Functional Neurological Symptom Disorder (FND)
Functional Neurological Symptom disorder (FND) is caused not by changes in the structure of the brain but by changes in how brain networks work.
Functional Neurological Symptom Disorder (FND) is defined as altered motor or sensory function that is incompatible with neurological/medical conditions, is not better explained by another medical/mental disorder and is associated with clinically significant distress or impairment In social, occupational or other areas of functioning [as per the Diagnostic and statistical manual of mental disorders, Fifth Edition, Text Revision (DSM-5-TR™)].
FND is also called “Conversion Disorder” as early theorists speculated that psychological issues (conflicts), were “converted” to neurologic symptoms (Ruiz, Pedro; Verduin, Marcia. Kaplan & Sadock’s Synopsis of Psychiatry). These symptoms serve the “function” of keeping internal psychological conflict outside of conscious awareness (primary gain). These symptoms indirectly may yield tangible benefits/advantages for the patient (secondary gain). The psychological stressor(s) may or may not be identifiable to the clinician, to the patient or to others around them. The experience of symptoms is considered to be genuine, not “faked.”
There are a wide range of signs/symptoms, some of which may be tremors, paralysis, weakness, psychogenic non-epileptiform seizures, hemianesthesia with a precise midline demarcation, blindness, light sensitivity, deafness, and tinnitus.
At times, some symptoms may be incorrectly identified as FND. Aa an example, if an individual feels they have a hard time staying awake, this may be due to depression, anxiety, narcolepsy or chronic fatigue syndrome. This is not FND, if there is no overt motor or sensory impairment noted. If an individual is beginning to find it hard to remember things, this may be due to depression (“pseudodementia”), anxiety, dementia, mild neurocognitive disorder, ADHD or dissociative disorder. This is not FND if there is no overt motor or sensory impairment noted.
Other (non-FND) ways to understand individuals with somatic symptoms and complaints may include Somatic Symptom Disorder (somatic symptoms associated with excessive thoughts, feelings and/or behaviors related to the symptoms), Illness Anxiety Disorder (heightened anxiety about one’s health, absent or mild symptoms), or intentional symptom production.
At times the term Functional Cognitive Disorder (a non-DSM-5-TRTM term) is used to describe cognitive decline/difficulties.This is not Functional Neurological Symptom Disorder (FND) as cognitive impairment falls outside of the DSM - 5-TRTM criteria for FND. Functional Cognitive Disorder is at times used to describe clinical features that may be better characterized by Mild Neurocognitive Disorder (a DSM - 5-TRTMDiagnosis). A Mild Neurocognitive Disorder is defined as a “modest” decline in cognitive functioning such as attention, memory, language and social functioning.
At times, medical/neurological conditions may be incorrectly diagnosed as FND. Some examples of these disorders include: seizure disorders, autonomic conditions (postural orthostatic tachycardia syndrome), chronic pain conditions (fibromyalgia, myofascial pain syndrome, and complex regional pain syndrome),autoimmune conditions (Sjögren’s syndrome, SLE), post-treatment Lyme disease, Long COVID, and genetic conditions, (hypermobility spectrum disorders, Fabry’s disease), to name a few.
The diagnosis of FND should only be made after a careful review and consideration of the diagnostic features. This process will usually involve assessments by a family physician, neurologist and psychiatrist but may also include other specialists depending on the nature of the clinical symptoms.
Treatment approaches and plans for FND are tailored to the nature of the symptoms and include a multidisciplinary approach of including psychotherapy (cognitive-behavioral therapy and/or psychodynamic psychotherapy), occupational therapy (to improve return of functioning), physiotherapy (for motor retraining if needed) and medication treatment for associated disorders that may influence recovery (such as depression, anxiety or ADHD).
Patients may ask “Are you saying it’s all in my head?” and the answer is No. The patient’s symptoms are real and not imagined. That is why treatment involves psychological support as well as support for the specific symptoms that have been described.
