Trial By Error: FND Experts Agree To Correct Inflated Prevalence Claim

By David Tuller, DrPH

For years, experts in functional neurological disorder (FND) have cited a seminal study in their field to claim that the diagnosis was the second-most-common presentation at outpatient neurology clinics, with a prevalence of 16%. This claim was, and is, categorically untrue. The Scottish Neurological Symptoms Study (SNSS), which yielded multiple papers about a dozen years ago, actually found that 209 out of 3781, or 5.5%, were identified as having conversion symptoms. (Conversion disorder is the old name for FND.) At that rate, it was the eighth-most-common presentation in the SNSS, not #2.

This discrepancy was pointed out to me a year or so ago by a valued source. I blogged and posted on social media about the issue. I also wrote—twice–to a major journal seeking a correction in one such paper. I received no response. Two weeks ago, I sent a letter seeking a correction to another major journal, NeuroImage: Clinical. Several colleagues—from Berkeley, Columbia, Johns Hopkins, University College London, etc—co-signed the letter.

The authors have now agreed to correct the false statement that the SNSS found FND to be the second-most-common presentation. The correction is inadequate in some respects. Nevertheless, I hope it means that they will at least no longer cite the SNSS to claim FND is the #2 presentation at outpatient neurology clinics, with a prevalence of 16%. I also hope the FND experts themselves will now initiate corrections in the dozens of papers that have included these untrue data points. It will be a tedious process for all involved if our group has to send out letters to journal editors about every single one of these papers.

I need to say I was impressed with the speed with which the journal handled our request. Within five days of sending our initial letter, I heard back from an editor, Anna Bonkhoff* [I initially misspelled this name as Bankhoff. I apologize for the error.] who was seeking our group’s input about proposed language for a correction. I attributed this quick action to the integrity of the journal; the authors themselves have previously exhibited little interest in responding to these concerns and cleaning up the mess. The authors presumably understood that a correction in one paper meant it would be hard to object to requests for corrections in every other paper with the same misinformation.

This was the sentence in question: ““This renewed interest [in FND] parallels recognition that FND is the 2nd most common outpatient neurologic diagnosis, with many patients remaining chronically symptomatic and incurring high healthcare costs.” The reference was to Stone et al, a 2010 paper arising from the SNSS.

The initial proposal from the authors was to remove the #2 claim and simply say that FND was a “common” presentation. We responded, as a group, that we found that solution inadequate. Here’s what we wrote:

Dear Dr Bonkhoff–

I have consulted with my colleagues, and first we would like to thank the journal and the authors for promptly acknowledging that Perez et al includes an error requiring a corrigendum. I think it’s fair to say that this sort of swift action does not happen frequently in academic publishing, so it is very much appreciated.

As regards the proposed wording, we believe it is definitely a step in the right direction but not in itself sufficient. The original sentence compared FND to other diagnoses by calling it the second-most-common presentation while inaccurately citing findings from the Scottish Neurological Symptoms Study (SNSS). To undo the misimpression generated by this claim, the replacement sentence should also place FND in the context of other diagnoses.

From our perspective, calling it “common” and leaving it at that is not enough. First, the understanding of “common” is dependent upon the circumstances. Readers of the article could easily assume “common” means 20% or 30% or 40% of patients–not 5.5%. Second, the proposed phrasing doesn’t indicate that FND was not, after all, the #2 diagnosis in the SNSS but down the list at #8—after headache, epilepsy, peripheral nerve disorders, miscellaneous neurological disorders, multiple sclerosis/demyelination, spinal disorders, and Parkinson’s disease/movement disorders. Therefore, referring to FND as “common” would not fully address the problem created by the original misstatement in the first place.

(As a side note, the phrase “outpatient neurologic diagnosis” is ambiguous and could easily be misinterpreted to mean that these diagnoses were made in primary care and not in secondary care settings–i.e. neurology clinics.)

Another consideration: Two of the co-authors of Perez et al, Professors Alan Carson and Jon Stone, are also co-authors of a new paper called “Functional neurological disorder is common in patients attending chronic pain clinics,” published on May 23rd in the European Journal of Neurology. Citing the SNSS findings, this article reported that “the prevalence of typical FND in patients attending neurology outpatient clinics is 5.4%.” (Since this “typical FND” group included 209 out of 3781 patients, as we noted in our original communication with you, it is unclear why the figure given is 5.4% and not 5.5%.) 

