INTRODUCTION — Conversion disorder (functional neurologic symptom disorder) is characterized by neurologic symptoms (eg, weakness, abnormal movements, or nonepileptic seizures) that are inconsistent with a neurologic disease, but nevertheless are genuine, cause distress and/or psychosocial impairment [1]. The disorder is common in clinical settings and often has a poor prognosis [2-5].
This topic reviews the terminology, diagnosis, and differential diagnosis of conversion disorder. The epidemiology, pathogenesis, prognosis, clinical features, assessment, and treatment are discussed separately, as are specific subtypes of conversion disorder (psychogenic nonepileptic seizures and psychogenic movement disorders):
●(See "Conversion disorder in adults: Epidemiology, pathogenesis, and prognosis".)
●(See "Conversion disorder in adults: Clinical features, assessment, and comorbidity".)
●(See "Conversion disorder in adults: Treatment".)
●(See "Psychogenic nonepileptic seizures: Etiology, clinical features, and diagnosis".)
●(See "Functional movement disorders".)
TERMINOLOGY — Many terms are used to describe neurologic symptoms or syndromes in the absence of disease pathology, including [6,7]:
●“Conversion disorder” (consistent with DSM-5 [1]), “somatization,” “somatoform,” or “psychogenic,” meaning that the symptoms are psychological and possibly caused by a remote or recent stressor. These terms are consistent with referral to psychiatric services, but they introduce etiologic assumptions that often cannot often be proven; as an example, the term conversion disorder is based upon the unproven psychoanalytic hypothesis that overwhelming affect, psychological conflict, or stress are unconsciously converted into symptoms that suggest a neurologic disorder [8]. In addition, terms such as psychogenic may also connote “faking” or “crazy” behavior and thus alienate patients [9].
●“Functional” (also consistent with DSM-5 [1]), meaning that the symptoms arise from abnormal nervous system functioning in the absence of structural pathology (eg, functional weakness). This term is etiologically neutral and usually acceptable to patients [10,11]. However, it may seem vague and does not indicate that psychosocial factors may be important.
●“Dissociative (motor, sensory, or seizure) disorder” (consistent with ICD-10 [12]), meaning sensation or control of movement is separated from awareness. The term is particularly useful to describe the trance-like state seen in nonepileptic seizures, but also implies that patients are suffering depersonalization or derealization (which is frequently not true).
●“Medically unexplained,” meaning that the etiology is unknown. The term is neutral, but may imply that the clinician does not know what is wrong and is incapable of rendering a diagnosis and treatment [11]. In addition, it is difficult to prove that a symptom cannot be medically unexplained [1].
●“Psychosomatic,” meaning that the symptom is due to the interaction between the mind and body. However, this term is often interpreted to mean the same thing as somatization or psychogenic.
●“Nonorganic” or “pseudoneurologic,” meaning that the patient does not have a disease with a known pathologic basis. The terms emphasize what patients do not have rather than what is present, and ignore the central nervous system underpinning of psychological phenomena.
●“Hysteria,” which originally meant that symptoms were due to uterine pathology and implied that the disorder was exclusive to females. More recent definitions include emotional excess, overwhelming fear, and psychiatric symptoms involving disturbances of mental, sensory, vasomotor, and visceral functions. This term is generally considered a historic artifact.
DIAGNOSIS — In patients with neurologic symptoms (eg, abnormal movements or seizures) that are not caused by neurologic disease, the diagnosis of conversion disorder (functional neurologic symptom disorder) should be made after the neurologist has established positive clinical findings that are incompatible with disease or are inconsistent across different parts of the examination [7,10,13,14]. In addition, clinicians and researchers frequently diagnose conversion disorder subtypes such as psychogenic/functional movement disorders or psychogenic nonepileptic seizures.
Prior to 2013, conversion disorder could be diagnosed according to the criteria in either the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) [15], or the World Health Organization's International Classification of Diseases-10th Revision (ICD-10) [12]. However, neither nosologic system was widely used in its entirety because many patients did not fulfill all of the criteria [10]. In particular, both nosologies stipulated that conversion symptoms were associated with or caused by psychologic factors. For many patients, psychologic factors are not identifiable, and even when they are identified, it’s not always clear that they are etiologically relevant [10].
