind of generic treatment plan through a multidisciplinary approach, it might provide relief to some (in addition follow-ups to assess and re-assess symptoms should be required once this diagnosis was made).

We shouldn’t throw the baby out with the bathwater.

Comments

10 months ago by Romina S

Replied to The Dark Truth Behind the 4% Misdiagnosis Rate in Functional Neurological Disorder

Bravo and THANK YOU for this website! Very clever name, too, may I add! I agree wholeheartedly that this latest iteration of "hysteria" is highly dangerous to patient welfare, illogical, unscientific, and absolutely asinine! I also think it an utter disgrace that female doctors have attached their names to this diabolical garbage, calling it a "feminist issue", while applauding the stigmatization and disenfranchisement of said female patients whom they pretend to "protect". Just recently, when viewing the Cleveland Clinic's page for FND, I noticed how quickly they reveal it was "formerly conversion disorder", as though that distinction were unnecessary and the former status remains relevant and inextricable from its current classification; and yet, they explain it can no longer be deemed a [psychosomatic] "mental health disorder" due to newer evidence from fMRI studies revealing "altered brain signaling". According to their circuitous rationale, somehow, this merely serves as further evidence of a so-called "software" vs. "hardware" issue and not a matter worthy of proper investigation and analysis beyond their hackneyed treatment recommendations with CBT, psychodynamic therapy, physical therapy, and neurotropic meds (for e.g., anxiety and depression). Meanwhile, the associated set of symptoms include sensory abnormalities, seizures, fainting, muscle weakness, paralysis, dizziness, dysphagia, tremors, brain fog… WOW! Who knew talking things out with a therapist or several sessions with a physical therapist could easily reverse poor blood flow or "misfiring signals" to the brain?! Or better yet, reverse paralysis, cognitive decline, debilitating pain, fatigue, vertigo, etc.

10 months ago by Christoff Trüter Spousal caregiver

Replied to The Dark Truth Behind the 4% Misdiagnosis Rate in Functional Neurological Disorder

FND is nothing more than a philosophical framework for approaching treatment when the cause of symptoms is unknown — so while it may be well-intentioned, that’s all it really is. However, the road to hell is paved with good intentions, and this is a clear example of that. When we reach an impasse like this, we cannot simply give it a name and declare victory in diagnosis. We need to be honest and transparent, and acknowledge the unknown as exactly that — unknown. For example, in my wife’s case, we cannot expect a psychiatrist to do the work of a neurosurgeon when it comes to her cervical stenosis and symptoms that are clearly mechanically driven. That’s simply lazy medicine. Meanwhile, she continues to grow sicker while we’re forced to navigate the egos of one doctor after another.

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The Dark Truth Behind the 4% Misdiagnosis Rate in Functional Neurological Disorder

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