# Neutral Position or Contralateral Head Rotation in Vagus Nerve Stimulation Surgery: A Study of Surgical Pathway and Nervus Vagus Position with Peroperative Ultrasonography

## TL;DR

This study examines how head position affects the surgical pathway and positioning of the vagus nerve during surgery, using ultrasonography to guide optimal positioning.

## Contribution

The study introduces the use of peroperative ultrasonography to determine optimal head positioning for vagus nerve stimulation surgery.

## Key findings

- SCM muscle position changes significantly with head rotation, affecting the surgical path.
- Vagus nerve position remains relatively stable despite head rotation.
- Using ultrasonography to guide head position may reduce surgical time and complications.

## Abstract

Background and Objectives: This study aimed to discuss positional changes in the sternocleidomastoid (SCM) muscle and vagus nerve with head position, their effect on the surgical path, positional variations, the selection of an appropriate position for surgery, their effects on the surgical procedure, and complications by using peroperative ultrasonography. Materials and Methods: Vagal nerve stimulation surgery patients over the age of 18 years were included. Peroperative ultrasonography images were scanned, and changes in head position and anatomical and positional variations in the SCM muscle and vagus nerve at the surgical incision level were examined. Results: SCM localization was most frequently observed in the lateral aspect of the carotid sheath (n:16) in neutral position, while it was mostly observed in the medial aspect of the carotid sheath (n:16) at a 15 degree rotation. The vagus nerve was mostly observed between the jugular vein and carotid artery in neutral position (n:21), and it was observed at the same position at a 15 degree rotation (n:17). The positional change of the SCM muscle with head position was found to be statistically significant (p < 0.001), while the positional change of the vagus nerve was not (p:0.198). Conclusions: The SCM muscle closes the surgical path with head rotation by either deviating over the carotid sheath or increasing its deviation. In addition to its anatomical variations, the vagus nerve shows different positional changes with head rotation. Deciding on the head position in vagal nerve stimulation surgery, using peroperative ultrasonography rather than a routine position, may be effective in reducing surgical time and possible complications.