The assessment, treatment, and understanding of patients with neurologic symptoms that remain unexplained after appropriate medical investigation continue to be a source of controversy and confusion. This is so despite the general consensus that they have a high prevalence in neurologic practice and often involve disproportionate usage of medical resources, with possible attendant iatrogenic complications. As many as 30 percent of patients seen in an outpatient neurologic practice are found to have unexplained medical illness, 10 percent of whom present with functional neurologic symptomatology. Although epidemiologic estimates are somewhat inconsistent because of variations in case definition and differences in ascertainment, the incidence of “conversion disorder” is generally agreed to be on the order of 4 to 12 cases per 100,000 population in a given year, with a prevalence derived from case registries of 50 per 100,000 population.

A variety of diagnostic terms have been applied to such individuals historically, with distinctions made on the number, type, and breadth of somatic symptoms claimed, the degree of associated distress, and the extent to which antecedent psychopathologic mechanisms are present. In the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), patients presenting with predominant neurologic symptoms of unexplained origin were assessed most commonly as having a conversion disorder, one of a family of somatoform disorders that also included somatization disorder, which required sexual and gastrointestinal symptoms in addition to neurologic and pain complaints, pain disorder, and hypochondriasis. Continuing research on these diagnostic categories, however, failed to support their predictive validity and reliability and has identified extensive comorbidities that resulted in distinctions between disorders that were more theoretical than real. In the recently released, revised edition, DSM-5, these specific diagnoses have been replaced by a simplified category entitled “Somatic Symptom Disorder.” Most saliently, the requirement for the existence of “medically unexplained symptoms” has been removed, with additional emphasis placed on the disproportionate thoughts, feelings, and behaviors associated with the somatic symptoms.

Most neurologic patients to be discussed in this chapter would likely qualify for the more specific term of “functional neurologic symptom disorder” if their symptoms did not conform with evidence for a recognized medical or neurologic condition and if significant distress or impairment in social, occupational or other important areas of functioning were present or medical evaluation was required ( Table 52-1 ). Although the classic presentation of the patient with conversion disorder has long been associated with an affect that seems disconnected with the degree of symptomatology and physical signs observed (“la belle indifference”), such emotional presentations are relatively rare and nonspecific; many patients with conversion disorder will, in fact, be quite concerned about their symptoms and associated functional deficits. The diagnosis continues to require the elimination of alternative explanations for illness behavior, such as malingering, in which symptoms are fabricated for material gain, and factitious disorder, in which symptoms are feigned in order to assume the sick role in the absence of other external incentives. Associated features include onset after stress or trauma, although this is not always present, and dissociative symptoms, such as depersonalization, derealization, and dissociative amnesia. A history of childhood abuse or neglect is sometimes obtained, but no specific genetic risk factors have as yet been identified. Shorter duration of symptoms and acceptance of possible psychological causation are indicators of a positive prognosis, whereas the presence of a comorbid personality disorder or documented physical illness or secondary financial gain are indicative of a worse course.

A persistent concern of clinicians is the possibility of misdiagnosis and the consequence of litigation or sanction if an organic etiology is excluded by definition through usage of a diagnosis of conversion disorder. This concern, however, appears to be misplaced, in that numerous studies have found that the misdiagnosis rate is quite low, remaining at approximately 4 percent over many decades and seemingly unaffected by the introduction of newer and more sensitive diagnostic technologies, such as neuroimaging.

The term “functional neurologic symptom disorder” offers no new insight into etiology or treatment selection, but benefits from being less pejorative and stigmatizing than the terms “hysteria”or “hypochondriasis” and is more mechanistically agnostic than diagnoses employing the terms “psychogenic” or “psychosomatic.” Because much of the research done to date utilizes varying terminology, many of these terms are used interchangeably in this review.