Given this most recent definitive statement about the SNSS, it seems reasonable to suggest that Perez et al make a similarly clear account of the prevalence of “typical” FND. We recommend one of the following options to replace the original sentence:

“This renewed interest parallels recognition that FND is a relatively common diagnosis in neurology outpatient clinics, being found in 5.5% of referrals, with many patients remaining chronically symptomatic and incurring high healthcare costs.” (Or 5.4%, if our calculation is somehow wrong.)

“This renewed interest parallels recognition that FND is a relatively common diagnosis in neurology outpatient clinics, being found almost as often as multiple sclerosis and Parkinson’s, with many patients remaining chronically symptomatic and incurring high healthcare costs.”

Thank you again for the opportunity to comment on this proposed correction involving the erroneous citation in Perez et al. We look forward to the resolution of this matter. 


David Tuller, DrPH
Senior Fellow in Public Health and Journalism
Center for Global Public Health
School of Public Health
University of California, Berkeley


The journal responds, and we respond again

That letter was sent last Monday. This morning, I received a response from the editor-in-chief, Dr Andrew Zalesky, that the authors had revised the correction and that it would be published as soon as possible. As in the previous proposal, the correction includes the statement that FND is “common” but then, in an additional paragraph, notes that ranking diagnoses in order is challenging because different studies yield different rates, depending on quality and methodology. The correction then cites some other research to bolster their claim that FND is “common.” (More on that additional research in a later post.) To me, the authors seem to be trying to absolve themselves of responsibility for making a bogus claim by suggesting that the entire effort to assess prevalence is fraught with issues. That might be true–but this response raises the obvious question of why these experts have spent the last decade making declarative assertions that FND is the #2 diagnosis.

Below is the response I sent to Dr Zalesky:

Dear Dr Zalesky–

Thank you for the response. We very much appreciate the speed with which you and Dr Bonkhoff have addressed this matter. 

The decision by top investigators to repeatedly disseminate untrue information about a seminal study in their field of expertise has led to significant confusion about the actual prevalence rates of FND–not least, undoubtedly, among clinicians who end up seeing and treating some of these patients. We continue to believe that the word “common” on its own is liable to be misunderstood. We also continue to believe that the most appropriate method of correcting this error would be to provide the actual information from the study whose findings were misrepresented. Nonetheless, we appreciate that the authors have acknowledged their error and we accept that the process has now reached its conclusion.  

As suggested by the persistent claim that the Scottish Neurological Symptoms Study (SNSS) found FND to be the #2 presentation at neurology clinics, leading experts at times seem to perceive FND even in the absence of the positive clinical signs that are now required for a diagnosis–or at least they are willing to include such patients in their reported prevalence rates. The phenomenon of interpreting (or misinterpreting) data to maximize apparent prevalence rates of illness has a name in public health and epidemiology. It is called “diagnosis creep.” 

To put this correction in perspective, it is also worth noting another recent reference—an accurate one–to the prevalence of FND found in the SNSS. Professor Jon Stone, a co-author of Perez et al, is also the lead author of Stone et al, the 2010 study from the SNSS cited in Perez et al. In addition, Professor Stone is one of two co-authors of the section about “conversion disorder” on the medical education site UpToDate. (Conversion disorder is the former name for what is now called FND. It is unclear why UpToDate is still using this outdated term.) A note at the bottom of this section indicates it was updated in June of 2022. 

In the epidemiology sub-section, the article states that “the point prevalence of conversion symptoms in clinical settings ranges from 2 to 6 percent.” The section cites three studies, including Stone et al. Here’s what it notes about the latter: “A prospective study of 3781 neurology outpatients found that conversion disorder was present in 6 percent.” This statement is obviously inconsistent with any claim that the study found FND to be the second-most-common presentation, which itself is based on the assertion that the prevalence was 16%.

It remains perplexing that experts in this field, including co-authors of the SNSS, have had no hesitation in tripling that study’s reported prevalence rate by lumping in many other participants who might have had “functional” disorders but did not meet the specific diagnostic criteria for FND—as if the criteria were optional or irrelevant. They clearly know that the SNSS did not in fact find FND to be the #2 diagnosis, as evidenced by the various correct citations of the data. Yet this false claim now peppers the medical literature. 

We hope FND experts take this correction to heart and exercise more caution in citing the SNSS in future papers. The many co-authors of Perez et al, a virtual who’s who of leaders in the field, might also consider initiating similar corrections in every article of theirs that includes the same mis-citation. 

