[Conversion disorders. From neurobiology to treatment]

The two international systems of diagnostic classification for psychiatric disorders, ICD-10 and DSM-IV, differentiate a variety of disorders or syndromes characterized by the common feature of the presence of physical symptoms without "organic correlate." Conversion disorders (DSM) or dissociative disorders (ICD) are historically related to the concept of hysteria. Like psychoanalytical theories, the DSM and ICD refer to a psychological conflict preceding the onset of physical symptoms, although in a purely descriptive manner. The etiology of these disorders is still not very well understood. This article summarizes present knowledge from clinical and epidemiological studies. Functional neuroimaging studies on conversion disorders, although still very rare, allow testing of hypotheses about neuronal mechanisms. Such studies question the traditional and often misinterpreted dichotomy between organic and psychogenic diseases.

Motor conversion disorders reviewed from a neuropsychiatric perspective

BACKGROUND

Conversion disorder is a somatoform disorder defined by the presence of pseudoneurologic symptoms relating to voluntary sensory or motor function. The correct diagnosis of conversion disorder presenting with motor symptoms is complicated by the lack of gold-standard diagnostic tests and the absence of a universally accepted set of positive diagnostic criteria. This article reviews the epidemiology, pathophysiology, presentation, differential diagnosis, treatment, and prognosis of motor conversion, placing emphasis on diagnostic validity, reliability, and utility, while evaluating the empirical evidence supporting diagnostic and treatment strategies.

DATA SOURCES AND STUDY SELECTION

Literature searches were carried out in PubMed using the keywords conversion disorder, motor conversion, dystonia, psychogenic, hysteria, somatization, motion disorder, movement disorder, and patho-physiology. Articles and book chapters in the author's personal collection were also utilized.

CONCLUSIONS

Advances in neuropsychiatric research are leading to significant improvements in the diagnosis and understanding of motor conversion disorders. Positive, objective, and quantitative diagnostic criteria show significant promise for enhancing diagnostic accuracy. Current pathophysiologic research has begun to provide mechanistic explanations for conversion symptoms, thus blurring the distinction between psychogenic and organic motor disorders.

Functional magnetic resonance imaging of the cerebral response to visual stimulation in medically unexplained visual loss

BACKGROUND

Medically unexplained visual loss occurs in 1 to 5% of patients attending ophthalmology clinics and for many it runs a chronic course. A psychogenic aetiology is presumed in such cases, but little is known about the underlying neural mechanisms. Recent studies have established the value of functional magnetic resonance imaging (fMRI) in understanding the mechanisms of unexplained motor and sensory symptoms. The purpose of this study was to use a similar strategy (fMRI) to evaluate the cerebral responses to visual stimulation in a group of patients with medically unexplained visual loss, in an attempt to determine the underlying neural mechanisms.

METHOD

Brain activation induced by periodic (monocular) 8 Hz visual stimulation was detected by fMRI in five patients with unexplained visual loss who fulfilled DSM-IV criteria for conversion disorder, and seven normal volunteers. Between-group differences in mean power of activation were estimated by fitting a one-way analysis of variance (ANOVA) model at each intracerebral voxel in standard space.

RESULTS

Compared with controls, patients showed reduced activation in visual cortices, but increased activation in left inferior frontal cortex, left insula-claustrum, bilateral striatum and thalami, left limbic structures, and left posterior cingulate cortex.

CONCLUSIONS

This preliminary study has identified novel neural correlates in patients with unexplained visual loss. The abnormal pattern of activation may reflect inhibition of primary visual cortex or a shift towards non-conscious (implicit) processing.

Functional neuroimaging of psychiatric disorders: exploring hidden behaviour

From the outset, people have had high expectations of functional neuroimaging. Many will have been disappointed. After roughly a decade of widespread use, even an enthusiastic advocate must be diffident about the impact of the two most frequently used techniques – positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) – upon clinical psychiatry. Perhaps this disappointment arises from an unrealistic expectation of what these techniques are able to tell us about the workings of the normal and the disordered brain. Anyone who hoped for intricate and unambiguous region-to-function mapping was always going to be disappointed. This expectation presupposes, among other things, a thorough understanding of the cognitive functions that are to be mapped onto the brain regions. This understanding, however, while developing, is still rudimentary. Mapping disorder along comparable lines is even more complex since it demands two levels of understanding. The first is of the healthy region-to-function mapping, the second of the disordered region-to-function mapping, which immediately demands a consideration of the nature of the function in the disordered state. After all, someone with schizophrenia, when confronted with a psychological task, might tackle it in a very different way, in terms of the cognitive strategies used, from a healthy person confronted with the same task. The observation that brain activity differs across the two individuals would only be interpretable insofar as one thoroughly understood the processes that each individual invoked in response to the task demands.

