Interictal EEG changes in patients with seizure disorder: experience in Bangladesh.

The objective of this study was to determine the changes and sensitivity of electro encephalogram during interictal period and to evaluate the finding in the clinically suspected seizure events in a tertiary care hospital of Bangladesh. This cross sectional study was carried out in the Electrophysiology Laboratory of Dhaka Medical College Hospital from July 2010 to July 2011, which included 767 patients. EEG was obtained through scalp electrodes following international 10/20 system. Patient and their attendants were interviewed using a semi structured questionnaire. The EEG findings and clinical seizure events were then compared. Among the 767 epilepsy patients most were children (39.9% less than 10 years old) and young adult (33.2% in 11-20 years age group). Female patients predominantly had seizure than male (57% and 43% respectively). The overall sensitivity of EEG in yielding abnormal interictal epileptiform discharges was 62.7%. About 48.5% of them were diagnosed as localization related epilepsy and 11.7% were generalized epilepsy. Morphology showed spike and wave in 74% and sharp and wave in 11% tracings. Only 2% had slow waves. The presence of an interictal spike/sharp wave helps to confirm a clinical diagnosis of epilepsy, aids in defining the epilepsy syndrome, provides information that assists in planning drug management.