Thank you again. Now that this issue is settled, I plan to blog about it. (I posted the original letter we sent but have refrained from further public comment while the question was being debated.) I will forward the link to any posts that I write.


David Tuller, DrPH
Senior Fellow in Public Health and Journalism
Center for Global Public Health
School of Public Health
University of California, Berkeley


Some further thoughts on this matter…

As noted in my response to Dr Zalesky, we still believe the use of “common” on its own is problematic—it could mean anything to anyone. The authors clearly do not want to be held to the 5.5% figure from the SNSS, even though that is the largest and most authoritative study on the issue. Instead, they prefer to leave the meaning of “common” vague, allowing readers to interpret that how they will. Presumably they believe that the higher rates are more accurate than 5.5%; I assume that’s why they have made this claim repeatedly. But even if that is their belief, it does not warrant the distortion of findings from the SNSS.

It takes an impressive amount of chutzbah to routinely mis-cite data in this way; it is hard to imagine that Berkeley graduate students in my department would get away with such misrepresentation in their dissertations without serious repercussions. It is also perplexing that the entire field of FND has accepted these mis-citations without apparent question. For top medical journals to have published dozens of papers in the last decade with these indisputably untrue claims represents a failure of the peer review process. I hope this situation triggers some soul-searching on the part of authors, peer-reviewers and journal editors about the proper way to cite study findings—although I won’t hold my breath on that score.

23 thoughts on “Trial By Error: FND Experts Agree To Correct Inflated Prevalence Claim”

  1. “For top medical journals to have published dozens of papers in the last decade with these indisputably untrue claims represents a major failure of the peer review process.”

    It looks to me like there could be a lot of correcting to be done. Could this count as an ethical concern? I imagine that many of the journals will be COPE members. Should that organization perhaps be informed so they can alert their member journals about this major failure so they can be more careful going forward?

  2. As told in Osler’s Web, the Center for Disease Control hit upon an amazingly simple strategy to eradicate undeniable evidence.
    Simply broaden the definition and use the “extended CFS version” to say that “Not all people with CFS have those abnormalities, therefore those abnormalities are not CFS”

    They must be “something other than CFS”

    In this way, the prototypes for Holmes Chronic Fatigue Syndrome were taken right out of having the syndrome we started.

  3. If the diagnostic criteria for a medical condition change then it stands to reason that the prevalence rate of that condition will be highly likely to change too. I find it bizarre that anyone would think of supplying prevalence information, as if it’s current, from a study that pre-dated the change to the diagnostic criteria.

  4. I hear you, CT and I find it bizarre that the changes to the diagnostic criteria have been made without discussions with patient groups (eg those with a current PPPD label, who are mostly female) and that there doesn’t seem to be any financial provision made to the NHS (or patients) to cope with the extra demands of these changes. Diagnostic inflation/creep is almost certainly taking place amongst people deemed to be in the FND Subtypes (given Kanaan’s ‘territorial expansion’ commentary, which is, like the FND ‘inclusion’ paper, mostly behind a paywall) and there are plenty of examples of ‘wastebasket’ diagnoses being given to people in the subtypes, as there still are with other types of FND/Conversion Disorder/’MUS’ or whatever they’re calling it on any given day of the week.

    As such, we need complete transparency about the new diagnostic criteria – including detailed information about why patients don’t seem to have been involved in the decision making process – and we need a very simple way to record both misdiagnoses and ‘dustbin’ diagnoses (both for the subtypes and the pre diagnostic criteria change types).

    We also need as much information as possible about the risk factors of developing FND symptoms downstream of taking medications.

    Meanwhile I think it would be interesting to examine the experiences of patients who take the time to put in complaints about the FND dx, given the percentage of patients who were dissatisfied with this dx. So far (as far as I can tell) we only know what neurologists in the UK think about it:

    Hats off to David, as usual, for his perseverance. And hats off to the journal concerned. From the perspective of someone living with a rare condition I hope this will encourage doctors to pause and think twice before slapping DSM labels on people with conditions like Stiff Person Syndrome, Moyamoya Disease and Wilson’s disease.

