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FND is a problem with how the brain and body send and receive signals.

What is FND

What is Functional Neurological Disorder?

Functional Neurological Disorder (FND) is a problem with the functioning of the nervous system and how the brain and body send and receive signals. Functional Neurological Disorders are considered to be multifactorial, which means many different risk factors can contribute to the development of the disorder. Physical and/or psychological risk factors can cause functional symptoms which include a variety of physical, sensory and cognitive symptoms that have yet to be explained by a recognized disease. The symptoms are real and can cause impairment in quality of life that is similar to and in some aspects worse than other neurological conditions. FND occupies a grey area between psychiatry and neurology that historically has failed to gain the interest of researchers and clinicians. The prevalence and potential reversibility of functional illness have peaked new research interests. New scientific findings are influencing how patients are diagnosed, treated, and creating an overall change in attitude toward Functional Neurological Disorder patients.

How common is Functional Neurological Disorder?

Although FND is listed as a rare disease, researchers are finding that functional symptoms are often seen in neurological services making it a common disorder. One report indicates approximately 1/3 of outpatient neurology clinic attendances are patients reporting functional symptoms. While the exact prevalence is unknown, FND is the second most common reason for a neurological outpatient visit after headache/migraine. The mechanisms which cause FND continues to be poorly understood despite its prevalence within neurological clinics.

What are Functional Neurological Disorder symptoms?

The most common misconception is that FND patients are in control of some or all of their symptoms. The patient does not consciously produce functional symptoms. Functional Neurological Disorder symptoms are often described as appearing suddenly and progressing rapidly. Symptoms typically wax and wane, including complete remissions and sudden recurrences. It is common for other illness or physical injury to trigger functional symptoms or for patients to develop functional overlay with concurrent illnesses. The co-occurrence of functional symptoms should not impede the care and treatment of the underlying illness.

How to diagnose Functional Neurological Disorder?

The diagnosis of FND should be approached in the same transparent and straightforward way a physician would do for other patient and diagnosis seen in their clinic.  An FND diagnosis should be made from a detailed patient history and positive signs. Any doctor, usually a neurologist, that makes the diagnosis of a functional symptom should be very familiar both with the possible neurological diagnoses that those symptoms could represent and also with the positive clinical features of Functional Neurological Disorder.

What is the treatment for Functional Neurological Disorder?

The most important first step toward a successful treatment for Functional Neurological Disorder comes from clear and effective communication in a mutually respectable environment. The clinician’s ability to explain the diagnosis and educate the patient is of critical importance to the subsequent likelihood of successful treatment. Evidence is now emerging for the utility of multidisciplinary treatment, especially specific physical therapy (for motor symptoms) and psychotherapy (for attacks or seizures).

What causes Functional Neurological Disorder?

Despite the prevalence of Functional Neurological Disorder, the exact cause of FND is unknown. Many different predisposing factors likely make patients more susceptible to functional symptoms, and at the time of illness onset, these precipitating factors may likely trigger or exacerbate FND symptoms which then cultivate on-going functional symptoms. Perpetuating factors likely begin to create new neuropathways, which could eventually cause changes in the brain. These neuropathways can be retrained with proper treatment and care.

In the most recent fMRI studies, patients with FND showed decreased functional connectivity in some parts of the brain compared to their healthy counterparts. While these findings do not identify the predisposing factors to functional symptoms, they suggest a decrease in function between voluntary motor pathways and self-agency. An impairment of self-agency or the sense that one is not in control of voluntary movement is a defining characteristic of FND. These findings play a critical role in how patient symptoms are understood. Given the physiological evidence that functional movements are voluntary in nature, medical professionals often mistake patients as feigning or malingering. The resting-state fMRI’s lend itself to support an organic abnormality of functional connectivity in the brains of FND patients. These results are consistent with FND patient exams and symptom reports.

Historically, FND has traditionally been viewed as an entirely psychological disorder resulting in physical symptoms caused by suppressed trauma. Psychological disorders and stressful life events, both recent and in childhood, may be risk factors for developing the condition in some patients, but they rarely provide a full explanation for the cause of the condition and are absent in many patients. Patients do not have to be stressed, depressed or anxious to develop functional symptoms, nor had they had to have had an adverse childhood experience. Patients, physicians, and psychologists often fall into old paradigm traps searching relentlessly for underlying trauma that does not exist. It can be essential to address the possibility of psychological contributing factors for all patients. However, this approach should not negate the possible need and effectiveness of other treatment options.


The habitual change in terminology has resulted in a great deal of confusion, stigma, and frustration surrounding FND. While the individual labels have different meanings, they are all terms used for the same set of symptoms. Here are the most common:

  • Functional Neurological Disorder encompasses all symptoms which are found to be functional.
  • Functional Movement Disorder refers specifically to those symptoms that are movement-related. 
  • Conversion Disorder is a term that is relatable to some patients who can clearly define a psychological trauma, which they are “converting” to their physical symptom. Because many patients do not have an identifiable psychological trauma, the Conversion Disorder label is not a one size fits all.
  • Dissociative Neurological Symptom Disorder the most recent term used in the ICD-11 (World Health Organization International Coding manual) despite pushback from FND Hope and leading FND specialists around the world. 


FND Hope International advocates for all patients with functional symptoms regardless of the diagnostic label used or reason the individual is symptomatic.

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