In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), the diagnosis of conversion disorder does not require that clinicians identify psychological factors associated with the conversion symptoms [1]. (Nevertheless, clinicians should continue to look for psychological factors where relevant.) In addition, clinicians no longer need to establish that the symptom is not feigned; by contrast, DSM-IV-TR required that the symptom was not intentionally produced [15]. DSM-5 classifies conversion disorder among the somatic symptom and related disorders, which are marked by somatic symptoms that are associated with distress and psychosocial impairment.
Diagnostic and Statistical Manual, Fifth Edition (DSM-5) — A DSM-5 diagnosis of conversion disorder requires each of the following criteria (table 1) [1]:
●One or more symptoms of altered voluntary motor or sensory function
●Clinical findings that demonstrate incompatibility between the symptom and recognized neurologic or general medical conditions (eg, Hoover's sign of functional limb weakness or a positive entrainment test for functional tremor)
●The symptom or deficit is not better explained by another medical or mental disorder
●The symptom or deficit causes significant distress, psychosocial impairment, or warrants medical evaluation
The diagnosis rests upon positive clinical findings that indicate the symptom is incongruent with anatomy, physiology, or known diseases, or is inconsistent at different times (eg, a “paralyzed” limb will move inadvertently when the patient is distracted by performing movements in their unaffected limb) [1]. However, normal findings on physical examination (eg, reflexes) or normal laboratory tests do not constitute “positive clinical findings.”
DSM-5 describes several subtypes of conversion disorder that are based upon the presenting symptom or deficit [1]:
●Seizures or attacks – These events are also called psychogenic nonepileptic seizures, and are marked by abnormal generalized limb shaking and apparent impaired or loss of consciousness resembling epileptic attacks or fainting (syncope) (see "Psychogenic nonepileptic seizures: Etiology, clinical features, and diagnosis")
●Weakness or paralysis
●Abnormal movement – Includes dystonic movement, gait disorder, myoclonus, and tremor (see "Functional movement disorders")
●Anesthesia or sensory loss – Includes symptoms such as loss of touch or pain sensation
●Special sensory symptom – Includes visual (eg, double vision, blindness, or tubular visual field [tunnel vision]), hearing (eg, deafness), or olfactory disturbance
●Swallowing symptom – This symptom is also called globus sensation or globus pharyngeus and is characterized by the sensation of a lump in the throat (see "Globus sensation")
●Speech symptom – Includes dysphonia and slurred speech
●Mixed symptoms – Two or three different subtypes of symptoms are present (eg, paralysis plus blindness)
More common conversion disorder subtypes include nonepileptic attacks, sensory loss, weakness and paralysis, and abnormal movement [16].
Conversion disorder should not be diagnosed primarily because the patient has a history of other psychiatric disorders (eg, major depression or a personality disorder) or because neurologic examination and laboratory tests are normal [1,7]. Clinicians must ensure that the symptoms are not better explained by a neurologic or other general medical disease, and should bear in mind that our knowledge of neurologic disease, anatomy, and physiology is incomplete. Neurologic and general medical disorders that are included in the differential diagnosis are discussed separately. (See 'Neurologic and general medical disorders' below.)
However, conversion disorder can be diagnosed in patients who have comorbid neurologic diseases, provided there is evidence that the diseases do not better explain the conversion symptoms. (See "Conversion disorder in adults: Clinical features, assessment, and comorbidity", section on 'Neurologic and general medical disorders'.)
In diagnosing conversion disorder, it is not necessary to identify conflicts or other stressors associated with conversion symptoms (although doing so may help patient management) [1,10,17,18]. Psychological factors are frequently observed in patients with conversion symptoms, but this is not always the case. In addition, when psychological factors are present, it is difficult to establish the etiologic relationship between these factors and conversion disorder because psychological factors are ubiquitous [1,10]. Trauma, conflicts, and stressors may have a specific etiologic relationship with conversion disorder, a nonspecific relationship (ie, psychologic factors may contribute to onset of psychiatric disorders in general), or the presence of psychological factors may be coincidental. However, a close temporal relationship between a stressor and onset or worsening of conversion symptoms may aid diagnosis (eg, “hand dystonia after signing an unwelcome document” [17]), especially if there is a prior history of conversion symptoms under similar circumstances [1]. Additional information about premorbid clinical factors and the etiology of conversion disorder is discussed separately. (See "Conversion disorder in adults: Epidemiology, pathogenesis, and prognosis", section on 'Premorbid clinical factors'.)