  5. I firmly believe (on the basis of what I’ve uncovered) that the FND construct (with this apparent repeated hyping of prevalence) is destroying good secondary level healthcare in at least some areas of the UK. I suspect that many things are being ignored/neglected and/or misdiagnosed now because they’re passed off as being FND or ‘functional’ problems – rare diseases, drug side effects and withdrawal effects, unexplained symptoms that need thorough investigation and evaluation, and even well known conditions such as lupus. If hospital bosses are told that FND is common/second most common/represents 16% (or even 30%) of neurology referrals and that they can actually save money in investigations/appointments and length of stay by employing psychologists or psychiatrists to treat these patients then of course their eyes are going to light up. What’s not to like? Nobody wants to deprive patients of healthcare and the 5.5% or so of neurology patients who supposedly have true FND are clearly very unwell and deserve their fair share of health resources. But only their fair share. What’s going on here looks to me like a metaphorical land grab, depriving other patients of the investigations, treatment, services and research that they deserve and I strongly believe that this is already causing immense harm, although it has hardly begun. If this is not stopped in its tracks now, then God help patients referred to secondary care in the UK, no matter what the specialty.

  6. And I ask – what could go wrong IF not only doctors and hospital bosses were being misinformed about prevalence rates, but charities, MPs or government ministers, legal people, research funders/assessors and the general public too?

  7. That is a very welcome move. There is much more than the inaccurate reporting of figures to take issue with from that research. Patients were given their diagnosis by the neurologists at their first appointment and before any investigations were carried out. If a neurologist gave more than one diagnosis, the researchers simply used the first for categorisation purposes without any explanation as to why they adopted this approach. As for the 18-month follow up study, repeatedly cited as evidence for the low misdiagnosis rate of FND, this was based on asking the GP whether there had been any new medical events and if the GP thought the new event was a better explanation for the original symptoms. Only if the GP thought the new event was a better explanation was the original neurologist approached and asked about the consideration of organic cause and follow up testing.* This is a methodology that allows for, and encourages, heuristic anchoring. When the GP made the original referral was there already a psychological bias in the referral note? Why would a neurologist change a diagnosis on the basis of a GP opinion formed in an academic study? And how many GPs thought the new events were a better explanation – because that’s the rate determining step for even breaking into the question of misdiagnosis. At best, the two pieces of research on which many FND claims are predicated, are mere snap shot reportage of unchallenged clinical opinion. No patient was spoken to across this research.

    We definitely need more challenges to the lack lustre research around FND.

    * in the case of 8 deaths the neurologist was re-approached.

  8. Lady Shambles

    That tricky word ‘common’ covers a (literal) multitude of sins, doesn’t it? How it’s interpreted by the average Joe (or Josephine) is more likely to be akin to Princetown University’s list of ‘Common Illnesses’ here:

    Colds and Flu
    Conjunctivitis (“pink eye“)
    Stomach Aches”

    That’s what ‘common’ means to most of us, even the ‘most of us’ who have the misfortune of a niche diagnosis like ME and are more aware of ‘health speak’ than our healthy contemporaries. Of course misusing data and still being able to use the ‘common’ word when negotiating with Health Trusts when you happen to have formed your own vested-interest-coterie for making ‘common’ to mean a great deal more than 5.4% whilst asking for funding to increase your own pot of moolah, that’s a whole other thing. Maybe these dodgy dealings would be better circulated to higher up the food chain.. to those making decisions about how much money is dispensed to certain areas of medicine? After all, if FND is neither ‘common’ nor ‘second most common’ and only makes up 5.4% of neurology referrals and is, by using ‘their own’ data, only 8th down the line, then those making the funding decisions really ought to think again… that’s where the power lies….isn’t it?

  9. Lady Shambles

    As an aside which is purely hypothetical atm…

    As someone who was told, on asking of their supposed (but dyed in the wool / BPS ) ‘Local SFPN Expert’ for a punch biopsy to rule SFPN in or out, that “people like you aren’t positive so we don’t test you”, and on noticing (not just amongst the ME patient population but also amongst the SFPN population) how increasingly difficult it is to get a punch biopsy, I muse on one possible reason for this being to make it harder to hand down a FND diagnosis if the patient sitting in front of you has a positive punch for SFPN in their notes.

    My supposed ‘Local Expert’ tried every reason in the book not to offer me one including magnifying the ‘horribleness’ of the procedure itself. Seriously.. saying that to a woman with two kids and therefore two births behind her is taking mansplaining (or is it just gaslighting) to the ‘nth degree. For the record a SFPN punch is a walk in the park. At least it was for me.

