128-channel cable-telemetry EEG recording system for long-term invasive monitoring

A 128-channel cable-telemetry EEG monitoring system has been developed for use on patients undergoing intensive neurodiagnostic monitoring with invasive intracranial electrodes. A unique head mounted preamplifier/multiplexor design allows continuous recording from any combination of intracerebral, subdural, epidural or surface electrodes. A computer is used to delay or buffer all 128 channels by 2 min or more. This computer is connected to a fileserver via a local area network and is used exclusively for data acquisition. Seizure files created by the activation of the seizure/event push button or detected by a second computer containing on-line seizure/spike detection algorithms are written directly on to the fileserver by the acquisition computer. The 128 channels of EEG recorded on the fileserver can then be remotely reviewed on a high resolution graphics terminal, printed out on a laser jet printer, archived or played out on paper, 16 channels at a time on any EEG machine. A time of day signal is also generated by the computer to permit time correlation with a continuous audio/video VCR unit which permits comparison of the EEG and clinical events. This system allows continuous EEG monitoring of extensive multichannel arrays not previously possible with conventional 16-, 32- or even 64-channel systems.