A comprehensive neuropsychological profile of women with psychogenic nonepileptic seizures

Abstract

The purpose of this study was to compare the neuropsychological profile of women with VEEG-confirmed diagnoses of psychogenic nonepileptic seizures (PNES) with that of an age- and education-matched group of women with left temporal lobe epilepsy (LTLE). Results indicate that in a relatively homogenous PNES sample, no severe neurocognitive impairments were present, further supporting a psychologically versus neurologically driven pathology of PNES. In comparison to age-stratified normative data, the PNES group demonstrated only a modest deficiency across neuropsychological domains and a relative area of weakness in attention and working memory, and generally outperformed their counterparts with LTLE. Although the attentional deficits in the PNES group may have been influenced by their elevated levels of emotional distress, symptoms of depression and anxiety were significant and common in both patients with PNES and those with LTLE, and therefore, the utility of psychological factors in discriminating these groups is limited. The present findings warrant the use of longitudinal research with patients with PNES to identify changes in the presentation of this condition as well as its subsequent neurocognitive and emotional impairments.

Introduction

Psychogenic nonepileptic seizures (PNES) can occur independently or in association with epileptic seizures (ES) [1], [2]. Several reviews have estimated that nonepileptic activity occurs in 5–20% of outpatients and 10–40% of inpatients referred for epilepsy evaluations [3], [4]. Although there are a variety of disparate signs and symptoms [5], [6], [7], [8], PNES episodes are most commonly characterized by a sudden and time-limited disturbance of motor, sensory, autonomic, cognitive, and/or emotional functions, and typically present as dramatic manifestations imitating epileptic complex partial episodes [9], [10]. However, unlike epileptic seizures (ES), research has shown that these psychogenic episodes are mediated by psychosocial and/or psychiatric factors [11], as there is no medical evidence of epilepsy or any other physiological condition that would result in such incidents. Moreover, research has concurred that these events are, in most cases, associated with psychopathological disorders in a broad spectrum of diagnostic categories, including both Axis I and II conditions [12], [13]. Nevertheless, a consensus regarding the nosology and psychiatric classification of PNES has not been reached [14].

The occurrence of PNES appears to peak during late adolescence and early adulthood [15], and is more commonly observed in women, with female patients constituting 75–85% of all PNES diagnoses [16], [17], [18], [19]. Research has also consistently documented elevated rates of sexual, physical, and emotional abuse histories in samples of individuals diagnosed with PNES, as well as other psychogenic disorders [20], [21]. Although both ES and PNES are chronic conditions with numerous social and psychological consequences [20], [22], PNES are considered solely psychological in nature, and thus, individuals who experience these episodes are typically referred from the medical to the psychiatry community for services [15], [23]. Given the similarities in symptomatology between PNES and ES, the gold standard for differential diagnosis has come to be video-electroencephalography (VEEG) [2], [24]. Unfortunately, however, VEEG is not readily available outside of epilepsy centers, and as a result, misdiagnosis has been extremely common and the cost has been great, resulting in barbiturate comas, unnecessary surgery, placement of vagus nerve stimulators, toxic levels of antiepileptic medications, and death [25], [26], [27]. Documenting the frequency of misdiagnosis, Reuber and colleagues found that 84% of poorly controlled or atypical seizures were, on later examination, confirmed as PNES yet had been treated with antiepileptic drugs (AEDs). Considering such dangers along with the fact that patients with PNES receiving a prompt and accurate diagnosis have demonstrated a better prognosis [28], it is imperative that researchers investigate additional and/or alternative diagnostic methods.

In an attempt to identify possible neurocognitive discrepancies associated with various seizure etiologies, the neuropsychological functioning of patients with PNES has been examined [29], [30], [31]. Among different studies, the performance of patients with PNES on measures of overall intelligence has ranged from mental retardation to superior abilities; however, a Full Scale IQ in the low average or borderline range has been documented as a frequent finding [29], [32], [33], [34]. In 2002, Cragar and colleagues reported that individuals with PNES performed poorly on objective of neurocognitive abilities measures in comparison to healthy controls. Nonetheless, the extant literature comparing the neuropsychological performance of patients with PNES and ES is riddled with disparate and conflicting results, with some research suggesting: (1) no significant differences between PNES and ES groups on measures of neurocognitive functioning [30], [35]; (2) better performance by patients with PNES compared to those with ES [16]; and (3) within individual studies, a combination of both better performance by those diagnosed with PNES and no differences between groups across different cognitive domains [36], [37], [38].

Neuropsychological research has supported a general cognitive deficit in patients with PNES, and some studies have attributed this trend to various psychological factors such as inadequate effort [16], a pessimistic attributional style [39], anxiety [40], and negative response bias [41]. Others, however, have suggested organic explanations, including a history of head trauma [20] and even hippocampal atrophy resulting from the neurochemical consequences of exposure to prolonged periods of stress [42], [43]. The lack of consensus regarding specific neuropsychological profile differences between patients with PNES and those with ES may be due in part to a number of methodological confounds, such as the recruitment of heterogeneous samples that have included both genders and mixed etiologies, as well as individuals with a history of substance abuse or head injury [29], [34], [44]. The aim of the current study was to ameliorate these issues by using a female sample with VEEG-confirmed diagnoses and excluding mixed etiologies. The purpose of this study was to illuminate the neuropsychological abilities and psychiatric characteristics of women 18 years of age and older with a VEEG-confirmed diagnosis of PNES in relation to those with left temporal lobe epilepsy (LTLE). Considering the lack of organic origin associated with PNES, it was hypothesized that those with this diagnosis would demonstrate deficits in attention and working memory, which are impairments associated with a poor mood state, as compared with age-matched normative sample data [45]. Furthermore, it was expected that the participants with LTLE would obtain lower scores on measures of verbal memory and language in comparison to those diagnosed with PNES.