    There doesn’t seem to be any rationale for this procedure being so limited, either on the NHS or, now, privately. It needs to be done properly, but it’s a pretty simple thing to do and KCL histology dept seem more than capable of reading the results. It’s almost as if (this is where my own hypothesis comes into play) the option for a punch biopsy is being deliberately limited.. and to what end? How can that help anyone?
    A patient with a positive result can be assessed for heaps of further tests to understand why that might be the case. I, despite the local expert being (un)able to see my peripheral nerves with his X ray vision, was, and am, positive for SFPN. The local expert had asked me how having a punch biopsy would help me given that there would be no further testing.. I would simply have a ‘result’ with which I could do nothing. Except, in my case, albeit I had to find a private neurologist who would perform the test (given the same ‘Local Expert’ refused to see me via the NHS nor, as per his private consultation, which I’ve described above, did he have the infrastructure to give me the test at all, even though that was the sole reason for my appointment with him… shady or what?), I then had a chest X ray to rule out sarcoid and 43 further blood tests which then led on to another test for a genetic screen for a disease other than ME which proved negative.
    Within those 43 blood tests certain results proved positive and have informed further care (notably outside neurology) which is potentially proving more fruitful. But within neurology, we must assume, given how parsimonious neurology seem to be wrt providing punch biopsies for potential SFPN, there will be some (many?) patients whose diagnosis will be SFPN but who are languishing in the FND cesspit of nothingness because of this reluctance to perform basic testing. After all ‘people like you don’t get it so we don’t test you’ simply doesn’t ‘wash’ from a scientific, or ethical, point of view, does it? Maybe the % of people with SFPN would be considerably bigger than 3rd place?
    This is just one example. Maybe there are other examples of testing in neurology being refused and one could wonder, if that is so, why that might be?
    I refer the reader to my hypothesis ..

  10. Lady Shambles commented:

    “Maybe there are other examples of testing in neurology being refused…”.

    I don’t know about within neurology but in terms of unexplained pain being assessed under a different specialty – pain which, after all, must be neurologically mediated – I do know that testing to determine whether severe pain is local or central has been blocked to a UK patient. Putting these things together, I do wonder – are doctors being taught sadism at med school these days?

  11. PJM commented:
    “I hear you, CT and I find it bizarre that the changes to the diagnostic criteria have been made without discussions with patient groups (eg those with a current PPPD label, who are mostly female)”.

    CRYPTO127 commented:
    “As for the 18-month follow up study, repeatedly cited as evidence for the low misdiagnosis rate of FND, …”

    These two things are linked, I think. One might think that a change to the diagnostic criteria that changes a diagnosis of exclusion into one of inclusion based on positive signs would be a good thing. After all, how can even the best doctor possibly exclude everything when medical science doesn’t know everything? But if you think about it, diagnosis of exclusion means that doctors will hopefully be quite thorough in testing for anything that could possibly be causing those symptoms, while diagnosis by inclusion relies on how good the signs are for correctly detecting FND and for not giving false positive results. David has previously blogged about the reliability of the signs.

    This brings us to the FND misdiagnosis rates which have been claimed to be relatively low. The same things applies here as with my comment above
    “If the diagnostic criteria for a medical condition change then it stands to reason that the prevalence rate of that condition will be highly likely to change too. I find it bizarre that anyone would think of supplying prevalence information, as if it’s current, from a study that pre-dated the change to the diagnostic criteria.”
    If the diagnostic criteria change then it stands to reason that the misdiagnosis rates of that condition will also change, but the misdiagnosis rate that is cited with the 18 month follow-up was from a study that was conducted when diagnosis by exclusion was still very much a thing, when patients were perhaps being protected from misdiagnosis by their doctors being quite diligent about trying to exclude other neurological conditions. Indeed, the focus of the study that the misdiagnosis rate is derived from WAS diagnosis by exclusion. That misdiagnosis rate therefore no longer applies. (NB I recognize that there were issues with that rate anyway – the relatively short follow-up time and how the rate was determined. ) So (mimicking my statement on prevalence rate) – I also find it bizarre that anyone would think of supplying misdiagnosis information, as if it’s current, from a study that pre-dated the change to the diagnostic criteria. Who knows what the misdiagnosis rate is now? I don’t know of any studies that have been done to determine the FND misdiagnosis rate since the changes to the diagnostic criteria/ DSM.