The diagnosis of conversion disorder does not require clinicians to establish that the symptom is not intentionally produced [1,10,17-19]. However, if there is evidence that the symptoms are feigned, then the diagnosis of conversion disorder should not be made. Evidence that suggests patients with conversion disorder are not feigning includes the consistency among different patients in how they report their symptoms, the common pattern of comorbidity and physical evidence (eg, abnormal shoe wear, disuse atrophy, and contractures) across patients, and the distress and disability that is observed in follow up studies [7]. It is also worth noting that awareness of what is happening may not be “all or nothing;” rather, there may be gradations of awareness along a continuum, and the patient’s level of awareness may change over time [6,7].
Exposure to a common precipitant may lead to shared conversion symptoms in a group of people (“mass hysteria”) [20-22]. Conversion disorder is diagnosed only in those individuals manifesting significant distress or impairment.
International Classification of Diseases - 10th Revision (ICD-10) — As stated above (see 'Diagnosis' above), the ICD-10 criteria are often not used in their entirety because many patients with the disorder do not fulfill all of the criteria [10], particularly the criterion that stipulates conversion symptoms are caused by psychological factors.
The ICD-10 classifies conversion disorder among the dissociative disorders, which are characterized by disruption of awareness, memory, identity, sensations, and control of body movements [12]. Diagnostic equivalents to conversion disorder within ICD–10 include:
●Dissociative motor disorders
●Dissociative anaesthesia and sensory loss
●Dissociative convulsions
●Mixed dissociative disorders
Dissociation in this context often includes a feeling of disconnection from one’s own body (depersonalization) or from one’s environment (derealization) [7].
Diagnosis of ICD–10 conversion disorder equivalents requires each of the following criteria [12]:
●Symptoms suggesting the specific dissociative disorder (motor, sensory, convulsions, or mixed)
●No evidence of neurologic or general medical disorders that explain the symptoms
●Evidence that the specific dissociative disorder is caused by psychological factors such as stressful events, intractable problems, or interpersonal difficulties
Although ICD-10 does not explicitly require clinicians to exclude feigning of symptoms to diagnose dissociative movement or sensation disorders or dissociative seizures, the need to do so is implied in the supporting text that discusses the differential diagnosis and the difficulty in distinguishing dissociation from conscious simulation of loss of movement and sensation [12].
DIFFERENTIAL DIAGNOSIS — The differential diagnosis for conversion disorder (functional neurologic symptom disorder) includes neurologic and general medical disorders, psychiatric disorders, and malingering [1].
Neurologic and general medical disorders — The differential diagnosis for conversion disorder includes many general medical disorders and all neurologic diseases, including multiple sclerosis, myasthenia gravis, movement disorders, stroke, epilepsy, and spinal disorders [1,12]. Clinicians faced with symptoms that are difficult to interpret should exercise caution in diagnosing conversion disorder, no matter how much the psychiatric history suggests it. Patients may notice symptoms of an occult disease during its early stage when signs on physical examination or laboratory test abnormalities are not readily apparent [23]. In addition, more unusual neurologic diseases such as stiff person syndrome, autoimmune limbic encephalitis, and frontal lobe epilepsy may present with unusual features such as symptom variability, bizarre behavior (eg, cycling leg movements or pelvic thrusting), or other symptoms (eg, emotional lability) that might lead the unwary to consider a “psychogenic” disorder. The effects of a neurologic disease can be frightening, which may lead patients to exaggerate their symptoms to convince a doctor about their problem [24]. The probability that apparent conversion symptoms are actually the harbinger of neurologic/general medical disease may be greater in patients with gait disorders or comorbid psychiatric disorders [25].
However, a balance must be struck between not missing neurologic/general medical disorders and failing to positively diagnose conversion disorder. The frequency of erroneously diagnosing conversion disorder in patients who are subsequently found to have a neurologic illness (that with hindsight explained the initial symptoms) is generally regarded as low [17]:
●A systematic review of 27 studies (mostly retrospective; median duration of follow-up was five years) found that among 1466 patients initially diagnosed with conversion symptoms, the frequency of misdiagnosis was approximately 4 percent [25].
