Impact of neuronal cross-talk and anomalous innervation on neuromonitoring signals in head and neck surgery

Intraoperative neuromonitoring is widely utilized in head and neck surgery to identify and preserve the recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN) during thyroid and parathyroid procedures. However, anatomical variations and neuronal cross-talk can complicate the interpretation of electrophysiological signals, leading to false-positive or false-negative intraoperative feedback. This narrative review evaluates literature from PubMed and Google Scholar regarding the characteristics of the non-recurrent laryngeal nerve (NRLN), laryngeal anastomotic networks (e.g., anastomosis of Galen), and sympathetic-vagal communications. The reviewed literature indicates that structural neural variations alter standard electromyographic profiles. Specifically, the NRLN frequently exhibits a shortened latency during proximal vagal stimulation due to its altered anatomical trajectory. Furthermore, neural cross-talk between the SLN and RLN via the anastomosis of Galen may produce compensatory compound muscle action potentials, potentially masking distal focal nerve injuries. Inadvertent stimulation of the cervical sympathetic trunk mimics vagal signals, presenting as atypical waveforms with variable stimulation thresholds and morphological stability. Understanding these electrophysiological features is essential for accurate intraoperative decision-making. Careful observation of latency shifts, waveform morphology, and stimulation thresholds, when integrated into standardized monitoring protocols, assists in mitigating risks associated with neural variations.