  12. Thank you, CT and CRYPTO127 I appreciate the thought you’ve put into this. As you may be aware, PPPD is not a diagnosis of exclusion and is being over promoted (mention ‘Havana Syndrome’ and up pops Prof Stone, talking about PPPD), over diagnosed and seems to be creating ‘diagnostic overshadowing’ which often seems to happen with so-called ‘functional’ conditions. As with conversion disorder being lumped under FND (possibly without consultation with patients) PPPD is an umbrella diagnosis (of constructs like chronic subjective dizziness, visual vertigo, space/motion discomfort syndrome (a known misdiagnosis for MdDS), ‘phobic’ vertigo etc) which may also contribute to over diagnoses and missed diagnoses of conditions like Binocular Vision Dysfunction (which also has several subtypes), MdDS and Vestibular Migraine. So it’s all a bit of a mess and the collateral damage/iatrogenic harm vs tangible benefits to patients of the ‘territorial expansion/claim’ has yet to be measured.

    I’ve been reminded that I should have added Myositis and Vasculitis to the list of conditions which can be misdiagnosed, all too easily, as FNDs. I should also add that my (UK) neurologist thinks that Functional Cognitive Disorders are being over diagnosed while I think that cognitive/vestibular interactions are often missed and/or misdiagnosed as FCDs. But getting those misdiagnoses recorded is, as usual, fraught with difficulty and once they are in our electronic records, they tend to stay there.

    Meanwhile stats are one thing (and I am not good with numbers at the best of times, so I am very glad David and others are) but language is important too. With ‘functional’ they’ve already taken a really useful word and twisted it out of all recognition (although we know it still means ‘hysterical’ or did when ‘the function of ‘functional’ a mixed methods review’ was published). But recently Prof Stone has taken it one step further in that he now thinks that the opposite of ‘functional’ is ‘structural’ (see YouTube Jon Stone Organic vs Functional: perspectives from Neurology ffi) which it isn’t. And unless patients with a FND dx agree with him regarding this antonym (I’m not sure any were present at that event) this is likely to cause even more confusion when it comes to making and upholding this dx.

  13. Thanks PJM for your insight into the area of PPPD. What gets me is that some FND ‘experts’/proponents appear to blame other practitioners for getting diagnosis wrong when I imagine they are only going by what they’ve been told/taught by FND experts. It all strikes me as a terrible mess which urgently needs cleaning up. Many thanks to David for getting stuck in.

  14. Great post and great comments everyone. I got a kick out of ‘Lady Shambles’ who used ‘health speak’ as an apt description for the syndrome being complained of. This description, as David and the astute commentators allude to, is a way of pointing out the “It wouldn’t do to say …” syndrome that plagues all societies that wander into the authoritarian wilderness. Even as a significant portion of our populace faces “the worst” (The Third Pole Water Line – 2). Please keep up the much needed good work.

  15. I liked Lady Shambles’ comments too. I particularly enjoyed “Seriously.. saying that to a woman with two kids and therefore two births behind her is taking mansplaining (or is it just gaslighting) to the ‘nth degree. For the record a SFPN punch is a walk in the park. At least it was for me.”

    In my experience, male doctors (not all, and not exclusively male ones) quite frequently talk down to women in a way that suggests that they’re hypochondriac wimps. If the women haven’t experienced the pain of childbirth then there’s a fair chance that they may suffer the crippling and crumpling pain of endometriosis. It’s common, you know, well more common among women (about 1 in 10) than FND is among neurology patients (about 1 in 17 or so).

  16. Mike Fraumeni

    Great work David and with your colleagues as usual. Excellent comments here as usual. I’m in a happy place after having my CD/FND diagnosis overturned by a wonderful and very experienced neurologist this past weekend who after his examination said definitely not CD/FND but rather a dual organic diagnosis of a rare dystonic disease named Paroxysmal Kinesigenic Choreoathetosis (Dystonia 10) combined with parkinsonism and I started on Sinemet (levodopa/cardidopa) today for the parkinsonian tremor. Below are a few references from Pubmed, PMID linkage, for anyone interested in how this disease can be mistaken for a psychogenic/conversion illness. Again thank-you David for your work.

  17. Great to see you here, Mike and I am glad you are in a happy place 🙂 I saw some of your comments on an earlier blog too and am very grateful for all the links you’ve provided.