Abnormal somatosensory evoked potentials in two patients with conversion disorder

On clinical grounds, somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) are currently used to discriminate between hysterical and neurological conditions. The present paper reports on two patients with severe gait disturbance who had the near-total absence of SEP responses on the scalp during the symptomatic period, which normalized after recovery. These findings, along with others, may shed light on the brain correlates of conversion phenomena.

Conversion disorder mimicking Dejerine-Roussy syndrome (thalamic stroke) after spinal cord stimulation

OBJECTIVE

Dejerine-Roussy syndrome is a complex of various signs and symptoms in patients suffering from central thalamic pain, usually secondary to a vascular etiology. We describe a patient presenting with the potentially devastating signs and symptoms of thalamic stroke, at least temporally related to spinal cord stimulator implantation. The etiology of the patient's affliction was subsequently revealed to be a conversion disorder. Case report A 37-year-old woman presented for spinal cord stimulation as treatment of her brachial plexopathy after failure of conservative therapy. Before implantation, she underwent a clinical interview with a psychologist and psychometric testing. No psychological pathology was detected. Trial and permanent implantation of the cervical stimulator lead and pulse generator were uneventful. Eleven days after receiving the permanent implant, the patient experienced right-sided hemicorporal numbness and burning dysesthesia. The patient was admitted, and a diagnosis of Dejerine-Roussy syndrome (thalamic stroke) was made. She was discharged, and her symptomatology waxed and waned over a period of weeks. The patient was subsequently admitted for psychiatric evaluation because of anxiety attacks. During her protracted admission, her psychiatrists strongly suspected a conversion disorder. The stimulator was removed, and the patient received supportive care only. Within 6 months, sensory symptoms and all motor deficits had completely resolved.

CONCLUSIONS

Despite careful preoperative evaluation, latent psychosocial issues may limit the effectiveness of spinal cord stimulation. We present a case of conversion disorder masquerading as Dejerine-Roussy syndrome after spinal cord stimulation. The implications of the failure of preoperative psychological evaluation and screening to avert implantation are discussed.

Somatization and conversion disorder

Somatization is the psychological mechanism whereby psychological distress is expressed in the form of physical symptoms. The psychological distress in somatization is most commonly caused by a mood disorder that threatens mental stability. Conversion disorder occurs when the somatic presentation involves any aspect of the central nervous system over which voluntary control is exercised. Conversion reactions represent fixed ideas about neurologic malfunction that are consciously enacted, resulting in psychogenic neurologic deficits. Treatment is complex and lengthy; it includes recovery of neurologic function aided by narcoanalysis and identification and treatment of the primary psychiatric disorder, usually a mood disorder.

Cognitive behavioural and neuropsychiatric treatment of post‐traumatic conversion disorder: a case study

Conversion disorder consists of involuntary sensory or motor symptoms and deficits that cannot be explained by a general medical condition. There are several treatment options, although none has emerged as the treatment of choice. The present case study examined the effects of adding cognitive behaviour therapy to neuropsychiatric management of conversion disorder (motor subtype). The patient, a retired emergency services worker, presented with a history of intermittent episodes of speech disruption (inability to speak or difficulty speaking properly). Although episodes of speech disturbance sometimes occurred unexpectedly, they were more likely to occur under conditions of stress and fatigue, and were triggered by reminders of work-related traumatic events. The patient was treated with pharmacotherapy and psychoeducation from a neuropsychiatrist. With the aim of improving treatment outcome, cognitive behaviour therapy was added, involving imaginal exposure to trauma memories, along with cognitive restructuring. The frequency of between- and within-session speech disturbance episodes declined over the course of cognitive behaviour therapy to the point that the patient was essentially symptom-free. Within-session distress ratings also decreased, which suggested habituation to trauma-related memories. This case study demonstrates how particular cognitive behaviour therapy interventions can be usefully applied to one form of conversion disorder.

