Abstracts

Rationale: Nearly half of the patients admitted to our Epilepsy Monitoring Unit (EMU) are found to have psychogenic nonepileptic seizures (PNES). Prior to diagnosis, PNES patients are frequently treated with antiepileptic drugs (AEDs), often for several years. This exposes them to potential side effects and adverse reactions. We sought to determine if those patients diagnosed with PNES during their EMU admission have a different AED treatment profile than patients with epilepsy. Methods: We retrospectively reviewed 5,108 admissions to the Vanderbilt University Medical Center EMU from 2009 through 2018 and compared patient AED profiles in two primary groups. Patients in the first group had been diagnosed with only PNES epileptic seizures (ES) and patients in the second group were diagnosed with epilepsy and had only epileptic seizures recorded (ES). Patients who had both PNES and ES, PNES with interictal epileptiform discharges on EEG, other nonepileptic events, or no events were excluded from analysis. There were 779 patients found to have only ES and 761 patients found to have only PNES. Results: For patients diagnosed with PNES only, 81% were on AEDs at the time of EMU admission compared with 97% of those with ES only.  The average number of AEDs for PNES patients was 1.5 and for ES patients was 2.2.   In PNES patients, the five most common AEDs were levetiracetam (20.4%), gabapentin (11.6%), lamotrigine (11.2%), topiramate (10.9%), and clonazepam (8.1%).  The five most common AEDs used in ES patients were levetiracetam (23.1%), lamotrigine (18.9%), lacosamide (9.0%), oxcarbazepine (7.6%), and zonisamide (6.3%).  We also calculated the odds ratio (OR) for different AEDs. In PNES patients the five highest ORs were alprazolam (8.7), gabapentin (5.4), diazepam (4.8), topiramate (2.4), and clonazepam (2.1).  In ES patients the five highest ORs were phenobarbital (4.8), zonisamide (3.5), clobazam (3.0), clorazepate (2.6), and lacosamide (2.6).  Conclusions: Patients with PNES are frequently treated with antiepileptic medications prior to diagnosis that may have adverse effects on mood and cognitive function.  There are also significant differences in the AED profiles for patients diagnosed with PNES when compared to patients diagnosed with epilepsy. Funding: None