    CT – the situation with PPPD is, erm, complicated (like many things FND) but to me it looked a bit dodgy from the start, not least because the dx criteria included a citation about ‘phrenology and mental derangement’ from 1831 which is over 400 pages long and almost completely incomprehensible. Apparently it refers to the ‘structural vs functional debate’ which should have been over years ago since we do not need to have structural changes to get symptoms of, for example, migraine or motion sickness. Plus there are ‘red flags for when it’s not PPPD’ but these are not being circulated widely by the professional content providers (eg Profs Stone and Staab). However the ‘territorial expansion’ commentary which accompanied the subtypes paper seems to be all about people deemed to be in the subtypes becoming the poster people for FND but I’m not seeing that happen, despite the ‘sheer folly’ of Stone having PPPD on his site for over a decade. That last sentence (the rest is behind a paywall) is certainly debatable, given the testimonies from FND Portal etc but open debate with the FND Society may be some way off, if my experience and that of the people who have shown that FND symptoms can occur downstream from taking antidepressants. When the PPPD criteria were published several fb comments rang true with me including ‘PPPD is the new fibro’ and ‘I dodged that bullet’ and when Prof Kaski published something about it a tweet from Prof O’Leary ‘FND ed is terribly reckless, so practice is reckless’ also rang true. I thought her response to the FND is a feminist issue paper was excellent and in hindsight I was too generous in mine.

    What is interesting me now is the FND chronic pain overlap paper that David kindly included in this blog. They are using electronic records and, as far as I can tell, selecting participants based on a lifetime dx of FND. So it’s possible that even if someone has had their FND dx quashed (eg the daughter of someone in the PPPD and Life group, or Mike) they could still be recruited for this trial. Possibly without their knowledge or consent.

  18. Mike Fraumeni

    Interesting PJM, very interesting. After first dose of Sinemet, a dramatic improvement in the tremor in hands and feet, able to touch my nose with my finger now without any tremor. Extending legs and feet not tremoring hardly, a bit but huge improvement. One step at a time, no cure for parkinsonism but so relieved to have something to help now.

  19. PJM – Thanks, I’ll check out that link later. Have you come across this - – before? I’m not necessarily agreeing with it but thought you might find it interesting.

  20. Ah drat, my comment should have read ‘if my experience … is anything to go by’ (this is what happens when I post when short of spoons). I’m not on twitter but one of my contacts (a retired doctor) is and when the FND subtypes paper was published she kindly sent me this tweet from Prof Escamez: ‘Please, explore patients with dizziness before labelling them with PPPD. Many of them have a vestibular disorder’. True dat.

    And after yet another paper about PPPD got published one of the UK researchers tweeted this ‘an imperfect or broad term is more clear and useful than none, so long as people understand it as such and are working to refine it.’ However I am not convinced that this is being conveyed to patients or their doctors. I am aware that some surgically trained ENTs give the PPPD dx to avoid further contact with their patients and I’m not OK with that since they then can’t figure out what medications they should/shouldn’t take or how to wean off them successfully. Prof Stone tells his patients with vestibular migraine that PPPD symptoms are the brain’s response to the migraine and can be made worse in ‘fake’ environments like supermarkets yet other providers say their patients with VM don’t get pppd symptoms so – in some cases, at least – they could be the result of poorly managed migraine. Profs Staab and Stone (and some of the Stone clones) both believe that everyone with MdDS has FND/MUS even though many of us wouldn’t meet the criteria for inclusion in DSM, either when we’re in remission (for those of us lucky enough to get remission) or in episode. Why they feel the need to land grab an entire patient population – who are mostly women – and shove us under the ‘functional’/DSM brolly is an interesting reflection of their mindsets.

    CT – Tim Hain is a longstanding pal 🙂 We sometimes disagree with each other but we’re both OK with that. He is aware of the, erm, issues about the over diagnosis of PPPD and how it’s conceptualised. The last ENT I spoke to about it said he wouldn’t diagnose it unless he had to because ‘it could stop other doctors from looking for other things’ so it’s clear that there is diagnostic overshadowing (all too common with ‘functional’ conditions) as well as diagnostic creep/inflation. One of my contacts who runs the Audio Vestibular Medicine International Board thinks that patients should reject the pppd label and I’m inclined to agree with him.

