Abstracts

Rationale: Psychogenic non-epileptic seizures (PNES) are often mistaken for epilepsy in community practice. Inpatient video-EEG monitoring (VEEG) settles the diagnosis, but pointers to PNES in an outpatient clinical setting may help in anticipating outcome. We developed a simple score designed for use in an outpatient setting to predict the subsequent VEEG diagnosis of PNES. Methods: This was a retrospective study comparing fifty-five consecutive patients with VEEG-proven PNES (N1=55) with a group of randomly selected patients with VEEG-proven epilepsy (N2=55). All patients were drawn from GPK’s personal practice and divided into two groups: I) a ‘retrospective’ group of 27 PNES patients and 27 epilepsy patients whose data served to develop the score, and II) a ‘prospective’ group of 28 patients each with PNES and epilepsy to whom the score was applied. Unblinded review of clinical data in all Group I subjects by SR and GPK revealed six features in the history that appeared more prominent in PNES than epilepsy patients. These were assigned escalating numerical values as follows: number of declared drug allergies (0, 0.5, 1), number of declared comorbidities (0, 0.5, 1), number of previous invasive medical interventions of any type (0, 0.5, 1), and a history of significant psychological or physical trauma (0 or 1). In addition, a score was assigned to verbal description of the seizures themselves as being consistent (=0), atypical (=1) or indeterminate (=0.5) for epilepsy. The values were added to yield an omnibus score ranging from 0-4.5. The blinded author (JDS) then reviewed and scored all the Group II subject data. The mean score group difference between Group II PNES and epilepsy patients was tested for statistical significance. Results: Group II scores fell into the following categories for PNES patients. Three (10.7%) scored between 3.5-4, 12 (42.8%) between 2.5-3, 9 (32.1%) between 1.5-2, 4 (14.3%) between 0.5-1; no patient scored 0. For epilepsy patients, 0 scored between 3.5-4, 0 between 2.5-3, 4 (14.3%) between 1.5-2, 12 (42.8%) between 0.5-1 and 12 (42.8%) scored 0. In general PNES patients had higher scores and the majority obtained a score > 1.5; most epilepsy patients scored < 1.5. Group difference in the mean between the PNES and epilepsy cohort was highly significant (p < 0.0001, Wilcoxon rank-sum test). Conclusions: VEEG remains the gold standard for diagnosis of patients with paroxysmal symptoms as epilepsy, PNES, or paroxysmal spell of other cause. PNES patients score high on outpatient psychometric scales such as the Minnesota Multiphasic Personality Inventory (Wilkus et al, Epilepsia 1984;25(1):100–7); a prior history of trauma is also common in PNES (Brown & Reuber, Clin Psychol Rev 2016;45:157–82). However, none of the particular characteristics of PNES patients have been applied towards an a priori diagnosis. Our score is a simple clinical instrument based on the patient history that may predict the later confirmation of a PNES diagnosis. The results may find use in the triage of patients awaiting hospitalization for VEEG and in pre-VEEG counselling.