Which response in the upper extremity somatosensory evoked potential (UE SSEP) is classified as a "stationary potential"?

The N13 response is classified as a "stationary potential" in the context of upper extremity somatosensory evoked potentials (UE SSEPs). Stationary potentials refer to those potentials that remain relatively stable in amplitude and latency after they have been established, indicating a consistent neural response to sensory stimuli.

In UE SSEPs, the N13 is generated at the level of the cervical spinal cord, which is essential for understanding the integrity of pathways involved in sensory transmission. It is typically considered stationary because, after it is elicited through stimulation of the median nerve, it does not show significant variation in response characteristics. This characteristic is critical for intraoperative monitoring, as it assists clinicians in determining whether sensory pathways remain intact during surgery.

This contrasts with other responses such as the N20, P14, and N18, which may not show the same level of consistency and stability associated with stationary potentials. The recognition of N13 as a stationary potential helps healthcare professionals effectively interpret the data collected during monitoring and assess patient safety during surgical procedures.