    Mike – that’s very interesting and I am delighted you’re getting some relief 🙂 I trialled Sinemet for tremors but am aware that it wasn’t tested on women during the development phase. Unfortunately I got much worse cog fog from it and my left leg forgot it belonged to me. Had a FND neurologist done the Hoover’s test on me when I was taking it, I’d probably have received a double FND label. Or triple if we factor in the cog fog being misdiagnosed as ‘functional cognitive disorder’. Thanks again for the links 🙂

  21. Mike Fraumeni

    PJM, Sorry to hear that Sinemet didn’t work for you. For me, so far, a game changer, I have my life back and I can now walk and count backwards and keep walking without going to the ground on one knee. Also my delusional friend “Dave” is gone and also able to touch my nose with eyes closed and remain standing with eyes closed for a bit, before couldn’t do that at all. But yes, it’s not for everyone as everyone’s depending on so many factors and as you mention gender as an issue. The parkinsonism side of my paroxysmal kinesigenic dyskinesia is most likely unique to this disease as it is unique from individual to individual. But there is some evidence that it can help cognition with certain parkinsonism:

    “Can levodopa prevent cognitive decline in patients with Parkinson’s disease?” (2017)
    “The present study suggests that levodopa might prevent a decline in cognitive function in non-demented patients with PD. This finding is consistent with the results of previous studies providing evidence that levodopa has a positive effect on cognitive impairment [12-16]. Levodopa improved the neuropsychiatric scores for verbal attention and memory deterioration in patients with PD who had or did not have dementia [12]. Learning performance was improved in association with learning-related activation responses in the occipital association cortex on PET imaging in non-demented patients with PD [13]. Levodopa ameliorates cognitive deficits in PD with blood flow changes in the right dorsolateral prefrontal cortex [14]. Chronic dopaminergic replacement therapy with levodopa is associated with significant cognitive improvements in learning and long-term verbal and visual memory, visuospatial abilities, and frontal-lobe functioning [15]. Continuous duodenal infusion of levodopa improved the marked cognitive impairment and increased the MMSE score by three or six points in two patients with PD [16].”

  22. 4 months ago a member of the FND HU Hub wrote this and has given me permission to reproduce it here. As far as we know it’s an isolated incident but as the OP said (regarding conversion disorder) ‘One misdiagnosis is one too many’ and we don’t know if this issue has been resolved.


    If you live in UK and have FND you may wish to check your online medical record has not been incorrectly updated.

    I have had FND for over 12 years following a virus. When I was diagnosed 10 years ago, my consultant neurologist wrote a clear diagnosis letter, stating that I have a physical illness. I recently went to check something on my online medical record, and noticed that they had added “Conversion Disorder (psychological)” to the summary of my conditions. I emailed and asked them to change it to my actual diagnosis, and could see they had changed it to ” Psychogenic Conservation Disorder “. I have never been diagnosed with Conversion Disorder.

    I have just had a long conversation with the practice manager at my surgery. It transpires that something insidious is afoot; a GP did not update my medical record, a computer did! Apparently the coding for conditions has been updated on the computer system, and it had modified all cases of FND to Psychogenic Conservation Disorder. When she tried to update it manually it changed it back and gave the message “the preferred term for FND is Psychogenic Conservation Disorder “. When I explained that whilst Conservation Disorder is a Functional Neurological Disorder, not all Functional Neurological Disorders are Conservation Disorder, she found a way of tricking it into saying FND, but she said I should check it regularly because she isn’t confident it won’t happen again.

    I hope nobody else is impacted, but felt it best to warn you all just in case.

    Best wishes

  23. I strongly contend that the term ‘conversion disorder’ and all its synonyms need to go and go for good. It seemingly had new life breathed into it through this 2005 paper - by Stone, Warlow, Carson and Sharpe (in conjunction with this paper - by the same authors and 3 others) after Eliot Slater had driven the nails into hysteria’s coffin several decades before. FND is commonly used as yet another synonym for conversion disorder, apparently arrived at, or at least helped along, by Stone and his colleagues who conducted a study to find out what term would be least likely to offend patients - . That paper’s by the same 4 authors (with 4 others), so I assume it has the same agenda. If a causation link to a psychological stressor cannot be made in 20% to 70% of FND patients (- then shouldn’t the conversion theory be scrapped? To my mind, FND ‘experts’ should clearly admit that the conversion theory is wrong and no longer stands up, and should stop bringing up ‘conversion disorder’ in paper after paper like it’s some sort of nod-and-a-wink to their fellow doctors.

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