Abstracts

Rationale: Electroencephalograms (EEG) are routinely used to evaluate patients suspected of having symptoms consistent with new onset seizures. A recent evidence-based review showed that routine (short) EEG s obtained after new onset seizures showed some abnormalities in 12% to 73% and significantly abnormalities in 8% to 50% of the populations studied (Krumholtz et al., 2007). Whether longer initial EEG studies can enhance the detection of electrical abnormalities for new onset seizures is unclear. In this retrospective study, we evaluated patients with no past history of seizures, who presented with symptoms consistent with new onset seizures and were initially evaluated by a short (< 1 hour) EEG (sEEG) then followed by prolonged (> 1 hour) EEG (pEEG) monitoring. Methods: This was a retrospective study assessing all patients presenting to Stony Brook University Medical Center in 2010 and evaluated by EEG for symptoms consistent with new onset seizures. These patients had no past history of seizures. Patients were initially evaluated by sEEG followed shortly thereafter with pEEG either because of clinical suspicion or repeated symptoms. In total, 90 patients (children and adults) were evaluated using the following billing codes for sEEG (95812, 95816, and 95819) and for pEEG (95813 and 95951), see Figure 1. The data were qualitative in nature and reported as either normal or abnormal. Time between symptoms, sEEG and pEEG varied from hours to days. Details pertaining to age, sex, presenting symptoms and descriptive EEG abnormality are shown in Table I. Results: Our results show that 40% of our patients had a normal sEEG and normal pEEG, 37.5% had an abnormal sEEG and an abnormal pEEG, 17% had a normal sEEG and an abnormal pEEG and 5.5% had an abnormal sEEG and a normal pEEG. (Figure. 1) Conclusions: A significant population of patients who are evaluated with sEEG for new onset seizures will be misdiagnosed as normal, thus warranting pEEG.