041 The use of prolonged EEG recording in the diagnosis and clinical management of epilepsy

Introduction The diagnosis of epilepsy is clinical; but may be supported by EEG. Routine electroencephalogram (EEG) has a sensitivity of 50%–60%. Prolonged EEG techniques increase sensitivity, but their comparative impact on clinical management is uncertain. Aim To assess the impact of ambulatory EEG or video telemetry in patients with suspected epilepsy, by comparing the diagnosis and management before and after the investigation. Methods 104 consecutive patients, referred from 13 hospitals, underwent prolonged EEG recordings. Clinical records were assessed retrospectively for changes in either diagnosis or clinical management. Results 81/104 patients (57 females) of mean age of 38±13 years, had sufficient data for analysis. Following prolonged EEG, 44% had a change in diagnosis, 26% had EEG support for non-epileptic attack disorder (NEAD), and in 30% diagnosis was unchanged. After prolonged EEG, treatment was re-assessed in 72 patients; and changed in 47%. Diagnosis changed following ambulatory EEG (57%) as compared to video telemetry (30%). Furthermore, video telemetry confirmed NEAD in 51% of patients, whereas ambulatory EEG confirmed in only 4%. Conclusion In the majority of patients in this study, prolonged EEG recordings improved diagnostic certainty and changed clinical management. We will discuss comparative analysis of the two techniques in a blinded study, and optimising patient selection for each form of prolonged EEG monitoring.