OBJECTIVE: The diagnosis and classification of epilepsy often relies upon the demonstration of interictal epileptiform discharges (IEDs). Routine 20-min EEG recording has low sensitivity, with multiple EEGs increasing sensitivity to a maximum of 77% (Doppelbauer et al., 1993). An alternate strategy is the use of prolonged continuous EEG; however, there are no data on the average latency to first IED with ambulatory monitoring. METHODS: In this retrospective study we reviewed 180 consecutive patients with epilepsy referred to a Specialist Epilepsy Unit who had undergone 96h outpatient ambulatory EEGs, without medication withdrawal, where IEDs were recorded. Latency to, and factors affecting first IED were analysed. RESULTS: Median latency to first IED was 316min, (interquartile range 70-772min, n=180). IEDs were recorded in 44% of patients within 4h, 58% within 8h, 85% within 24h and 95% within 48h. Recording for the full 96h period revealed only 5% further IEDs. Multivariate analysis showed the latencies to IEDs with generalised epilepsies were shorter than with focal epilepsies (p<0.0001). CONCLUSIONS: In 95% of patients showing scalp IEDs a 48h recording was sufficient for electro-clinical classification in this study. SIGNIFICANCE: Our data are the first to show the latency to recording interictal epileptiform discharges with prolonged outpatient EEG monitoring. These data are important in guiding diagnostic practice in Specialist Epilepsy Services.
AD - Comprehensive Epilepsy Service, Royal Prince Alfred Hospital and The University of Sydney, Camperdown, Sydney, NSW 2050, Australia; Department of Neurology, North Bristol NHS Trust, Frenchay Hospital, Bristol, BS16 1LE, UK. AN - 22621908 BT - Clinical Neurophysiology DA - 241911629202 DP - NLM ET - 2012/05/25 LA - eng M1 - 9 N1 - Faulkner, Howard JArima, HisatomiMohamed, ArminNetherlandsClin Neurophysiol. 2012 Sep;123(9):1732-5. Epub 2012 May 22. N2 -OBJECTIVE: The diagnosis and classification of epilepsy often relies upon the demonstration of interictal epileptiform discharges (IEDs). Routine 20-min EEG recording has low sensitivity, with multiple EEGs increasing sensitivity to a maximum of 77% (Doppelbauer et al., 1993). An alternate strategy is the use of prolonged continuous EEG; however, there are no data on the average latency to first IED with ambulatory monitoring. METHODS: In this retrospective study we reviewed 180 consecutive patients with epilepsy referred to a Specialist Epilepsy Unit who had undergone 96h outpatient ambulatory EEGs, without medication withdrawal, where IEDs were recorded. Latency to, and factors affecting first IED were analysed. RESULTS: Median latency to first IED was 316min, (interquartile range 70-772min, n=180). IEDs were recorded in 44% of patients within 4h, 58% within 8h, 85% within 24h and 95% within 48h. Recording for the full 96h period revealed only 5% further IEDs. Multivariate analysis showed the latencies to IEDs with generalised epilepsies were shorter than with focal epilepsies (p<0.0001). CONCLUSIONS: In 95% of patients showing scalp IEDs a 48h recording was sufficient for electro-clinical classification in this study. SIGNIFICANCE: Our data are the first to show the latency to recording interictal epileptiform discharges with prolonged outpatient EEG monitoring. These data are important in guiding diagnostic practice in Specialist Epilepsy Services.
PY - 2012 SN - 1872-8952 (Electronic)1388-2457 (Linking) SP - 1732 EP - 5 T2 - Clinical Neurophysiology TI - Latency to first interictal epileptiform discharge in epilepsy with outpatient ambulatory EEG VL - 123 ER -