●A subsequent study prospectively followed a group of 209 patients initially diagnosed with conversion disorder, who were part of 1030 neurology outpatients with symptoms that were considered somewhat or not at all explained by a recognizable neurologic disease [16]. After a median follow-up of 19 months, the investigators determined that the initial diagnosis was wrong in none of the conversion disorder patients and in 0.4 percent of the entire group.
By contrast, misdiagnosis of other psychiatric and neurologic disorders occurs in 6 to 23 percent of patients [26-28].
In addition, many patients have both conversion disorder and a neurologic condition [29]. As an example, approximately 10 percent of patients with psychogenic nonepileptic seizures also have epilepsy. (See "Psychogenic nonepileptic seizures: Etiology, clinical features, and diagnosis".)
The differential diagnosis of conversion disorder includes all neurologic diseases [23], including:
Multiple sclerosis — Multiple sclerosis and conversion disorder both can involve motor and sensory symptoms, but patients with conversion disorder will have inconsistent limb movements, whereas, patients with multiple sclerosis alone will not. Multiple sclerosis is also distinguished by characteristic lesions on magnetic resonance imaging (MRI). (See "Evaluation and diagnosis of multiple sclerosis in adults", section on 'Diagnosis'.)
Myasthenia gravis — Myasthenia gravis and conversion disorder can both present with weakness that changes over time, but patients with conversion disorder will have positive evidence of inconsistency without fatigue. Myasthenia gravis is often associated with bulbar symptoms, diplopia, and ptosis, which are rare in conversion disorder; myasthenia gravis is also differentiated by findings on serologic tests for autoantibodies and on electrophysiologic studies (repetitive nerve stimulation studies and single-fiber electromyography) that are not present in conversion disorder. (See "Diagnosis of myasthenia gravis".)
Movement disorders — Psychogenic movement disorders and movement disorders due to defined neurologic disease both present with abnormal movements; however, psychogenic movement disorders are characterized by several clinical features, especially signs and symptoms that are inconsistent over time and incongruent with recognizable neurologic disease. (See "Functional movement disorders".)
Stroke — Stroke and conversion disorder can both manifest with weakness, but patients with conversion disorder have inconsistent limb movements, whereas patients with stroke alone do not. (See "Overview of the evaluation of stroke".)
Spinal disorders — Spinal disorders (eg, cervical myelopathy or lumbar nerve root entrapment) and conversion disorder may each cause weakness or sensory disturbance. However, patients with conversion disorder have inconsistent limb weakness whereas patients with spinal disorders should not.
Epilepsy — Epilepsy and psychogenic nonepileptic seizures both manifest with unresponsive behavior and motor movements that suggest a generalized convulsion, complex partial seizure or syncope. However, psychogenic nonepileptic seizures and epileptic seizures are distinguished by recording an event on video electroencephalography and analyzing the clinical and electrographic features. (See "Psychogenic nonepileptic seizures: Etiology, clinical features, and diagnosis".)
In addition, some examples of more unusual neurologic diseases to consider in the differential diagnosis of conversion disorder include:
Autoimmune limbic encephalitis — Limbic encephalitis and conversion disorder may present with seizures, cognitive problems, and mood changes. Positive findings on neuroimaging, electroencephalography (EEG), lumbar puncture, or serologic testing for antibodies are generally found in limbic encephalitis but not conversion disorder. (See "Paraneoplastic and autoimmune encephalitis".)
Stiff person syndrome — Impaired ambulation, variable limb stiffness, and spasms can occur in both stiff person syndrome and conversion disorder. However, stiff person syndrome is usually denoted by the presence of anti-glutamic acid decarboxylase antibodies in association with this clinical picture. (See "Stiff-person syndrome".)
Laryngeal dystonia — Dysphonia (manifesting with whispering or hoarseness) can occur in both laryngeal dystonia (spasmodic dysphonia) and conversion disorder (functional dysphonia). Laryngeal dystonia may be either a primary pathologic phenomenon or secondary to illnesses such as Parkinson disease or multiple systems atrophy. Clues that the speech impairment may be due to conversion disorder include the presence of a normal cough or singing voice. The diagnosis of conversion disorder is confirmed by normal vocal cord movement on laryngoscopy. (See "Etiology, clinical features, and diagnostic evaluation of dystonia", section on 'Laryngeal dystonia' and "Hoarseness in adults", section on 'Spasmodic dysphonia'.)
