יום חמישי, 2 באוקטובר 2014

Functional neurological disorder

As more than once, I have encountered this "diagnosis" as an ultimate explanation for at times life-endangering symptoms, I decided to try and understand where it stems from and what is its utility in the management of neurological diseases. This is at least my opinion:


A diagnosis based on ignorance and deception.

The Diagnostic and statistical manual of psychiatry (DSM-5) has a relatively new psychiatric entity-"functional neurological symptom disorder". In order to make this diagnosis it is enough that: 1.The patient suffers from disabling neurological symptoms. 2. The physician taking care of the patient (or the entire field of neurology) has no explanation for the patient's symptoms or those are inconsistent with the current knowledge and understanding. Even a patient with a known illness can have a functional disorder as well, if he/she has an unusual presentation or less common symptoms that do not fit with the knowledge and understanding of his or her physician regarding that illness. (Stone et al., 2012)

This is the only diagnosis I am aware of, which is based entirely on the inability of a physician or an entire field to find a reasonable explanation for a certain ailment or symptom. Had we taken this approach in medicine in general we would be left with very little knowledge and ability to treat numerous disease, which were all initially unexplained and required careful clinical observation and thought process of numerous physicians before they were understood. We would also dismiss numerous patients who have less common presentations of known diseases or ignore significant symptoms which are less typical, but caused by a serious underlying disorder or response to a commonly used treatment.

Unless there are major advances in the field of neurology up to 30% of patients attending neurological clinics around the world are going to satisfy those criteria1 and even more if patients with functional symptoms in addition to a known neurological illness are taken into account. This entity is no more than a disguise for the old term coined by Charcot and Freud-"Hysteria". Yet, as the presumed pathogenesis of this disorder has been seriously questioned,  emotional symptoms, behavioral abnormalities or personality traits are no longer required for this diagnosis in the DSM-52. Furthermore, this vague and ambiguous term, deliberately chosen to be more acceptable to patients, creates an atmosphere of deceit, even if unintentionally3.  

Numerous papers, case reports and books4-5 have warned against the use of this diagnosis. Eliot Slater has been repeatedly cited for his highly influential study in 19651 "The diagnosis of hysteria is a disguise for ignorance and a fertile source for clinical error. It is in fact not only a delusion but also a snare" But also others, 20 years later were aware of its pitfalls.  "Its dismissive potential coupled with its negative sociocultural connotations from which physicians are not exempt…offers an expedient solution for a diagnostically confusing patient and provides a release of negative emotions or even punitive actions under the guise of a respectful medical label"4. and "Hysteria lends itself most readily to the needs of physicians who have their concepts challenged and thus need to dismiss the "problem patient" for emotional needs of their own… sometimes with horrific results"

This diagnosis of a "functional disorder" indeed satisfies the emotional needs of physicians while encouraging ignorance and dismissal of at times seriously ill patients, as well as lack of curiosity to understand the currently unexplained.

 The deceptive nature of this diagnosis undermines the foundations of the physician-patient relationship which must be based on mutual trust and respect. It is ill-defined and therefore prone to numerous errors which could seriously endanger patient's well beings and lives. Even in patients with a known neurological illness, attributing significant symptoms to this entity can lead to underestimation of the severity of the illness, inadequate or partial treatment or inadequate assessment of response to treatment as well as ignoring significant side-effects of that treatment.

Even when an empathic relationship is created, there can be dire consequences to this approach if it leads to an illusion of adequate treatment for physician and patient alike. Just like in any other disease, empathy, dedication and care should come with and not instead of adequate medical treatment. Based, on this and my personal experience with quite a few patients with “functional symptoms” that upon more elaborate evaluation had numerous conditions such as a rare presentation of leukemia, a rare response to a commonly used medication and a rare presentation of myasthenia, I think that the medical community should seriously question the validity of this diagnosis.

I think it is OK to admit to ourselves and our patients that with all the significant advances in medicine there is still much that we do not know and need to study and learn, without creating a diagnosis or explanation for symptoms which in the long term create more harm than good for patients and the medical community alike.



1           Stone, J., Hewett, R., Carson, A., Warlow, C., and Sharpe, M., The 'disappearance' of hysteria: historical mystery or illusion?, J R Soc Med 101 (1), 12, (2008).
2           Stone, J., LaFrance, W. C., Jr., Brown, R., Spiegel, D., Levenson, J. L., and Sharpe, M., Conversion disorder: current problems and potential solutions for DSM-5, J Psychosom Res 71 (6), 369.
3           Kanaan, R. A., Armstrong, D., and Wessely, S. C., The function of 'functional': a mixed methods investigation, J Neurol Neurosurg Psychiatry 83 (3), 248.
4           Kutz, I., Garb, R., and Kuritzky, A., Diagnosis of misdiagnosis: on some of the origins and functions of psychophysical misdiagnosis, Gen Hosp Psychiatry 5 (3), 197, (1983).
5           Chloe G, K. A., My Imaginary illness: a journey into uncertainty and prejudice in medical diagnosis. (Cornell university press, Ithaca and London, 2010).
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