Neurological associations of absent P60 component of the posterior tibial nerve somatosensory evoked potential

The cortically generated P60 component of the posterior tibial nerve somatosensory evoked potential (PTSEP) is occasionally found to be absent in neurological patients,while the preceding P40 is preserved ("Absent P60" pattern). A retrospective analysis of 24 such cases showed them to represent a different clinical population from that represented by 24 age- and sex-matched but otherwise unselected patients with entirely normal PTSEPs. The most frequent diagnoses of the patients with normal PTSEPs (conversion disorder and definite or suspected multiple sclerosis) were significantly less prevalent in the patients with the Absent P60 pattern, while miscellaneous other diseases affecting the peripheral and/or central sensory pathways were more frequent. In comparison with a second matched patient group with abnormal P40 in addition to P60, the patients with the Absent P60 pattern had a significantly lower incidence of "large fibre" sensory deficits (impaired vibration and/or joint-position sense). The incidence of "small fibre" deficits (impaired pain and/or temperature sensation) was similar in both groups with PTSEP changes. In conjunction with previously published findings in normal subjects, the data suggest that the P60 is a late response of the primary sensorimotor cortex due to activation of large diameter myelinated sensory fibres, but which is also tonically influenced by small fibre input. The Absent P60 pattern may be recognized as a distinct PTSEP abnormality, although its occurrence in some normal individuals should be noted.

Altered central somatosensory processing in chronic pain patients with "hysterical" anesthesia

OBJECTIVE

The authors hypothesized that central factors may underlie sensory deficits in patients with nondermatomal somatosensory deficits (NDSD) and that functional brain imaging would reveal altered responses in supraspinal nuclei.

BACKGROUND

Patients with chronic pain frequently present with NDSD, ranging from hypoesthesia to complete anesthesia in the absence of substantial pathology and often in association with motor weakness and occasional paralysis. Patients with pain and such pseudoneurologic symptoms can be classified as having both a pain disorder and a conversion disorder (Diagnostic and Statistical Manual of Mental Disorders-IV classification).

METHODS

The authors tested their hypothesis with functional MRI (fMRI) of brush and noxious stimulation-evoked brain responses in four patients with chronic pain and NDSD.

RESULTS

The fMRI findings revealed altered somatosensory-evoked responses in specific forebrain areas. Unperceived stimuli failed to activate areas that were activated with perceived touch and pain: notably, the thalamus, posterior region of the anterior cingulate cortex (ACC), and Brodmann area 44/45. Furthermore, unperceived stimuli were associated with deactivations in primary and secondary somatosensory cortex (S1, S2), posterior parietal cortex, and prefrontal cortex. Finally, unperceived (but not perceived) stimuli activated the rostral ACC.

CONCLUSIONS

Diminished perception of innocuous and noxious stimuli is associated with altered activity in many parts of the somatosensory pathway or other supraspinal areas. The cortical findings indicate a neurobiological component for at least part of the symptoms in patients presenting with nondermatomal somatosensory deficits.

The 12 year prognosis of unilateral functional weakness and sensory disturbance

BACKGROUND

Although the symptoms of unilateral "medically unexplained" or "functional" weakness and sensory disturbance present commonly to neurologists, little is known about their long term prognosis.

OBJECTIVE

To determine the long term outcome of functional weakness and sensory disturbance.

PATIENTS

A previously assembled cohort of 60 patients seen as inpatients by consultant neurologists in Edinburgh between 1985 and 1992 and diagnosed as having unilateral functional weakness or sensory disturbance.

METHODS

Current symptoms, disability, and distress were assessed by postal questionnaire to the patients and their family doctors.

RESULTS

Follow up data relating to mortality were obtained in 56 patients (93%) and to current diagnosis in 48 patients (80%). Patient questionnaire data were obtained in 42 patients (70%). The median duration of follow up was 12.5 years (range 9 to 16). Thirty five of the 42 patients (83%) still reported weakness or sensory symptoms, and the majority reported limitation of physical function, distress, and multiple other somatic symptoms. Twenty nine per cent had taken medical retirement. An examination of baseline predictors indicated that patients who had sensory symptoms had better functioning at follow up than those who had weakness. Only one patient had developed a neurological disorder which, in hindsight, explained the original presentation. Another patient had died of unrelated causes.

CONCLUSIONS

Many patients assessed by neurologists with unilateral functional weakness and sensory symptoms as inpatients remain symptomatic, distressed, and disabled as long as 12 years after the original diagnosis. These symptoms are only rarely explained by the subsequent development of a recognisable neurological disorder in the long term.

Psychogenic, nonepileptic seizures associated with video-EEG-verified sleep

PURPOSE

Nonepileptic seizures (NES) are expressions of a psychiatric disease state, usually conversion disorder, that mimic epileptic seizures (ES) but are not associated with the neurophysiologic changes of epilepsy. Conversion has not been demonstrated to emerge from the sleeping state. Emergence out of sleep is usually considered a virtual exclusion criterion for NES, signifying the presence instead of ES. We sought to test this hypothesis.

