Conversion disorder

Functional neurological symptom disorder (FNsD or FND), previously known as conversion disorder, is characterized by neurological symptoms—such as motor or sensory dysfunction—that are not explained by a medical or neurological condition. These symptoms are not under voluntary control and are not intentionally produced. The condition is often triggered by a severe emotional or mental crisis that “converts” to a physical problem. For example, a person who witnesses a traumatic accident may suddenly become blind. The condition does not involve structural damage—for instance, there may be no actual damage to the eyes—but the psychological stress of what happened is so great that it causes the nerves to react as if there is some physical problem, resulting in symptoms similar to those present with physical damage. FNsD is treatable; the prognosis depends on the person and their physical and mental state before the disorder emerged.

Background

The American Psychiatric Association’s 2022 Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition Text Revision (DSM-5-TR) changed the name of this condition from “Conversion Disorder (Functional Neurological Symptom Disorder)” to “Functional Neurological Symptom Disorder (Conversion Disorder),” reversing the parenthetical order of the terms as part of a broader shift toward clinically relevant, internationally recognized, and less stigmatizing language.

The symptoms of FNsD vary depending on the area of the body that is affected. In general, the person will have a physical health problem that affects one of the senses (sight, hearing, taste, smell, or touch) or the movement of one or more body parts. Such problems can include paralysis, blindness, or other symptoms such as uncontrolled movements, diarrhea, numbness in a hand or foot, an inability to speak, or any other physical malfunction with no discernible physical cause.

Most of the time, symptom onset is sudden and can eventually be traced to some traumatic or upsetting experience. This experience need not be recent, as FNsD can be triggered by remembering a past event. For instance, an adult who was molested as a child may hear a news story about another child’s molestation and develop a facial tic or numbness when they recall their own helplessness.

Sometimes, a person will be affected by a more intermittent form of FNsD. For example, a person who is afraid of public speaking may experience severe stomach cramps and diarrhea whenever a speech must be made but appear fine afterward. The stomach problems are not brought on by any physical problem, such as a virus or food poisoning, but rather by stress that the body has converted to a physical symptom.

One of the major signs that a physical problem is the result of FNsD is its sudden onset. For instance, it is likely to be FNsD if someone who is going skydiving suddenly develops numbness in both legs after witnessing another skydiver have a rough landing. In this case, the mind is attempting to protect the person from experiencing the rough landing that is now feared. Other signs of FNsD include a history of a psychological problem that resolves once the physical symptom appears to prevent the person from facing the source of the fear or stress and a lack of concern or even a feeling of relief that the symptom has occurred, such as the would-be skydiver seeming unconcerned about their leg numbness.

The diagnostic criteria for FNsD also changed in the DSM-5-TR—identifying a psychological cause is no longer required, and a psychological stressor does not have to be present to diagnose FNsD. FNsD is diagnosed based on neurological symptoms that are incompatible with recognized medical or neurological conditions, and that are internally inconsistent on clinical examination. It does not require identifying a psychological cause or ruling out every possible medical explanation.

Overview

Although patients with FNsD do not have structural damage causing their symptoms, it is not appropriate to say the problem is “all in their head” or that the condition is not real. The stress or shock the person has experienced affects how the brain processes signals, leading to symptoms that resemble those of neurological conditions without structural damage. The person does not have conscious control over this and cannot will it to stop.

Some cases of FNsD resolve as spontaneously as they began. This can happen when the person realizes or is helped to realize that the source of stress or fear is not as intimidating as it once seemed. For example, a person who is very intimidated by meeting an expert in their field may suddenly become unable to speak. If the person subsequently hears the expert make a mistake, however, the person may realize that the expert is not as formidable as once thought and recover the ability to speak. Other people may find that their symptoms resolve after performing an activity they were afraid of several times. For example, a person fearful of public speaking may not experience stomach upset anymore after giving several speeches. Sometimes, merely assuring the person that the health condition is not serious will be enough to resolve the problem.

In other cases, individuals may need more help to recover from FNsD. This might involve counseling and/or behavioral training to help in dealing with the disorder trigger, physical therapy to help retrain the body part to respond to normal nerve impulses, and treatment for stress. Physicians may also attempt transcranial magnetic stimulation (TMS), a procedure that uses a magnetic fields to influence brain activity, although its use in FNsD remains under investigation.

The outcome for most people with FNsD is good. The condition is not usually life-threatening, but it does affect a person’s quality of life. As noted, some cases will resolve spontaneously, while others will gradually improve and disappear in a few days or weeks. Multidisciplinary treatment includes physical therapy, cognitive behavioral therapy (CBT), and education about the condition. Educating individuals about the nature of FND can itself lead to symptom improvement.

Some factors that can prolong a bout of FNsD include delays in treatment that allow the symptoms to become more established as habits or preexisting mental conditions. In some cases, where a person already has a mental health disorder, converted symptoms will come on more slowly over time. These are generally harder to resolve.

Bibliography

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