[The value of evoked potentials in the neurosurgical intensive care unit]

In the neurosurgical intensive care unit 135 patients were studied by means of multi-modality evoked potentials. The majority part of them had low scores on the Glasgow Coma Scale and a higher lever of coma according to WFNS. This fact explains the high mortality (52 per cent). These patient data were compared with the changes of evoked responses (ER) in order to learn something about the value of ER in localisation of lesions, staging, and predicting the outcome of the patients. A classification of EP alterations is introduced. There was no correlation between alteration of evoked potentials and coma stage. The analysis of latencies and inter-peak latencies revealed no correlation between comatous and alert patients. Cerebral conduction time (CCT) did not give further information. In cases of brainstem lesions the alteration of evoked responses were more marked than in the other patients. Most of the patients died who had initially marked changes in ER. The sensitivity of BAER was greater than of SSEP. A loss of response was more frequent in BAER. In deep coma stages the motor evoked responses disappeared. This fact induces problems in diagnosing brain death. Evoked potentials yield further information in patients with coma and drug therapy. They are useful in follow-ups, esp. in predicting the outcome. Evoked responses complete clinical and findings obtained via the diagnostic equipment.