CHAPTER 20 CONVERSION AND DISSOCIATION SYNDROMES
Social historians have confidently asserted that conversion hysteria has disappeared from clinical practice, to be replaced by syndromes characterized by fatigue and other medically unexplained disorders.1,2 Although the florid manifestations of hysteria seen in the days of Pierre Janet are less common in the 21st century, the evidence from clinical practice is that patients with conversion disorders are not infrequently encountered by neurologists in both outpatient and inpatient settings.3 Indeed, it has been shown that symptoms considered “functional,” “psychogenic,” “medically unexplained,” or “hysterical” account for up to one third of new referrals to neurology outpatient departments.3,4 In a German survey, Rief and colleagues5 found a 2% base rate of unexplained paralysis or localized weakness in the population and a 5% base rate for “impaired coordination or balance” and “unpleasant numbness or tingling sensations.” In this chapter, the diverse manifestations of conversion and dissociation disorders are described, and the advances in approaches to treatment are outlined.
PROBLEMS WITH DEFINITION
There are a number of problems with the definition of the conversion disorder. First, physical disorder must be excluded, but the rate of neurological comorbidity is known to be high in patients with conversion disorder,6 and distinguishing which symptoms are accounted for by organic disease and which are not can be difficult. Second, it is stated that6a a temporal association between a psychological stressor and the onset on the disorder should be identified, but in practice, this is often impossible to establish, and doing so depends to a large extent on the skill of the interviewing physician. Finally, by definition, the process should be unconsciously mediated, but in practice it is difficult (some authorities would say impossible) to distinguish between symptoms that are not consciously produced and those that are intentionally manufactured. The Diagnostic and Statistical Manual of Mental Disorders, 4th edition,6a provides no criteria for distinguishing conscious from unconscious intent, and many authors have argued that the criteria of whether the patients are consciously aware of producing these symptoms should be excluded from the diagnosis of conversion disorder.7
A question often asked by neurologists, when confronted with a patient with unexplained loss of function of the limb, is “How do I distinguish between conversion disorder, factitious disorder, and malingering?” For the reasons just described, it is difficult to answer this question, because a patient’s “awareness” or “motivations” are not knowable. Various attempts have been made to provide adequate definitions, but all have their limitations (Table 20-1). Attempts to “demedicalize” this complex diagnostic field have introduced the concepts of “free will” and patient choice,8 and motor symptoms of hysteria have been discussed as “disorders of willed action.”9 Neurologists require considerable skills to diagnose and manage these conditions, which can be among the most taxing in the speciality.10
The term conversion is conventionally applied to somatic symptoms, whereas if the symptom is psychological (e.g., a loss of memory or an external hallucination) rather than physical (e.g., a loss of power), it is regarded as dissociative. Dissociation has attracted considerable interest, and in a major review of the topic, Holmes and colleagues (2005)11 drew a distinction between two qualitatively distinct, clinically relevant forms of dissociation, labeled compartmentalization (type 1) and detachment (type 2)12 (Table 20-2). Compartmentalization phenomena are characterized by impairment in the inability to control processes or actions that would usually be amenable to such control and that are otherwise functioning normally. This category encompasses unexplained neurological symptoms (including dissociative amnesia) and benign phenomena such as those produced by hypnotic suggestion. In contrast, detachment phenomena are characterized by an altered state of consciousness associated with a sense of separation from the self, the body, or the world. Depersonalization, derealization, and out-of-body experiences constitute archetypal examples of detachment in this account. Evidence suggests that these phenomena are generated by a common pathophysiological mechanism involving the top-down inhibition of limbic emotional processing by frontal brain systems. Although these two types of dissociation are typically conflated, evidence suggests that different pathological mechanisms may be operating in each case.
TABLE 20-2 Classification of Two Types of Pathological Dissociation
| Type 1 Dissociation (Compartmentalization) | Type 2 Dissociation (Detachment) |
|---|---|
| Conversion disorders | Depersonalization/derealization |
| Dissociative amnesia | Peritraumatic dissociation |
| Dissociative fugue | Out-of-body experiences |
| Dissociative identity disorder | Autoscopy (?) |
From Brown RJ: The cognitive psychology of dissociative states. Cogn Neuropsychiatry 2002; 7:221-235.
Support for the compartmentalization model comes from psychophysiological research, which suggests that psychogenic illness is associated with a deficit in attentional, conscious processing and the preservation of preattentive, preconscious processes. According to Brown,13 there is very little difference between “negative” symptoms, such as sensory loss and paralysis, and “positive” symptoms, such as tremor and dystonia, in terms of basic underlying mechanisms. According to this view, all symptoms result from a loss of normal high-level attentional control over low-level processing systems; in this sense, all symptoms can be viewed as involving a form of compartmentalization. In each case, the “dissociation” between high- and low-level control results from the repetitive reallocation of high-level attention onto “rogue representations” in memory, causing low-level attention to misinterpret this stored information as an account of current rather than past processing activity. The model is shown diagrammatically in Figure 20-1.
