Clinical differences between patients with nonepileptic seizures who report antecedent sexual abuse and those who do not


Address correspondence to Dr. Roderick Duncan, Department of Neurology, Southern General Hospital, Glasgow G51 4TF, Scotland. E-mail:


Purpose: To investigate clinical differences between patients with psychogenic nonepileptic seizures (PNES) who report antecedent sexual abuse, and patients who do not.

Methods: In a consecutive series of 176 patients with video-EEG confirmed PNES without epilepsy, we compared patients who reported antecedent sexual abuse with those who did not report sexual abuse, in respect of a range of demographic and clinical variables.

Results: Fifty-nine women (45%) and 5 men (11%) reported sexual abuse. Those reporting sexual abuse had earlier onset PNES (28.5 vs. 33.1 years, p = 0.0319) and greater delay from onset to diagnosis (median 5.2 vs. 3.2 years, p < 0.0137). They more often drew social security benefits (p = 0.0054) and were less often in cohabiting relationships (p = 0.0006). Those who reported sexual abuse had poorer mental health on a range of indicators. Their spells were more often “convulsive” (p = 0.0419), were more severe (p = 0.0011), were more likely to have emotional triggers (p = 0.0045) and to include prodromes (p = 0.0424) and flashbacks (p < 0.0001). A history of nocturnal spells (p = 0.0109), injury during spells (p = 0.0056), and incontinence during spells (p = 0.0083) were also more common in the patients reporting sexual abuse.

Discussion: Our results suggest that patients with PNES who report sexual abuse have more severe PNES, are more likely to have PNES with features that suggest epilepsy, and are psychiatrically more unwell than those who do not report sexual abuse.

Psychogenic nonepileptic seizures (PNES, pseudoseizures) may be defined as paroxysmal events that clinically resemble epileptic seizures but that are not associated with measurable alteration in brain electrical activity, and that have a presumed or known psychological cause. Prevalence estimates vary from 2 to 33 per 100,000 (Benbadis & Allen, 2000). Patients with PNES make up approximately one quarter of those referred to specialist epilepsy clinics (Szaflarski et al., 2000).

A previous study found that in patients with late onset of PNES the most commonly reported antecedent psychological trauma was related to physical ill health, a finding with potential implications for clinical assessment and treatment (Duncan et al., 2006). In earlier onset patients in that study, the most commonly reported antecedent trauma was sexual abuse, also reported by 20–67% of patients in other published clinical samples (Betts & Boden, 1992; Alper et al., 1993; Bowman & Markand, 1993). There are problems relating to both the definition of sexual abuse and the accuracy of patient reports, and its possible role in the causation and development of PNES remains under discussion (Sharpe & Faye, 2006). As a step toward resolving some of these issues, it may be useful to determine whether populations of patients who do report sexual abuse are different from those who do not. We have therefore carried out an exploratory investigation in a large clinical cohort, comparing patients with and without a history of sexual abuse.


Our cohort consisted of a consecutive series of patients seen at the West of Scotland specialist referral center for patients with suspected PNES (catchment population 2.7 million). Between March 1999 and March 2003, 198 patients received a diagnosis of PNES, confirmed by recording typical spells with inpatient video EEG or short outpatient video EEG (McGonigal et al., 2002). Those with evidence of coexisting epilepsy (22/198) were excluded from this study.

Information was acquired using a semistructured interview with the patient and an eyewitness, usually a relative or partner. The same investigator—a physician with specialist expertise in epilepsy and PNES—carried out all assessments. Data from case records was acquired at the time of clinical assessment. The following information was recorded:

