Abstracts

Rationale: EEG recordings are routinely performed to non-invasively evaluate brain electrophysiology. However, several practical and cost-related issues prevent electroencephalograms to be performed in emergency situations, battlefield or at home. Issues related to space, cost, training, and complexity of the equipment have in general hampered more widespread use of EEG. The development of simple, wireless and PC/laptop-based EEG equipment is a promising diagnostic improvement but the quality of EEG signals recorded under these conditions has not been systematically compared to routine EEG equipment. We compared the signal quality and frequency response in two systemsMethods: Wireless EEG 8- channel recording was obtained using the Crystal 20 E remote unit and software (Cleveland Medical Devices) and a Pentium IV laptop. Sampling rate was set at 300 or 600 Hz with no pre-filter settings. For hardwired EEG collection, we utilized a Nihon Kohden EEG System (Nihon Kohden, Tokyo, Japan) Nihon Kohden Neurofax EEG 9000 Version 5-72 running on a Windows XP platform using DELL Optiplex GL280. A total of 13 channels, including ground, reference, EKG, and impedance electrodes were collected. A cephalic isoground and reference was utilized for comparison of individual channels. Measurement and placement of the electrodes was done using the 10-20 system with 10-10 system measurement to approximate placement between central and temporal electrodes bilaterally to correlate to wireless 8- channel set-up. Data were viewed at low pass set at 1 Hz and high pass at 70 Hz. Results: A side-by-side comparison revealed no significant differences in overall quality of signal or frequency response in a normal subject. An example is shown in Fig.1. Conclusions: New miniature, low-cost, simple, digital, wireless EEG machines have been developed to solve several factors to allow EEG to be used in emergency departments or elsewhere to evaluate patients presenting with altered mental status, to diagnose non-convulsive seizures, etc. The 8-channel wireless EEG used in this study is feasible and provides good quality EEG signals in healthy volunteers. These signals were comparable to those recorded with more expensive traditional systems. The ability to detect subtle abnormalities including nonconvulsive status using this system will require studying a larger number of patients in the ICU setting. (Supported by NIH-NS43284, NIH-HL51614, NIH-NS46513, NIH-NS049514 and NIH-NS38195)