Although conversion disorder or functional neurologic symptom disorder was originally conceptualized as involving neurologic mechanisms by Charcot, subsequent formulations by Janet and Freud chose to emphasize psychologic processes of dissociation and conversion following a traumatic experience in the production of somatic symptoms. Hysteria, or more specifically “neurosis,” the term preferred by Charcot, was a heterogeneous entity encompassing a variety of symptomatic presentations, ranging from convulsions to paralyses and dystonias to hallucinations and dissociative reactions. The essential element of the disorder, in addition to its protean nature, was that no organic lesion could be recognized. This, however, did not mean that rules and laws regarding its symptomatic presentation could not be elicited through careful observation, and one-third of the lectures that Charcot delivered upon assuming his position as Chair of Nervous Diseases in the Faculty of Medicine in Paris were devoted to the subject. Although Charcot’s focus in his lectures on diagnosis and potential mechanisms was predominantly on central nervous system pathology, he came to accept the possibility of unconscious psychologic causation. Regardless of etiology, and in contrast to the views of other prominent neurologists such as S. Weir Mitchell, who thought conscious deception was involved, patients were to be viewed as having a true medical illness and fully deserving of therapeutic support and societal acceptance.

The classic hysterical attack took the form of psychogenic seizures, perhaps because of the role of suggestion and the housing at the Salpêtrière hospital of psychologically vulnerable and impressionable neurotic patients with those subject to true grand mal seizures. According to Charcot, three distinct stages could be observed. The first, the epileptoid, would last a few minutes and was associated with a variety of prodromes: a tightness in the head or the feeling of an obstruction in the throat, a cough or yawn, and pain in the abdomen, particularly over the ovaries in a woman. The patient would then fall, with apparent loss of consciousness and diminished breathing. In the second stage, the tonic phase, the patient would extend the arms and legs and go through a series of short and violent jerking movements alternating with periods of muscle relaxation. This would be followed by disordered random movements (“clownism”; Fig. 52-1 ) and the classic l’arc de cercle (“the hysterical arch”), with the patient arching their body backwards, resting only on their head and heels. Variations in contorted movements might also follow. In the third stage, the “attitudes passionelles,” more dramatic and profound emotional evocation was manifest, with the patients engaging in expressive mimicry of strongly felt past experiences, often yelling, crying, or engaging in complex reenactments of traumatic events. The episode at this point would end or repeat itself in a similar fashion. In some cases an extended post-episode confusional state might exist for several hours or, in some cases, days.

A case of psychogenic nonepileptic seizure at the Salpêtrière. The patient is exhibiting what Charcot termed the stage of “clownism.”

(From Desire-Magloire Bourneville D-M, Regnard P: Icononographie Photographique de la Salpêtrière, Paris, 1877-80.)

Complete presentations in the manner described were not common in Charcot’s day and quickly became even rarer, to the point of being primarily of historical interest today. What is important, however, is that many of the individual component parts persist as core elements of the varying functional nervous system disorders discussed in this chapter. Charcot’s contributions to treatment likewise provide the basis for the standard elements of psychotherapeutic intervention today. In essence, physicians should try to act psychologically, through exerting their powers of persuasion in as positive a manner as possible. The condition should be accepted by the physician, but only with the patient agreeing that the condition can be cured and only if the patient will join in the therapeutic work to be done. Reeducation, various forms of gradual increases in physical activity, and rudimentary techniques of muscle relaxation were tried and found to be helpful. Isolation of the patient to prevent social reinforcement of pathologic symptomatology was also recognized as important.

Evidence exists that many neurologists, although adept in differential diagnosis, remain uncomfortable in their management of such individuals and often erroneously believe them to be feigning or somehow deceptive in their presentation, even though Charcot himself stressed that this was not the case and that true hysteria could be distinguished from simulation and malingering. An in-depth interview of a representative sample of neurologists has found that the concept of conversion disorder is recognized and seen frequently in a normal clinician’s workload. The possibility of a functional condition was often recognized early in the clinical encounter but was not reported to limit the scope of the examination or subsequent laboratory evaluation. Patients themselves were viewed as difficult to deal with, and as more disabled and requiring more effort on the part of the clinician. Most neurologists thought a psychologic formulation of the condition was relevant to understanding the patient and treatment, but they themselves did not feel competent to construct one. Most felt that feigning and conversion disorders existed on a continuum and that deception could not be excluded. Given the prevalence of functional nervous system disorders and the degree to which clinicians remain discomforted by their presentation, an expanded research effort directed towards better characterization of patients, the development of more effective treatment options, and a more extensive educational outreach to treating physicians would seem warranted. This chapter reviews the most common types of functional neurologic symptom disorders and current approaches to their differential diagnoses, as well as possible treatment approaches.