  • (a) Sociodemographic data.
  • (b) History of sexual abuse, pragmatically defined as any reported compelled act of a sexual nature perceived as abusive by the patient and occurring at any stage in life preceding the onset of PNES. Sexual abuse was reported by some patients during follow-up consultations and this was retrospectively recorded.
  • (c) A history of physical abuse, also pragmatically defined according to the patient's account and perception of the nature of the experience.
  • (d) Documented previous referral to secondary mental health services, and past psychiatric diagnoses, including a history of deliberate self-harm (suicidal or nonsuicidal), the last based on patient account and case records.
  • (e) Current or past panic attacks, documented in case notes or diagnosed according to Diagnostic and Statistical Manual of Mental Disorders (DSM) IV criteria at the time of the initial interview.
  • (f) PNES severity index on a scale of 0–5 similar to that described by Reuber et al. (2003), based on patient and eyewitness history of spells, of apparent ictal loss of consciousness, incontinence, tongue biting, self-injurious behavior during spells, and pseudostatus epilepticus.
  • (g) The clinical semiology of the PNES, based on patient and eyewitness accounts, confirmed by video EEG. Triggering factors, premonitory symptoms, flashbacks (intrusive memories of traumatic life events), and other internal experiences (e.g., images, emotions and other experiences) were documented. Spells were classified as “convulsive” if there was loss of response to surroundings with coarse or fine tremor, or similar movements. Other types (in most cases “swoon” and “pseudo absence” spells) were classified as nonconvulsive.

Statistical analysis

Patients reporting antecedent sexual abuse were compared with remaining patients. Categorical variables were compared using chi-square tests or Fisher's exact test if expected frequencies were less than 5. Relative risk (RR) and 95% confidence limits were calculated. Student's t-test was used to compare continuous variables unless Levene's test indicated deviation from normal distribution, in which case The Mann–Whitney U-test was used. Two tailed p-values are quoted in either case. As this was an exploratory study, p-values are quoted uncorrected for multiple comparisons.


Of the 176 subjects, 130 (74%) were women and 46 (26%) were men. Fifty-nine women (45%) and 5 men (11%) reported antecedent sexual abuse, while 71 women (55%) and 41 men (89%) did not (RR = 1.45, p > 0.001). Of the 64 patients who reported sexual abuse, 32 also reported physical abuse, compared to only 17 of the 112 patients not reporting sexual abuse (RR = 3.29, p < 0.001).

Associations with reported sexual abuse

Sociodemographic and clinical features are shown in Table 1. Patient age at onset of PNES was less in those reporting sexual abuse, at 28.5 ± 12.1 versus 33.1 ± 15.7 years (p = 0.0319), and patients reporting sexual abuse had a significantly longer time to diagnosis than those not, at 5.2 ± 2.1 versus 3.2 ± 1.3 years (p = 0.0137: median and interquartile range (IQR) are quoted as the data deviated significantly from a normal distribution). Those reporting sexual abuse were more often prescribed two or more antiepileptic drugs (19/64 vs. 13/112, RR = 2.56), were more often receiving state benefits (48/64 vs. 66/112, RR = 1.27), and were less often in cohabiting relationships (29/64 vs. 80/112, RR = 0.63).

Table 1.  Demographic and clinical characteristics
 Report sexual abuse (n = 64)Do not report sexual abuse (n = 112)Relative risk (95% cl)p
Female gender 59 (92.2%) 71 (63.4%)1.45 (1.24–1.70)<0.0001 
Mean age of onset of PNES (SD)28.5 (±12.1)33.1 (±15.7)N/A0.0319
Median years from onset to diagnosis (first quartile)5.2 (±2.1)3.2 (±1.3)N/A0.0137
Mean age at diagnosis (SD)37.5 (+11.0)38.5 (±16.0)N/A0.7688
On two or more antiepileptic drugs 19 (29.7%) 13 (11.6%)2.56 (1.36–4.83)0.0028
In receipt of state benefits 48 (75.0%) 66 (58.9%)1.27 (1.03–1.57)0.0054
In cohabiting relationship 29 (45.3%) 80 (71.4%)0.63 (0.47–0.85)0.0006
Physical abuse 32 (50.0%) 17 (15.2%)3.29 (1.99–5.44)<0.0001 

Data relating to mental health are shown in Table 2. Patients who reported sexual abuse were more likely to have been referred previously to secondary mental health services (51/64 vs. 44/112, RR = 2.03) and to have a history of depression (46/64 vs. 45/112, RR = 1.79) or any mental health problem (61/64 vs. 75/112, RR = 1.42). Deliberate self-harm occurred approximately four times more often in those who reported sexual abuse (34/64 vs. 14/112, RR = 4.25), who were also more likely to have a diagnosis of personality disorder (9/64 vs. 2/112, RR = 7.88). A history of medically unexplained symptoms was also more frequent in the sexually abused group (55/64 vs. 79/112, RR = 1.22). No statistically significant differences were found in regard to documented diagnoses of anxiety disorders, panic attacks, eating disorders, psychosis, or phobia.

