What stimulation rate causes at least 80% attenuation of the cortical response to posterior tibial SSEP stimulation?

The reason for selecting stimulation rates of 15 per second or higher as the correct answer lies in the nature of the cortical responses to somatosensory evoked potentials (SSEPs). When the stimulation rate exceeds 15 per second, there is a significant increase in the likelihood of temporal merging of the responses which can lead to a phenomenon known as "habituation." This physiological effect can cause a marked reduction in the amplitude of the cortical responses, frequently leading to an attenuation of at least 80%.

Neural mechanisms suggest that higher rates of stimulation may effectively reduce the ability of the neurons in the cortex to respond to each individual stimulus due to synaptic fatigue or adaptation, resulting in diminished responsiveness of the signal being measured. This response is consistent with published literature and clinical observations that indicate a specific rate threshold for consistent attenuation in the context of intraoperative monitoring.

Therefore, when it comes to intraoperative monitoring practices, recognizing this threshold is critical for accurate data interpretation and ensuring that clinicians can make effective decisions based on the dynamic changes in neural responses during surgery. Understanding the effects of stimulation parameters is crucial for the successful application of neurophysiologic monitoring techniques.