Abstracts

RATIONALE: Ambulatory Electroencephalography (AmEEG) has been available at our institution for over 5 years. To assess the value and make optimal and efficient use of this resource we undertook a prospective audit. METHODS: Unselected, consecutive cases referred to a children's hospital clinical neurophysiology department between January 1999 through March 2000 were included. An 8 channel ? ECG analogue ambulatory system (Oxford Medical) and more recently a 12 electrode looms / 11 + ECG electrode looms digital system (Micromed) was used. 54 patients (23 female) aged 1 month to 16 years were studied for 24-96 hours each. Data was collected systematically, prospectively on demographics, symptoms and reason for referral, previous EEG findings, technical recording quality and diagnostic yield. RESULTS: Symptoms or reasons for referral fell into 5 categories: were behaviours and motor attacks, including dialeptic seizures and paroxysms in sleep epileptic seizures; what was the provenance of epileptic seizures; was there electrical status in slow-wave sleep or continuous spike-wave in sleep; was a deterioration in school performance or behaviour associated with unrecognised epileptic discharge activity; was unexplained infantile apnoea epileptic? A definitive answer to the referral question was determined from 38/54 (70%) recordings. 12/38 had previous EEG evidence of epilepsy, 20/38 had previous normal or EEGs with only non-specific abnormalities, 6/38 had no available previous EEGs. In 12/38 (32%) (4/12 had normal previous interictal EEGs) epilepsy was confirmed and in 26/38 (68%) (4/26 had previous interictal epileptic EEG activity) epilepsy was thought unlikely by ambulatory ictal recording to be causing the symptoms in question. Technical failure occurred in 3/54 (5%) cases, with clear evidence of tampering in 1. CONCLUSIONS: AmEEG was found clinically useful in most cases, particularly with frequent attacks >1/24 hours, and when the family was telephoned the preceding day to confirm the current attack frequency. A diagnosis of epilepsy was often confirmed even after previous normal awake and sleep EEGs.