Factors affecting reliability of interpretations of intra-operative evoked potentials

Objective. There are two objectives of this study. The first is to understand how practitioners of differing backgrounds approach the process of interpreting intra-operative neurophysiologic monitoring. The second is to understand whether the experience and educational background of practitioners influences the degree of agreement in their interpretations. Methods. A survey was distributed at the 2004 American Society of Neurophysiological Monitoring meeting. A total of 92 responses were obtained. The effect that various characteristics of the respondents including their experience, degree, certification and role in monitoring had on a number of outcome measures was assessed. These outcome measures included the probability that the surgeon responded to a warning, the chance that the patient would wake without a deficit after a warning was delivered, and the degree to which respondents agreed on interpretations of SSEP traces. Results. It was found that surgeons were more likely to respond to warnings issued by a monitrist with a higher degree of experience. Respondents with higher levels of experience, certification level, and degree level were more likely to agree on interpretations of evoked potential tracings. Overall, however, the degree of agreement between respondents was at most moderate. Respondents with higher levels of experience and training were more likely to provide correct answers to a subset of traces that were designed to reflect a classic pattern of change. Conclusions. This study indicates the need for additional studies on the criteria for providing warnings during IOM and the characteristics of monitrists that influence their interpretations.