[Assessing the function of patients with consciousness disorders using evoked potentials].
Multimodal evoked potentials (long latency somatosensory and visual evoked potentials, brainstem auditory evoked potentials) were performed in comatose patients. For the long-latency EP-components a signal-to-noise ratio (SNR) was calculated (SNR is defined as ratio of the largest EP-peak-to-peak amplitude and the mean amplitude of a period prior to the stimulation). An unmeasurable or questionable EP was defined when SNR less than 2.6. The highest correlation (r = 0.72) was found between the clinical state, represented by Glasgow Coma Score, and the SEP. The long latency SEPs appeared as a sensitive parameter in postacute states of brain disorders. The vertex VEP had a similar correlation (r = 0.66) to the clinical state; the occipital VEP showed no correlation. Emergency from coma and recovery was accompanied by an increasing spread of the VEP over the whole scalp. The use of auditory brainstem evoked potentials in coma and brain death ist demonstrated; applications and problems are discussed.