Why are preoperative baselines and SSEP values essential in Intraoperative Neurophysiologic Monitoring (IONM)?

Preoperative baselines and SSEP values are crucial in Intraoperative Neurophysiologic Monitoring (IONM) because they provide a reference point for evaluating any potential changes that occur during surgery. Establishing these values before the procedure allows the monitoring team to detect deviations that may indicate neurological compromise.

The context behind this choice lies in the fact that during surgery, various factors can influence the evoked potentials (EPs), and absolute boundaries for these values are often not defined during the intraoperative setting. This absence of predetermined thresholds makes it essential to compare intraoperative findings with the established preoperative baselines to assess alterations that might signify injury or dysfunction.

In contrast, while the appropriate level of anesthesia is significant, it is not the primary reason for using preoperative baselines for SSEPs. Additionally, the variability in latencies and amplitudes, while relevant to the overall understanding of the data, does not directly emphasize the necessity of having preoperative baselines. Lastly, although laboratory normative data is beneficial for broader comparisons, the immediate importance in IONM is primarily tied to individual patient baselines as they provide the most relevant context for intraoperative observations.