Abstracts

Rationale: Neuropsychologists often include objective personality assessment as part of their evaluation of patients in Epilepsy Monitoring Unit (EMU) settings. Two commonly used instruments are the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) and Personality Assessment Inventory (PAI), but little research has directly compared the utility of these two measures in differentiating between patients with epileptic seizures (ES) and psychogenic nonepileptic seizures (PNES). Methods: Patients being seen for neuropsychological evaluation as part of their work-up at Mayo Clinic Arizona’s EMU were invited to participate in this prospective study. Participants were randomized to complete either the MMPI-2 (n=27) or the PAI (n=30) based on whether they had an even or odd medical record number. Their neurological discharge diagnosis of ES (n=33) or PNES (n=24) was determined by the unit’s attending epileptologist based on video-EEG review of their habitual events. Excluded were patients whose EMU admission was inconclusive or suggested physiological NES (e.g., migraine; n=19), those with diagnoses of both ES and PNES (n=1), and those whose objective personality test results were invalid due to inconsistent responding (n=1). MMPI-2 profiles were classified as suggestive of PNES if they met Wilkus et al.’s (1984) decision rules (with modifications described by Cragar et al., 2003). The criteria suggested by Wagner et al. (2005) and Stroup et al. (2006) were used to identify PAI profiles consistent with PNES. Results: In this sample, 42% of participants were diagnosed with PNES at discharge. The three classification techniques’ positive predictive power (PPP), negative predictive power (NPP), sensitivity, and specific for identifying the cases of PNES are outlined in the following table. Conclusions: Of the three personality assessment methods compared, Stroup et al.’s (2006) PAI criteria appeared to yield the best PPP; 73% of participants meeting their criteria were ultimately diagnosed with PNES. The NPP of the Stroup et al. (2006) PAI criteria and Wilkus et al. (1984) MMPI-2 decision rules was quite high in this sample, with at least 90% of those with negative personality test results not having PNES. REFERENCES Cragar, DE, Schmitt, FA, Berry, DTR, Cibula, JE, Dearth, CMS, Gakhoury, TA (2003). A comparison of MMPI-2 decision rules in the diagnosis of nonepileptic seizures. J Clin Exp Neuropsychol 25:793-804. Stroup, ES, Chaytor, NS, Drane, DL, Coady, EL, & Hosman (2006). PAI vs. MMPI in the classification of patients with epileptic and psychogenic nonepileptic seizures: Overall accuracy and advantages [Abstract]. J Int Neuropsychol Soc 12(S1):92. Wagner, MT, Wymer, JH, Topping, KB, Pritchard, PB (2005). Use of the Personality Assessment Inventory as an efficacious and cost-effective diagnostic tool for nonepileptic seizures. Epilepsy Behav 7:301-304. Wilkus, RJ, Dodrill, CB, Thompson, PM (1984). Intensive EEG monitoring and psychological studies of patients with pseudoepileptic seizures. Epilepsia 25:100-107.