Conversion Disorder (Functional Neurologic Symptom Disorder)

Christina Scully, M.D.

Basic Information

Definition

Conversion disorder (functional neurologic symptom disorder) presents with symptoms that affect voluntary motor or sensory function or that cause a transient loss of consciousness. Symptoms might include paralysis, blindness, numbness, or the inability to speak. Symptoms can be sporadic, sustained, acute, or chronic. The symptoms, following medical assessment, cannot be explained by a medical condition, direct effects of a substance, or a culturally sanctioned behavior or experience.

Diagnostic features provide evidence of internal inconsistency or incongruity with recognized features of neurological or medical disorders. The symptoms cause clinically significant distress and/or impairment in social, occupational, and other important areas of functioning and warrant medical evaluation. Oftentimes, there is a relevant psychological stressor present, although this is not required to establish the diagnosis. Functional symptoms are not voluntarily produced and are presumed to be unconsciously elaborated.

There is no well-validated physiologic model for conversion disorder, but advances in neuroscience and neuroimaging may reveal new etiologies. A patient diagnosed with conversion disorder should be periodically reevaluated for any medical etiology that has been slow to present or that may be newly diagnosable with advances in medical knowledge and technology.

Synonyms

Psychogenic nonepileptic seizure
Psychogenic movement disorder
Hysterical neurosis (historical)
Functional neurologic symptom disorder

ICD-10CM CODES
F44.4	Conversion disorder with motor symptom or deficit
F44.5	Conversion disorder with seizures or convulsions
F44.6	Conversion disorder with sensory symptom or deficit
F44.7	Conversion disorder with mixed symptom presentation
F44.89	Other dissociative and conversion disorders
F44.9	Dissociative and conversion disorder, unspecified
DSM-5: 300.11

Epidemiology & Demographics

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Incidence ∼5 to 10/100,000 in general population, 20 to 100/100,000 in hospital inpatients
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All ages, including early childhood, but rare in children younger than 10 years old

Physical Findings & Clinical Presentation

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Presents with one or more motor symptoms (e.g., paralysis, aphonia, difficulty swallowing), sensory symptoms (loss of sensation, double vision, blindness, deafness), or a nonepileptic seizure, or a combination of these symptoms.
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Physical exam findings that are not consistent with anatomical pathways or physiologic mechanisms, such as Hoover sign (weakness of hip extension returns to normal strength with contralateral hip flexion against resistance), weakness of plantar flexion on the exam table in an individual able to walk on tiptoes, positive tremor entrainment test, normal EEG or closed eyes with resistance to opening during nonepileptic seizure, or tubular vision.
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The symptoms or signs persist whether the patient is observed or unobserved, though are typically worse when the patient is attentive to them.
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May occur in the context of documented medical illness (e.g., a patient with epileptic seizure may also have psychogenic seizure).
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May have comorbid axis I or axis II disorders, commonly depression; generalized anxiety; PTSD; or borderline, histrionic, or narcissistic personality disorder.

Etiology

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Complex interplay of neurologic and psychological factors is not well understood.
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The classic psychodynamic hypothesis is that the conversion symptom is preceded by psychological conflict or stressor and functions to express and manage the psychological distress—that is, “convert” the distress into a neurologic symptom.
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A neurobiologic hypothesis suggests an abnormality in neural networks, possibly triggered by emotional stress. Brain imaging studies suggest alterations in processing of sensory and motor signals.
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Associated with psychiatric comorbidities, most commonly depression, anxiety, PTSD, and personality disorders (most commonly histrionic, borderline, or narcissistic).
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Associated with trauma, interpersonal conflicts, and other life stressors.
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Associated with childhood sexual abuse in many, but not all, studies.
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Associated with preexisting neurologic illness.
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Associated with physical injury that may occur immediately prior to onset.
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May occur after general anesthesia.
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Family history of medical or psychiatric illness is common.

Diagnosis

Diagnosis is specific to symptom type:

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Psychogenic nonepileptic seizure
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Weakness or paralysis
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Abnormal movement (tremor, dystonic movement, myoclonus, gait disorder)
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Swallowing symptom
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Speech symptom (e.g., dysphonia, slurred speech)
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Anesthesia or sensory loss
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Special sensory symptom (e.g., visual, olfactory, auditory)
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Mixed symptoms

Differential Diagnosis

Broad differential diagnosis depending on presenting signs and symptoms, including movement disorders, seizure, stroke, spinal disorders, malignancy, vasculitis, infectious disease, autoimmune disorders, vitamin B₁₂ deficiency, migraine, dystonia, limbic encephalopathy, stiff person syndrome, somatic symptom disorder, factitious disorder, and malingering.

Laboratory Tests

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Laboratory tests or procedures needed to rule out other medical conditions (e.g., EEG for seizures, EMG for lower motor neuron paralysis, optokinetic drum test in blindness).

Treatment

Nonpharmacologic Therapy

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Education about illness including explanation and diagnosis. A multidisciplinary treatment team including a neurologist and psychiatrist can be helpful for some patients.
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Medical providers who fail to explain the diagnosis, misattribute the symptoms, and/or continue to pursue medical investigations and procedures can contribute to the patient’s belief that there is an irreversible medical cause and thereby risk perpetuating the symptoms.
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Cognitive behavioral therapy is often the treatment of choice, although evidence is mixed.
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A long tradition of psychodynamic therapy exists but has not been validated by controlled trials.
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Treatment success has been associated with a caring, long-term relationship between patient and physician.
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Physical and occupational therapy can help reestablish normal function and is important for maintaining strength and function in extended cases of paralysis.
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Studies have shown no additional benefit to hypnosis, although case records describe successful treatment with hypnosis.
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Family therapy and group therapy.

General Rx

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Antidepressants may be helpful for underlying mood or anxiety disorders.
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Sedation and abreaction: One study showed sedation with propofol improved symptoms. Abreaction functions as a pharmacologically induced hypnosis in which a lightly sedated patient is interviewed. Abreaction is rarely used.
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Inpatient psychiatric treatment or physical rehabilitation may be required depending on acuity, comorbidities, and functional impairment.

Disposition

Long-term follow-up essential for recurrent conversion symptoms and underlying mood disorders.

Pearls & Considerations

Comments

Good prognostic factors: sudden onset, presence of psychological stressors at onset, short duration between diagnosis and treatment, high level of intelligence, absence of other psychiatric or medical disorders. Poor prognostic factors: severe disability, long duration of symptoms, age >40 yr at onset, and convulsions or paralysis as presenting symptoms.

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Studies show an association between sexual trauma and conversion symptoms, although evidence does not support causality due to confounding and methodologic factors.
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Although not well demonstrated, some argue that conversion and somatic symptoms are more prevalent in cultures without an articulated concept of affective disorder or in which mental illness is highly stigmatized.
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A strong therapeutic alliance and education about illness are essential treatment components.

Ferri – Conversion Disorder (Functional Neurologic Symptom Disorder)