Psychiatric disorders — The differential diagnosis for conversion disorder includes somatic symptom disorder, depersonalization/derealization disorder, and factitious disorder [1].
Somatic symptom disorder — Somatic symptom disorder subsumes the disorders previously identified as hypochondriasis and somatization disorder, but also includes patients with somatic symptoms that are explained by disease [1]. Somatic symptoms that cause distress and/or impairment can occur in both somatic symptom disorder and conversion disorder, and some patients may warrant both diagnoses. Patients with somatic symptom disorder suffer from an excessive response to somatic symptoms, but do not typically have loss of function that is clearly incompatible with anatomy, physiology, and recognized neurologic or general medical illnesses; the disorder can thus occur in patients whose symptoms are explained by recognized diseases. By contrast, conversion disorder is characterized by evidence of inconsistency between the clinical findings and recognized disease. Also, the excessive thoughts, feelings, and behaviors that occur in somatic symptom disorder may not be present in conversion disorder. (See "Somatic symptom disorder: Epidemiology and clinical presentation" and "Somatic symptom disorder: Assessment and diagnosis".)
Depersonalization/derealization disorder — Depersonalization (feeling disconnected from one’s own body) and/or derealization (feeling disconnected from one’s environment), which characterize depersonalization/derealization disorder, can also occur in conversion disorder, and some patients warrant both diagnoses [1]. However, conversion disorder presents with symptoms of altered voluntary motor or sensory function, and clinical findings that demonstrate incompatibility between the symptoms and recognized neurologic conditions, whereas depersonalization/derealization disorder does not. (See "Depersonalization/derealization disorder: Epidemiology, pathogenesis, clinical manifestations, course, and diagnosis".)
Factitious disorder — Neurologic symptoms that are not due to disease are present in conversion disorder, and can occur in factitious disorder as well. The primary distinction is that patients with factitious disorder deliberately feign symptoms and deceive clinicians to be a patient and obtain medical care. In conversion disorder, there is no clear evidence that symptoms have been simulated for the purpose of receiving medical care [1,10,17-19].
A clue that patients are feigning includes varying accounts of symptoms to different clinicians. However, it is possible to establish feigning only if the patient acknowledges deliberately producing symptoms, or if other evidence demonstrates a major inconsistency between reported and observed function (eg, a patient who reports an inability to walk is subsequently observed on a video recording playing tennis). Minor discrepancies are in keeping with the variable nature of conversion symptoms, which tend to worsen when attention is paid to them.
Additional information about factitious disorder is discussed separately. (See "Factitious disorder imposed on self (Munchausen syndrome)".)
Malingering — Malingering and conversion disorder are both characterized by symptoms that lack a pathologic basis [1]. The essential feature of malingering is intentionally faking or exaggerating symptoms for an obvious external benefit, such as money, housing, medications, or avoiding work or criminal prosecution. Malingering is a behavior and not a psychiatric disorder. In conversion disorder there is no evidence of intentionally producing symptoms [1,10,17-19].
Clinicians should consider the possibility of malingering if any of the following is present:
●Multiple inconsistencies in the patient’s history
●Nonadherence with diagnostic evaluation or treatment
●Antisocial personality disorder
●Medical-legal context (eg, patient is referred by an attorney for evaluation)
Other clues that patients are feigning symptoms are discussed above. (See 'Factitious disorder' above.)
SUMMARY
●Many terms are used to describe neurologic symptoms or syndromes in the absence of disease pathology, including: conversion disorder, functional, somatization, somatoform, psychogenic, dissociative disorder, medically unexplained, psychosomatic, nonorganic, pseudoneurologic, and hysteria. (See 'Terminology' above.)
●The diagnosis of conversion disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) is summarized in the table (table 1). (See 'Diagnosis' above.)
●The differential diagnosis for conversion disorder includes:
•Neurologic and general medical disorders (eg, multiple sclerosis, myasthenia gravis, movement disorders, stroke, spinal disorders, and epilepsy)
•Psychiatric disorders (eg, somatic symptom disorder, depersonalization/derealization disorder, and factitious disorder)
•Malingering
(See 'Differential diagnosis' above.)
