Telemetry System for Stimulation and Monitoring of Freely Moving Patients

A telemetry system is described in which the patient carries small stimulator and monitor units. Typically, the wrist is stimulated with 0.5 ms alternating pulses whose frequency and current (up to 10 mA peak) are remotely controlled by the neurophysiologist via a 20 MHz carrier. At the same time, the synchronized EEG-somatosensory evoked potential is transmitted from C2 via a 100 MHz carrier. The stimulus unit transmits a 100 MHz " flag" signal to the neurophysiologist to indicate that the patient is actually receiving a stimulus signal. Several examples are given in which latencies and amplitudes of the EEG-SEP are recorded.