Somatization, dissociation and general psychopathology in patients with psychogenic non-epileptic seizures
Introduction
Psychogenic non-epileptic seizures (PNES) may be defined as paroxysmal behavior patterns mimicking epileptic seizures, characterized by a sudden and time-limited disturbance of motor, sensory, autonomic, cognitive and/or emotional functions, and mediated by psychosocial factors. It has been suggested that the prevalence is 2–33/100,000 (Benbadis et al., 2000), with an incidence of 4% that of epilepsy (Sigurdardottir and Olafsson, 1998). The nosology and psychiatric classification of PNES remains controversial (Martin and Gates, 2000). Important reasons for this are that patients with PNES do not fall into a single neat psychopathological category, and that the pathogenesis of PNES is unclear. In the current diagnostic systems of the DSM IV or the ICD 10, PNES are either seen as a manifestation of somatoform or dissociative disorder (American Psychiatric Association, 1994, World Health Organization, 1992).
Reasons for considering PNES as a somatoform phenomenon are that the primary characteristic seems to be a physical symptoms that suggests a general medical condition rather than a psychological disorder (American Psychiatric Association, 1994), and that PNES are often associated with other forms of somatization (Devinsky, 1998, Ford, 1993). In keeping with this, PNES patients can be differentiated from patients with epilepsy using somatization scales (Kuyk et al., 1999). In contrast, PNES have been considered as dissociative because many PNES represent a “partial or complete loss of the normal integration between memories of the part, awareness of identity and immediate sensations, and control of bodily movements” (World Health Organization, 1992), because patients with PNES share many clinical characteristics of patients with other dissociative states, especially an association with previous trauma (Bowman, 1993, Fleisher et al., 2002, Kuyk et al., 1996), and because measures of dissociation, like the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D), the Dissociative Experience Scale (DES) or its subscales have been found to be elevated in PNES groups compared to healthy individuals or patients with epilepsy (Alper et al., 1997, Bowman and Coons, 2000, Prueter et al., 2002).
No previous studies have explored the correlation between degrees of somatization or dissociation and PNES severity or outcome, although this would strengthen the clinical association or possible etiological link. Furthermore, the association between PNES severity and psychopathology has not been examined, although measures of psychopathological symptoms have also been shown to be elevated in patients with PNES or other conversion disorders compared to patients with epilepsy or non-conversion neuroses (Prueter et al., 2002, Spitzer et al., 1999). Lastly, the interaction of somatoform and dissociative tendencies with each other, and with the level of general psychopathology has not been examined in PNES, although there is evidence that somatization and dissociation are positively correlated in other patient groups (Ross et al., 1990, Saxe et al., 1994, Spitzer et al., 1999), and that dissociation scores are strongly affected by current psychopathology (Van Ijzendoorn and Schuengel, 1996).
Our examination of these issues is based on the German versions of the “Screening Test for Somatoform Symptoms-2” (SOMS), the “Dissociative Experience Scale”, and the “Symptom Checklist-90-Revised” (SCL-90-R). The SOMS is an instrument capable of screening for a DSM IV or ICD 10 diagnosis of somatization disorder, which measures the tendency to develop medically unexplained somatic symptoms in all systems of the body (Rief et al., 1997). The DES is a widely used measure of dissociative experiences ranging from absorption whilst watching a movie to amnesia for important aspects of one’s life (Bernstein and Putnam, 1986, Freyberger et al., 1999). The SCL-90-R measures a broad spectrum of psychiatric symptoms and provides a general psychopathology score (Derogatis, 1983, Franke, 1994).
We hypothesized that all measures would differentiate between patients with PNES and patients with epilepsy, that scores would be related to measures of PNES severity and outcome, and that there would be a positive correlation of dissociation, somatization and general psychopathology scores. We did not expect to find a correlation of high scores and poor outcome or greater seizure severity in patients with epilepsy.
Section snippets
Patients with PNES
The database of the Department of Epileptology, University of Bonn, Germany, was used to identify all patients in whom a diagnosis of PNES was newly established between April 1991 and April 2001 (n=329). Patients were only included if the diagnosis of PNES was secure (if typical events had been recorded using video-EEG, EEG, observation and ictal examination, or by the provocation of a typical seizure by intravenous injection of 0.9% saline). For this study, we excluded all patients with
Responders/non-responders
The response rate of PNES patients who could be contacted was 64.1%, Of the 210 patients with PNES alone, 98 returned the postal questionnaire (46.7%), 57 (27.1%) had moved and could not be traced, 4 (1.9%) did not want to take part in the study and 51 (24.3%) failed to return the questionnaire although they had received it. The response rate of contactable epilepsy patients was 71.5%. Of the 119 patients, 63 (52.9%) completed the questionnaire, 31 (26.1%) could not be traced, 4 (3.4%) had
Discussion
The mean dissociation (mDES), and general psychopathology (GSI, SCL-90-R) scores found in our patients with PNES and epilepsy were in line with previous results (Prueter et al., 2002, Spitzer et al., 1999, Van Ijzendoorn and Schuengel, 1996). The somatization (SOMS) questionnaire used here has never been applied in these patient groups before. The mean somatization scores of both groups were higher than that of the scale’s norm population (mean SIDSM 3.2, S.D. 3.2) (Rief et al., 1997). All mean
Acknowledgements
Markus Reuber was supported by the St. James’s Nervous Diseases Research Trust, the Special Trustees of the General Infirmary at Leeds, Leeds, United Kingdom, and the Stiftung für die Förderung der Epilepsieforschung, Bonn, Germany.
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