A system for monitoring a patient's EEG output comprises an EEG recorder operative to generate an EEG output indicative of electrical activity produced by the brain of a patient, and an auxiliary recorder operative to generate an auxiliary output indicative of another characteristic of the patient. The auxiliary recorder may comprise a video recorder. An electronic data processor is operative to receive the EEG recorder output and the auxiliary output, the system being operative to generate synchronisation data indicative of when the EEG output and when the auxiliary output occurred with reference to a datum signal. The electronic processor is operative to process the synchronisation data to subsequently synchronise the playback of the EEG output with the auxiliary output. A compensation factor accounts for transmission latency.
