But an estimated
4 to 12 out of 100,000 people develop FND, and it’s
the second most common presentation in neurology clinics worldwide.
Now that is about 1 in 10,000 people with FND (could be about right). But MS is about 1 in 1000 and headache about 1 in 1, of which maybe 1 in 10 see a neurologist, and peripheral neuropathy is about 1 in 20. So how does FND come to be the second most common...
It seems to be a
common claim. Two examples:
Functional Neurological Disorder: Historical Trends and Urgent Directions, 2023, Journal of Neurology Research (
Link)
The worldwide distribution of FND has been rapidly increasing. The incidence rate of FND between 1976 and 2010 was 4 to 12 per 100,000 patients per year [
21,
47-
49] and the prevalence was 50 per 100,000 population [
50].
In 2010, FND was found to be the second most common reason for new outpatient neurological evaluation [
51].
Seminars in General Adult Psychiatry, p.369, 2024 (
Link)
It is commonly stated that FND is the second most common disorder in neurology outpatient clinics, echoing the prescient observations of Sydenham. although this may only be strictly true when a broad view of functional symptoms is taken.25,26 FND is certainly common in emergency departments, particularly when presenting in similar fashion to acute stroke, cauda equina syndrome or epileptic seizure.27 There are some estimates that suggest that 1 in 10 acute neurology admissions are for FND. 28 Despite these often acute presentations, it is not infrequent for patients to wait several years after the onset of their symptoms to receive a diagnosis of FND.20
Of the studies I looked at, they all seem to cite the same study:
Who is referred to neurology clinics?--the diagnoses made in 3781 new patients, 2010
J Stone, A Carson, R Duncan, R Roberts, C Warlow, C Hibberd, R Coleman, R Cull, G Murray, A Pelosi, J Cavanagh, K Matthews, R Goldbeck, R Smyth, J Walker, M Sharpe
Objective
Information on the nature and relative frequency of diagnoses made in referrals to neurology outpatient clinics is an important guide to priorities in services, teaching and research. Previous studies of this topic have been limited by being of only single centres or lacking in detail. We aimed to describe the neurological diagnoses made in a large series of referrals to neurology outpatient clinics.
Method
Newly referred outpatients attending neurology clinics in all the NHS neurological centres in Scotland, UK were recruited over a period of 15 months. The assessing neurologists recorded the initial diagnosis they made. An additional rating of the degree to which the neurologist considered the patient's symptoms to be explained by disease was used to categorise those diagnoses that simply described a symptom such as 'fatigue'.
Results
Three thousand seven hundred and eighty-one patients participated (91% of those eligible). The commonest categories of diagnosis made were: headache (19%), functional and psychological symptoms (16%), epilepsy (14%), peripheral nerve disorders (11%), miscellaneous neurological disorders (10%), demyelination (7%), spinal disorders (6%), Parkinson's disease/movement disorders (6%), and syncope (4%). Detailed breakdowns of each category are provided.
Conclusions
Headache, functional/psychological disorders and epilepsy are the most common diagnoses in new patient referral to neurological services. This information should be used to shape priorities for services, teaching and research.
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