EPIDEMIOLOGY
In 1976, an editorial in the British Medical Journal suggested that hysteria was “virtually a historical curiosity in Britain.”14 Despite this assertion, the published evidence suggests that it is as common as other disabling conditions such as multiple sclerosis and schizophrenia.15 In a comprehensive review of the literature, Akagi and House15 concluded that the lowest prevalence data suggested a rate of about 50 per 100,000 for cases of conversion disorder known to health services at any one time, with perhaps twice that number affected over a 1-year period. These prevalence studies suggest that the burden of disability associated with chronic hysteria is far higher than a typical practicing psychiatrist might expect or than is reflected in standard textbooks of psychiatry or clinical neurology.
CLINICAL FEATURES
Conversion Disorder
Motor Symptoms
The Clinical Approach
The physician must not only rule out neurological disorder with the usual methods of history taking, examination, and investigation, but at the same time seek the “positive signs” of hysteria and establish that there is an appropriate psychosocial background for the emergence of medically unexplained symptoms. Since the mid-1990s, diagnostic procedures have improved, and the availability of noninvasive, accurate imaging has drastically reduced the rates of organic pathology that remains undetected in patients with diagnoses of hysteria. Indeed, several studies have reported rates of misdiagnosis of between 0% and 4% in regional and tertiary neurological centers,16 which suggests that a diagnosis of conversion disorder can be made relatively confidently and accurately. In the following section, the process of diagnosis is briefly outlined through the history, examination, and investigation.
The History
Previous Unexplained Symptoms.
There is accumulating evidence that the more unexplained symptoms the patient has, the more likely the primary symptom is to be unexplained.17 In one study of patients with medically unexplained motor symptoms, additional unexplained symptoms, including paresthesia (65%), pseudo-epileptic seizures (23%), and memory impairment (20%), were reported.18 It is, therefore, often useful when conversion disorder is being considered as a diagnosis to obtain a printout of the patient’s history from the primary care physician. This may reveal repeated presentations to different specialists, as well as a history of repeated surgical procedures, particularly without clear evidence of pathology.
Psychiatric Comorbidity.
Rates of depression (38% to 50%) and anxiety (10% to 16%) have been identified in a number of studies. In one small prospective controlled study, there was a fourfold increase in depression among patients with conversion disorder in comparison with matched controls with similar organic disability.19
Recent Life Events or Difficulties.
An increased number of life events in the year preceding symptom onset have been recorded in small controlled studies of unexplained motor symptoms20 and pseudoseizures.21 More recent evidence suggests that when patients are interviewed carefully, some report symptoms of panic just before the onset of, for example, functional weakness (J. Stone, personal communication, 10.2.2006). Judicious questions about sensations of sweating, dizziness, and breathing difficulty may reveal these somatic symptoms of anxiety, which may also be reported before the onset of sensory symptoms (see later section on sensory symptoms).
Secondary Gain/Litigation.
This is a complex issue, but impending litigation has been described in a number of studies of patients with unexplained motor symptoms and tremor.18,21
Neurological Comorbidity.
In one study in the United Kingdom, 42% of patients with unexplained motor symptoms had a comorbid neurological disease and, interestingly, one half of these had a peripheral origin.18 Epilepsy is believed to coexist in a significant percentage of patients with nonepileptic seizures.22
History from Relative/Informant.
There is a considerable amount of evidence to suggest that the observations and attitudes of caretakers may be important in the perpetuation of medically unexplained symptoms, especially motor conversion symptoms. For example, Davison and associates23 found caretakers to be ill informed and dissatisfied with the advice they had received from doctors about their relatives’ diagnosis and disabilities.
The Examination and Diagnostic Discrepancies
Give-way weakness is often used as a diagnostic test of hysterical paralyses, but it is unreliable. Unilateral functional weakness of a leg, if severe, tends to produce a characteristic gait in which the leg is dragged behind the body as a single unit, like a sack of potatoes. The hip is either held in external or internal rotation so that the foot points inward or outward. The most impressive quantitative discrimination to date between hysterical and neurological weakness is reported in a study of Hoover’s sign—the involuntary extension of hysterically paralyzed leg when the “good leg” is flexing against resistance. Ziv and colleagues24 demonstrated a clear difference in the pattern of response between neurological and psychogenic patient groups. It should be borne in mind, however, that the patient may have both a functional disorder and an organic disorder.25
Individual Symptoms
Paralyses
Hysterical paraplegia has been described,26 and both spinal and orthopedic surgeons, as well as rehabilitation specialists and neurologists, should be alert to the development of this disorder in their patients.27 These patients have the potential to use considerable health care resources.28
Abnormal Movements
Psychogenic movement disorders are believed to account for 1 per 30 patients attending a movement disorder clinic21 and have been the subject of a book.29 Since the mid-1980s, a number of case series of patients with psychogenic dystonia have been reported. Fahn and Williams30 described 21 cases in 1988, and Lang31 subsequently described 18 more. Clinical features that suggest a psychogenic movement disorder are shown in Table 20-3.
TABLE 20-3 Features Suggestive of a Psychogenic Movement Disorder
Adapted from Fahn S: Psychogenic movement disorders. In Marsden CD, Fahn S, eds: Movement Disorders: 3. Oxford, UK: Butterworth-Heinemann, 1995, pp 359-372.
