Abstracts

Rationale: Although patients with a “dual diagnosis” of epilepsy and psychogenic non-epileptic seizures (PNES) are frequently encountered in clinical practice, common underlying features of this uniquely challenging population remain poorly understood. It is well established that the semiology of epileptic and psychogenic non-epileptic seizures (NES) differs, however few studies have characterized event semiology among patients in whom both seizure types coexist. Careful analysis of video EEG data is needed to determine whether semiology differs for each seizure type within a given patient. The present study aims to determine the extent to which event semiology may be used as an early diagnostic tool by analyzing ictal video EEG in patients with proven dual diagnosis.

Methods: Patients with video EEG proven diagnosis of epilepsy and NES were recruited from the Dartmouth-Hitchcock Epilepsy Database. Semiology for epileptic and NES were reviewed. Epileptic seizures were classified according to the ILAE semiology classification. The NES were classified as major motor, minor motor, and non-motor. Semiology was compared by two independent observers. In addition, clinical documentation for each patient was reviewed in order to identify age, gender, age of epilepsy and PNES onsets, risk factors, and psychiatric comorbidities. Imaging and video EEG were reviewed for electrographic seizure localization and semiology of clinical events.

Results: 29 patients with video EEG proven dual diagnosis were identified. Ages ranged from 21-73 (14 M, 15 F). 24 patients had focal epilepsy (11 temporal, 9 frontal, 4 multifocal) and 5 had idiopathic generalized epilepsy. Epileptic and PNES semiology was determined to be distinct in 25 patients and indistinguishable in 4 patients. Epileptic seizures were of shorter duration and exhibited 1-2 semiologies whereas PNES events tended to have multiple or variable semiologies and were of longer average duration. Age of epilepsy diagnosis preceded that of PNES in 27 patients (92%). 55% developed epilepsy before age 10 and 93% developed PNES after age 20. At least one psychiatric diagnosis was established in 96.6% of patients, the most common of which were depression, anxiety, and PTSD. 45% of patients reported a history of abuse (physical, sexual, or emotional).

Conclusions: The semiology of epileptic and non-epileptic seizures is distinct in the majority of patients (86%). In an overwhelming majority of patients, the diagnosis of NES followed an earlier diagnosis of epilepsy which raises concern that NES may be a rare complication of epilepsy. Rates of psychiatric disease are higher in patients with epileptic and NES compared to patients with epilepsy alone. Study limitations include the number of patients and patient demographic factors within Northern New England which may differ from other regions. Future studies that longitudinally follow cohorts of patients with dual diagnosis are needed to understand their long term seizure remission rate.

Funding: Please list any funding that was received in support of this abstract.: N/A.