Abstracts

Rationale: The diagnosis of epilepsy and the classification of epilepsy syndrome are given based on the clinical evaluation. Continuous, inpatient, long-term video-EEG monitoring is widely used as a diagnostic tool for seizures and other paroxysmal events. Video-EEG helps to confirm the clinical diagnosis of the referring Physician and helps with localization of ictal onset in refractory epilepsy group (presurgical group). The purpose of this study was to analyse the change, if any, video-EEG monitoring (VEM) had on the initial referral diagnosis. Methods: A retrospective analysis of consecutive admissions to Epilepsy Monitoring Unit (EMU), at Beaumont hospital, Ireland over 24-months (2014/2015) was carried out. Referral reason and initial clinical diagnosis were recorded. Demographic data, clinical history (including early life risk factors and family history), length of stay, number of seizures, diagnosis and neuroimaging were collected from Electronic Patient Record (EPR). VEM data was analysed for clinical semiology (used ILAE classification) and ictal onset was determined. Data was recorded on Excel and standard statistical methods were used. Results: There were 367 total admissions over two year period which included 61% diagnostic referrals, 36.7% pre-surgical evaluation, 1.1% invasive EEG monitoring and was unclear in 1.1% patients. Sixty percent of patients had risk factors for epilepsy and 17% underwent previous VEM and 21 % had previous epilepsy surgery. The average length of stay was 7.2 days (ranged 1.5-26 days). The average number of events captured was 14.8 (ranging from 1-566).Both seizures and non-epileptic events were seen in 18 patients and no events recorded in 10 patients. Confirmation or change in the diagnosis (Figure 2 and Table 1): Focal epilepsy was suspected in 110 patients and was confirmed in 104 patients. Primary generalized epilepsy diagnosis was suspected in five patients but was observed in 8 patients. Non-epileptic attacks were suspected in 8 patients but noted in 31 patients. There were 29 patients without an epilepsy syndrome classification prior to VEM and this has reduced to nine (five patients had no events and four patients had events with no EEG changes). Seventy two patients were referred for discussion at National Epilepsy Surgery review meeting and 32 patients completed surgery at present. Conclusions: The main reason for referral for video-EEG at Beaumont Hospital was for diagnostic clarification including epilepsy syndrome classification followed by pre-surgical evaluation. The greatest change in the diagnosis after VEM was in the non-epileptic subgroup, 74.2% increase from preadmission diagnosis. There was also significant improvement in classifying the epilepsy syndrome and only nine patients remained unclassified after VEM. This was due to lack of EEG change with events or no events recorded. In conclusion, the video EEG monitoring in our cohort at Beaumont Hospital has been very successful in clarifying the diagnosis and allowing classification of epilepsy syndrome. The analysis of the data from 2015 is ongoing and will be completed in coming weeks. Funding: Nil