METHODS

We retrospectively reviewed the video-EEG of all patients admitted to our epilepsy unit over a 3-year period, who were suspected of manifesting NES. We examined the relation between NES and the patients' sleep/wake state in this cohort. Two epileptologists blindly reviewed an intermixture of cases suspected to represent NES emerging out of sleep, together with control cases. Classification of each case was made independently.

RESULTS

We found that in a small minority of patients (<1%), NES began either while the patient was sleeping, or within several seconds of arousal, well before a plan to simulate a seizure could likely have been formulated in the wakeful state.

CONCLUSIONS

In some cases, NES are not the product of the awake mind, but rather represent a psychiatric condition that can be manifest in sleep.

Conversion disorder and its subtypes: a need for a reclassification

Four subtypes of conversion disorder were described in DSM-IV. There are few publications concerning studies aimed at separating the subtypes of the conversion disorder. Usually, pseudoseizures are in focus and attempts are made to differentiate these seizures from other disorders. The aim of the present study has been to investigate differences between the four subtypes of the conversion disorder and to discuss the possibilities for a reclassification. Ninety-five patients were seen by two researchers and diagnosed as conversion disorders. The subtypes were determined according to DSM-IV criteria. All completed the Patients Information Form, developed by the researchers, and the Dissociative Experience Scale (DES). Twenty-four (25.2%) of the patients had motor symptoms or deficits (Type 1), 5 (5.2%) sensory symptoms or deficits (Type 2), 23 (24.2%) seizures or convulsions (Type 3) and 43 (47.3%) had mixed presentations (Type 4). There were statistically significant differences between the subtypes as concerns occupation, family history of psychiatric disorders, hospitalizations and place of settlement. Furthermore, the DES scores were statistically different between the groups of patients with different subtypes of conversion disorder.

Are functional motor and sensory symptoms really more frequent on the left? A systematic review

OBJECTIVES

To test the hypothesis that unilateral motor and sensory symptoms unexplained by identifiable disease are more common on the left side of the body than the right.

METHODS

Systematic review of the literature published since 1965.

RESULTS

121 eligible studies, involving 1139 patients, were analysed. The pooled proportion of functional left sided weakness and sensory symptoms in adults was 58% (95% confidence interval (CI) 55 to 61%). A much higher proportion of left sided symptoms (66%, 95% CI 61 to 71%) was found in studies where laterality featured in the title of the paper. However, when laterality was not mentioned in the title, no significant difference between left and right was observed (53% on the left, 95% CI 48 to 57%). This difference could not be explained on the basis of sex differences between the groups or the date of the study. Functional or "psychogenic" movement disorder was right sided in 68% (95% CI 61 to 75%). Handedness did not influence symptom lateralisation.

CONCLUSIONS

The findings of this systematic review question whether functional weakness and sensory symptoms do in fact occur more commonly on the left side of the body. A type of outcome variable reporting bias in combination with non-blinding of investigators may be responsible for this long held but erroneous belief.

Study on the function of pharynx & upper esophageal sphincter in globus hystericus

AIM: Globus pharyngeus is not an uncommon symptom. Presently, its unclear dated pathophysiology remains unclear and the disease can not be evaluated correctly with routine diagnostic methods. The objective of this study is to establish the normal values of pharyngeal and UES pressure, pharyngeal transit time in healthy volunteers and to compare the differences between healthy volunteers and patients with globus pharyngeus.

METHODS: Twenty-four healthy volunteers and thirty-two patients clinically diagnosed as globus pharyngeus entered the study. Pressures of pharynx and UES were measured. Pharyngeal transit time was measured by videofluoroscopic procedure.

RESULTS: Normal pressure of pharynx, and normal resting pressure of UES were 157.81 ± 63.86 mm Hg and 68.33 ± 37.56 mm Hg, respectively. The corresponding values in the patients were 175.50 ± 93.47 mm Hg and 71.38 ± 41.42 mm Hg. The pharyngeal transit time was 1.44 ± 0.30 s in normal control group, among them there were 4 cases with stasis of barium in the valleculae and one in the piriform sinus. No laryngeal penetration or aspiration was found. In the patient group, the pharyngeal transit time was 1.37 ± 0.41 s, among them there were 6 cases with stasis of barium in the valleculae and 5 in the piriform sinus. Nine cases had laryngeal penetration and 2 had aspiration. There were no statistical differences of pressures of pharynx, UES and the pharyngeal transit time between the two groups. But there was an association between laryngeal penetration and globus pharyngeus

CONCLUSION: Radiographic examination of the pharynx show specific findings of pharyngeal dysfunction in patients with globus pharyngeus. UES pressure is normal in most patients. Hence, we find no role for UES hypertonicity as an etiologic factor in globus pharyngeus.

