Recent progress in understanding how to diagnose FND ~ Written by Dr Tim Nicholson

FND Action’s awareness day was an important and sorely needed initiative; for the public, and indeed many clinicians, FND remains something of a mystery and many important misunderstandings exist. Thankfully there has been significant progress in our understanding over recent years and this has been reflected in important changes to the way in which FND is diagnosed, in terms of what particular the features of the disorder need to be identified to make an official diagnosis.

Perhaps the biggest, and most unhelpful, misunderstandings are that FND is somehow under a patient’s control and that there is always a psychological trauma that has caused the symptoms. Understandably these can be deeply hurtful if either said or implied to patients, and often result in healthcare professionals (and sometimes also relatives and friends) treating them differently and less sympathetically than they would other conditions. This is because these misunderstandings can lead them to think the symptoms are ‘put on’ (i.e. feigned) or that the symptoms are ‘all in their head’, not real or, worse still, that they are ‘mad’.

FND symptoms can, due to features such as higher levels of variability than seen in other conditions and improvement with distraction, look similar to consciously generated (i.e. ‘feigned’ symptoms), especially to those not familiar with these conditions. However, clinicians familiar with FND are aware that this is clearly not the case. Thankfully the latest version of the official diagnostic criteria (‘DSM5’) have removed the need to exclude feigning in order to make the diagnosis – a previous requirement that was not necessary and fuelled the worry in the minds of clinicians that the symptoms were feigned.

With regard to traumas occurring either in the past (e.g. childhood abuse) or at the time when the symptoms start, it is now definitely established that for a significant proportion of patients such traumas can’t be found. It is also important for clinicians to realise that even if they are found, such traumas are actually quite common in the general population and therefore they may just be ‘coincidental’ and might not be related to the disorder. However, there remains a significant group of patients for whom it is clear that such traumas are relevant or whose symptoms are clearly related to stress, and this is potentially relevant to their treatment. Studies have recently been done that look very thoroughly for stressors around the time of onset in FND and approximately 10% have no identifiable stressor, even in a population of patients referred to psychiatrists.

These findings challenge the historical (‘Freudian’) models of the disorder that traumas occurring in the past (e.g. childhood abuse) or around the time the symptoms will always be found, and that they are the only cause of the disorder.

DSM5 has accordingly dropped the need for identifying such a trauma – something that used to be essential to find. This explains why clinicians who are not aware of this change, feel the need to unearth a trauma and if it isn’t found it can be misconstrued that the patient isn’t able to remember it or, worse still, deliberately not revealing it. However, as there are patients for whom such traumas are relevant, or whose symptoms are clearly related to stress, it remains important to sensitively enquire about such issues – but critically not assuming they must exist.

The final important change to the diagnostic criteria is that it is now essential to identify ‘positive neurological features’ that are not found in neurological diseases, such as stroke or MS, and are therefore unique to FND. Such features include Hoover’s sign in functional weakness, where a patient’s reflex leg movement is stronger than when trying to initiate it themselves, and that functional tremors are distractible, i.e. improve when the patient’s attention is focused away from the tremor. So, this new criterion has been added and therefore replaces the need for the identification of stressors.  Another key development has been that such positive features should now be explained to patients as this helps them understand why the doctors know their symptoms aren’t due to another disorder and also shows the potential for recovery.

Another key change has been the addition of FND as an official term and it has clearly become the preferred term of patients, and is also steadily becoming the preferred term of clinicians.

So, there has been major progress with the way we diagnose the disorder and communicate with patients. However there is still much to be done – not least in making non-specialist clinicians and the wider public aware of these important changes.


Dr Tim Nicholson is a consultant neuropsychiatrist at the Maudsley & King’s College Hospitals and a lecturer at the Institute of Psychiatry, Psychology & Neuroscience, King’s College London.