Newly presenting psychogenic nonepileptic seizures: Incidence, population characteristics, and early outcome from a prospective audit of a first seizure clinic
Research Highlights
► The incidence of psychogenic nonepileptic seizures in our population was 4.90/100,000/year, higher than in previous studies. ► Fifty percent of patients diagnosed early became spell free immediately or soon after diagnosis. ► There were high rates of psychological morbidity, medically unexplained symptoms, and economic dependence before or at the time of onset. ► Early outcome was predicted by employment status.
Introduction
Psychogenic nonepileptic seizures (PNES, pseudoseizures) may be defined as paroxysmal events that clinically resemble epileptic seizures, but are not associated with measurable alteration in brain electrical activity, and have a presumed or known psychological cause. Patients with PNES make up approximately 20% of those referred to specialist epilepsy clinics [1], but prevalence estimates vary widely from 2 to 33 per 100,000 [2]. The incidence of PNES was estimated to be 1.4/100,000/year in Iceland [3] and 3.03/100,000/year in Hamilton County, OH, USA [4]. The Icelandic study was population based, whereas the Hamilton County study was based on patients referred to a specialist center.
The prognosis for PNES is thought to be poor, with up to 75% of patients continuing to have spells long term [5], [6], [7]. In previous studies, mean delay to diagnosis was 5–7 years [8], [9], [10]. This is thought to be due to lack of awareness of PNES and limited access to diagnostic tests [9]. During the delay, most patients carry a diagnosis of epilepsy and many are on anticonvulsant medication [11]. Many have frequent emergency admissions to hospital [9] and are economically and socially dependent, remaining so after diagnosis [7]. A large proportion of patients have medically unexplained symptoms (MUS) other than PNES [12], [13]. Some data suggest that patients who present acutely to the hospital and are diagnosed quickly do well, and do so without the need for psychological intervention [6], [14], [15], [16]. It is unclear whether this is an effect of rapid diagnosis or a selection effect related to acute presentation to the hospital, as the largest published outcome studies to date [7], [17] found no relationship between diagnostic delay and outcome.
Section snippets
Methods
Our cohort consisted of all patients seen at the the Ayrshire and Arran First Seizure Clinic who had a confirmed diagnosis of PNES between 1 January 2006 and 31 December 2008. The clinic accepts primary and secondary care referrals for diagnosis of new-onset spells from an area with a base population of 367,566 (averaged over the 3 years of the study). It is the only such clinic within the catchment population. Out-of-catchment referrals were excluded. Referrals were accepted from the age of 13
Results
During the period of the study 843 patients were seen at the clinic. The diagnosis was epilepsy or unprovoked single seizure in 300 of 843 patients (35.6%) and PNES in 68 of 843 patients, or 54 of 843 patients when the diagnosis was based on simultaneous video/EEG recording. Other diagnoses (provoked seizure, vasovagal syncope, cardiac syncope, panic attack, sleep disorder, or other) were made in 475 of 843 (56.3%) patients. This gives an incidence of video/EEG-confirmed PNES of
Discussion
Although recruited differently, our present population is in most respects similar to those in other published series [5], [6], [7], [17]. The proportion of women (81.5%) is slightly higher than in most series [7]. The proportion reporting antecedent sexual abuse (20.4%) is lower than in our previous series of patients [17]. This may reflect the fact that in some patients, disclosure was delayed beyond our short follow-up period.
Our data were acquired following first presentation of PNES to
Ethical approval
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. The data presented were acquired as part of a larger prospective audit of the Ayrshire and Arran First Seizure Service. The Ayrshire and Arran Research Ethics Committee did not require us to proceed to a full ethics application, and are aware of submission of the present data for publication.
Conflict of interest statement
None of the authors has any conflict of interest to disclose.
Acknowledgment
We are grateful for the help of Eileen McCubbin, epilepsy specialist nurse, in gathering clinical data.
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