Chicken or the egg? The biological-psychological controversy surrounding hyperemesis gravidarum

Women's somatic complaints are more likely to be labeled by physicians and other health care professionals as psychologically based when the condition has an obscure etiology. Perhaps because of this, there are a number of medical conditions which have been under investigated and where erroneous assumptions about them exist. Hyperemesis gravidarum (HG)--severe nausea and vomiting during pregnancy--is an example of such an illness. HG remains a puzzling condition for both physicians and patients because there is no known cause or cure. By its very nature, HG has a clearly established biological cause--pregnancy. Yet, because the exact causal pathophysiological mechanism is unknown, the organicity of the pregnant state is either minimized or ignored. This paper examines how HG is characterized in the literature and the empirical basis for psychogenesis. Analysis of the literature reveals a tension in the discourse such that both biologic and psychologic approaches to HG have existed in parallel tracks throughout history. Still, results support that sociocultural factors rather than scientific evidence have shaped the overarching and predominant illness paradigm of psychogenesis. Implications for women's health care and HG, in particular, are presented.

Functional weakness and sensory disturbance

In the diagnosis of functional weakness and sensory disturbance, positive physical signs are as important as absence of signs of disease. Motor signs, particularly Hoover's sign, are more reliable than sensory signs, but none should be used in isolation and must be interpreted in the overall context of the presentation. It should be borne in mind that a patient may have both a functional and an organic disorder.

Motor initiation and execution in patients with conversion paralysis

Motor initiation and motor execution in four patients with conversion paralysis were investigated in a non-affected motor modality (speech). In line with the hypothesis of dissociated control in conversion disorder [Cognit. Neuropsychiatry 8 (1) (2001) 21] motor initiation, but not response duration, was expected to be impaired. The motor initiation times (reaction time: RT) and motor execution times (response duration: RD) were compared on four RT-tasks that required the production of a verbal response: a simple choice RT-task, a mental letter rotation task, and an implicit and an explicit mental hand rotation task. Because conversion disorder is expected to primarily involve an impairment in the initiation of movement, we expected the following task characteristics to uniquely affect RT and not RD: type of instruction (implicit versus explicit instructed imagery), angle of rotation, and target arm (affected versus non-affected arm). The results indeed showed the task characteristics to significantly affect the participants' RT and not their RD. It was concluded that conversion paralysis is associated with a specific impairment in the explicit initiation of processes with a spatial and motor component.

Psychogenic sensory loss: magnetic source imaging reveals normal tactile evoked activity of the human primary and secondary somatosensory cortex

We investigated the activation of the secondary somatosensory cortex (SII) in three patients with unilateral psychogenic sensory loss in the hand. Somatosensory evoked magnetic fields were recorded in response to tactile stimulation of the index finger of the affected and the unaffected hand. Brain sources were estimated by magnetic source imaging. In all subjects, responses in both the contralateral primary somatosensory (SI) and bilateral SII areas were normal as compared with a healthy control group, irrespective of the stimulated side. The results extend previous findings of normal evoked activity in SI.

Conversion disorder in children and adolescents: a 4-year follow-up study

OBJECTIVE

To assess the outcome of conversion disorder in children and adolescents and to identify factors affecting the prognosis.

METHOD

Forty adolescents with conversion disorder were reevaluated 4 years after their initial interview. Changes in demographic and clinical data and the presence of any mood and anxiety disorders were recorded using the Structured Clinical Interview for DSM-IV Axis I Disorder (SCID-I). In addition, Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI) were applied.

RESULTS

Thirty-four patients (85%) had completely recovered from their conversion symptoms and two patients had improved (5%), whereas only four (10%) were unchanged. Fourteen (35%) patients received the diagnosis of mood and/or anxiety disorder. Favourable outcome was associated with early diagnosis (P=.04) and good premorbid adjustment (P=.01).

CONCLUSION

Conversion disorder has a favourable outcome in children and adolescents. However, mood and/or anxiety disorders are encountered at a considerable rate in these patients even after recovery from conversion symptoms. Long clinical follow-up seems appropriate in children and adolescents with conversion disorder.