Functional Neurological Symptom Disorder (Conversion Disorder)

In this series, I dig a little deeper into the meaning of psychological terms. This week’s term is functional neurological symptom disorder, formerly known as conversion disorder.

Conversion disorder is a type of somatic disorder that involves the conversion of mental illness into neurological-type symptoms, involving sensory and/or motor impairments. In the DSM-5, the name changed to functional neurological symptom disorder, but I’ll refer to it here as conversion disorder, as it’s less of a mouthful.

Assessment

Before making a diagnosis, it’s important to rule out physical, and particularly neurological, causes for the symptoms. The physical workup would typically include electroencephalogram (EEG) and MRI testing. Ideally, a neuropsychiatry specialist, who has dual specialties in neurology and psychiatry, would evaluate the patient. Otherwise, both a neurologist and psychiatrist would assess the patient.

Conversion disorder symptoms tend to present in unusual patterns or fluctuate over time in ways that wouldn’t be expected if the source of the problem was neurological. For example, people who have deficits in one leg may have a positive Hoover sign. When sitting/lying, if we raise one leg, we reflexively put downward pressure on the other leg. Someone with conversion disorder may be unable to press down with their weak leg on command, but if they raise their other leg, the other leg presses down reflexively as a positive Hoover sign, suggesting the problem is not neurological.

Some signs may disappear when the patient is focusing their attention on something else; for example, a left-hand tremor might temporarily disappear while a patient focuses on doing a task with their right hand. That doesn’t mean that the patient is faking it, though; conversion disorder is involuntary.

Symptoms

Conversion disorder involves one or more symptoms that affect either movement or sensation that can’t be explained by a neurological disorder or other medical condition. The symptoms significant distress or impairment in multiple areas of functioning.

Symptoms can include:

• tremor
• non-epileptic seizures
• abnormal limb posturing
• impaired coordination or balance
• weakness
• limb paralysis
• loss of sensation
• loss of senses (e.g. hearing, vision)
• tunnel vision or double vision
• difficulty swallowing
• urinary retention
• episodes of unresponsiveness

Symptoms are not under conscious control, and conversion disorder is not a form of factitious disorder or malingering.

In the past, doctors commonly conducted “Amytal interviews,” which involved assessing the patient while they were medicated with a barbiturate to disinhibit them. However, the risk of side effects is considerable, and this is no longer routinely used.

Pathophysiology

The term conversion disorder comes from the psychoanalytical perspective that repressing emotional conflict into the unconscious causes that conflict to be converted into physical symptoms.

From a sociocultural perspective, conversion disorder may allow for the expression of distress in a way that’s more culturally acceptable (i.e. physically rather than psychologically) and thus more likely to garner social support.

Other explanations for conversion disorder include that it’s a form of freeze response related to attachment issues, or that it’s a form of conditioned response.

Some studies have shown a number of changes in the brains of people with conversion disorders. These include changes in regional cerebral blood flow and hypoactivity of the dominant hemisphere of the brain, along with overactivity of the nondominant hemisphere.

While I’m sure in the past plenty of neurological conditions were written off as hysteria, in the present day, the rates of missed diagnosis of underlying organic disorders are less than 5%. However, by 10-year follow-up, about 25% of people have gone on to develop a neurological disorder like multiple sclerosis, neurodegenerative diseases, or peripheral neuropathy.

Risk factors

Conversion disorder is rare, occurring in about 4-12 per 100,000 people per year.

It can happen at any age, but it’s most common in the teens through the thirties. It’s more common in females than males, with females making up 60-75% of cases. Symptom onset and flareups tend to occur abruptly and are often triggered by stress or trauma.

A family history of conversion disorder increases the risk. Having another mental disorder (e.g. a mood disorder, dissociative disorder, or personality disorder) or a neurological disorder can also increase the risk of developing conversion disorder. Past physical or sexual abuse or childhood neglect are also risk factors.

Conversion disorder is more common in people who live in rural areas, have limited education and health literacy, and are of low socioeconomic status. That’s an interesting finding, and I didn’t come across any explanation as to why that might be.

The prognosis is better in people who don’t have a co-occurring mental disorder. Other factors associated with a better prognosis include initial presentation of symptoms at a younger age, early diagnosis, acute onset of symptoms, short duration of symptoms, presence of an identifiable stressor, male gender, and higher intelligence. I find the intelligence association to be quite fascinating.

Treatment

Cognitive behavioural therapy is the primary form of treatment. Hypnosis may also be helpful. Physical therapy may help people to gain a greater sense of control over the body and re-train the nervous system. Attention-shifting away from the problem area can help to improve functioning.

One study found that people with conversion disorder tend to have less sensitivity to physiological signals linked to emotions, as well as a lack of awareness of their emotions. This may be a useful target for therapy for people with this disorder.

Medication isn’t indicated for the treatment of conversion disorder. However, people with the disorder often have co-occurring mental disorders like depression that may warrant medication.

It’s crucial for patients to have supportive treatment providers who are validating and don’t write their problems off as being all in their heads. Ideally, there would be long-term consistency with providers and work on distress tolerance and coping skills to reduce relapses.

I came across this condition a few times over the course of my nursing career, including one patient who would typically need to use a wheelchair during relapses. It’s truly fascinating what the brain can do. Have you ever come across conversion disorder/functional neurological symptom disorder?

References

• Brigham and Women’s Hospital: Standard of Care: Functional Neurologic Disorder
• Mayo Clinic: Functional Neurologic Disorder/Conversion Disorder
• Medscape: Conversion Disorders
• Merck Manual Professional Version: Conversion Disorder
• Williams, I. A., Reuber, M., & Levita, L. (2021). Interoception and stress in patients with functional neurological symptom disorder. Cognitive Neuropsychiatry, 26(2), 75-94.