Abstracts

Rationale: Obtaining emergency electroencephalograms (EEG) for the diagnosis of seizures after business hours, especially during the weekends, can create logistical problems in most hospitals. In many remote areas in some developed and most developing countries, EEGs are not available due to lack of technical manpower. We developed and explored a unique 7-electrode EEG montage as an abbreviated version of the international 10-20 system for the rapid evaluation of patients with suspected seizures in clinical situations where technician support is not available. Methods: A total of thirty one (n=31) 10-20 minute EEG samples of seizures (n=9), epileptiform discharges (n=4), generalized slowing (n=9), burst suppression (n=1), and normal studies (n=9) were remontaged to the 7 electrode - 20 channel montage (see figure 1) and were interpreted, in a blinded manner, by 2 epilepsy fellows. Their EEG interpretation was compared with the EEG interpretation made by an attending using the full 10-20 system. Results: The overall sensitivity for correct interpretation was 95.1%. The sensitivity for seizures was 83.3%, epileptiform discharges 100 %, slowing 100%, burst suppression 100% and normal studies 100% . There were 3 errors in interpretation. Once seizure was mistakening interpreted as slowing. Also, both reviewers mistakenly interpreted epileptiform discharges when there was actually a seizure. Conclusions: EEG data reformatted to the 7-electrode - 20 channel montage EEG montage had high sensitivity for detecting seizures, epileptiform discharges, diffuse slowing, and normal studies. The seven electrode montage EEG may be of clinical use as a screening tool for emergency situations and in remote areas when technical support is not readily available.