Table 2.  Indicators of mental ill health
 Report sexual abuse (n = 64)Do not report sexual abuse (n = 112)Relative risk (95% cl)p
Previous referral to secondary mental health services51 (79.7%)44 (39.3%)2.03 (1.56–2.63)<0.0001
History of any mental health problem61 (95.3%)75 (67.0%)1.42 (1.24–1.64)<0.0001
History of depression46 (71.9%)45 (40.2%)1.79 (1.36–2.35) 0.0001
History of deliberate self-harm34 (53.1%)14 (12.5%)4.25 (2.47–7.30)<0.0001
Diagnosis of personality disorder 9 (14.1%)2 (1.8%)  7.88 (1.76 – 35.33) 0.0012
Medically unexplained symptoms55 (85.9%)79 (70.5%)1.22 (1.04–1.42) 0.0211

Semiological features of the patients' spells are shown in Table 3. Those reporting sexual abuse more often had convulsive PNES (52/64 vs. 75/112, RR = 1.21) and had higher mean severity scores (2.17 vs. 1.55). They were more likely to have emotional triggers (45/64 vs. 54/112, RR = 1.46), to experience a prodrome (41/64 vs. 54/112, RR = 1.33), and to have flashbacks (29/64 vs. 13/112, RR = 3.90) and internal experiences (18/64 vs. 16/112, RR = 1.97) in association with their spells. They were more likely to report nocturnal spells (43/64 vs. 53/112, RR = 1.42), to have self-injurious behavior (29/64 vs. 28/112, RR = 1.81) and urinary incontinence (27/64 vs. 26/112, RR = 1.82) during spells. There were no statistically significant differences between the groups in frequency and duration of spells, or in recovery time.

Table 3.  Semiology of nonepileptic spells
 Report sexual abuse (n = 64)Do not report sexual abuse (n = 112)Relative risk (95% cl)p
Convulsive spells52 (81.3%)75 (67.0%)1.21 (1.02–1.45)0.0419
Spell severity index (SD)2.17 (±1.28) 1.55 (±1.10) N/A0.0011
Emotional trigger for spells45 (70.3%)54 (48.2%)1.46 (1.14–1.87)0.0045
Prodrome before spells41 (64.1%)54 (48.2%)1.33 (1.02–1.73)0.0424
Flashbacks during spells29 (45.3%)13 (11.6%)3.90 (2.19–6.96)<0.0001 
Internal experiences during spells18 (28.1%)16 (14.3%)1.97 (1.08–3.58)0.0253
Nocturnal spells43 (67.2%)53 (47.3%)1.42 (1.09–1.84)0.0109
Self injurious behavior during spells29 (45.3%)28 (25.0%)1.81 (1.19–2.76)0.0056
Urinary incontinence during spells27 (42.2%)26 (23.2%)1.82 (1.17–2.83)0.0083


Our cohort is similar to other large series of patients with PNES, in that approximately three-quarters were women, there was coexisting epilepsy in approximately 10% of the original referrals, and 36% reported antecedent sexual abuse (Lesser et al., 1983; Meierkord et al., 1991; Betts & Boden, 1992; Alper et al., 1993; Bowman & Markand, 1993; Lesser, 1996; Benbadis et al., 2001; Reuber et al., 2002b; Martin et al., 2003).

Past research has tended to approach patients with PNES as a homogeneous group. Our previous studies (Duncan et al., 2006; Duncan & Oto, 2008) found that subgroups with late onset PNES and with learning difficulty differed significantly from the rest of the patients. The differences in the present study between those reporting and those not reporting sexual abuse provide further evidence for nonhomogeneity of PNES populations.

In previous studies as in the present one, the delay to diagnosis of PNES is approximately 7 years (Walczak et al., 1995; Selwa et al., 2000; Reuber et al., 2002a). In our patients, longer diagnostic delay was associated with sexual abuse: patients in the sexual abuse group were diagnosed after a median delay of 5.23 years as opposed to 3.23 years for those not reporting sexual abuse (for comparison purposes, the corresponding mean delays were 8.97 and 5.39 years). Delayed diagnosis has been associated with clinical factors such as incontinence, injury, and spells during sleep (De Timary et al., 2002), factors that might make the diagnosis of epilepsy more likely. All these features were more frequent in patients reporting sexual abuse in our study.

There is evidence of a modest association between sexual abuse and “convulsive” PNES in this and one previous investigation (Betts & Boden, 1992; Alper, 2000; Abubakr et al., 2003). Our index of spell severity was markedly higher in those reporting sexual abuse, and this factor combined with longer delay in diagnosis may account for the higher number of patients on multiple antiepileptic drugs. We also found significant associations between reported sexual abuse and some subjective elements of spell semiology: emotional triggers, prodromes, internal experiences, and flashbacks. Further examination is required of the relationship between flashbacks occurring in PNES, and flashbacks that are a feature of dissociative and other trauma related mental disorders (Bowman & Markand, 1996; Rosenberg et al., 2000; Reuber et al., 2003).

Our broad indicators of psychopathology and our evaluation of past abuse were based on history from the patient and, where appropriate, a relative, supplemented by examination of available case records. Patients had opportunities during follow-up sessions with the same doctor, and with a (female) psychologist, to discuss sensitive issues. However, no matter how much care is taken over ascertainment, under-reporting and over-reporting cannot be discounted. Therefore, we have been careful to base our study on “face-value” assessment of patient accounts, and on comparison between groups in a sample in which reporting of sexual abuse and other issues were subject to standard conditions and definitions. Our results should be seen in that light.

As expected, emotional disorders were frequent in our patients (Lesser, 1996), and our results suggested strikingly poorer mental health in those reporting sexual abuse; 95% had suffered some type of mental health problem other than PNES in their lifetime, and 80% had previous referrals to secondary mental health services. These results are comparable with those seen in broader populations of people with sexual abuse (Peters & Range, 1995; Romans et al., 1995; Gladstone et al., 2004), as was the finding that PNES patients reporting sexual abuse were less likely to be in cohabiting relationships (Davis & Petetric-Jackson, 2000). Features of personality disorder are known to occur in PNES populations (Reuber et al., 2004), and our findings suggest an association with sexual abuse that may warrant further study.

The psychological and psychiatric issues raised by this study require more detailed study using standardized research interviews. Also, there should be further examination of the nature and range of severity of sexual (and physical) abuse in different patients. Our findings so far suggest that patients with PNES who have been sexually abused are more psychologically unwell, are more socially disabled, and have spells that are more difficult to distinguish from epileptic seizures. This underlines the need to ensure that the assessment for abuse is carried out, and appropriate mental health support given. Eliciting some of our stronger differentiating variables may assist in the process of identifying patients at risk of having past sexual abuse.

Our data suggest that future research into PNES might usefully take into account of potential subgroup issues. In clinical practice, the subgroup of patients who have a history of sexual abuse pose particular diagnostic and treatment challenges. Poor prognosis has been found to be associated with longer delay to diagnosis (Buchanan & Snars, 1993; Walczak et al., 1995; De Timary et al., 2002; Selwa et al., 2000), poorer psychological health (Lempert & Schmidt, 1990; Buchanan & Snars, 1993; Reuber et al., 2004), and more “dramatic” spells (Reuber et al., 2003): these factors were associated with sexual abuse in the present study. Outcome studies should be able to address the question of whether sexual abuse itself is a poor prognostic factor.

Conflict of interest: The study was not funded and it was carried out with the approval of the ethics committee of the Southern General Hospital. The authors report no conflicts of interest. The authors confirm that they have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.