Motor Innervation of the Trapezius by Cervical Sensitive Nerves: An Intraoperative Neuromonitoring Study and...

Area of Science:

• Neurosurgery
• Orthopedics
• Rehabilitation Medicine

Background:

• Cervical sensitive nerves (CSN) role in trapezius muscle innervation is not fully understood.
• Neck dissection surgery can impact shoulder and neck function.
• Investigating CSN's motor contribution is crucial for understanding post-surgical outcomes.

Purpose of the Study:

• To determine if CSN provide motor input to the trapezius muscle.
• To assess the relationship between CSN motor input and short-term functional outcomes after neck dissection.

Main Methods:

• Intraoperative stimulation of CSN roots (C2-C4) during 22 neck dissections using intraoperative neuromonitoring (IONM).
• Preservation of the spinal accessory nerve (SAN).
• Preoperative and 3-month postoperative evaluation of shoulder and neck function using goniometry, IMU-based motion analysis (iSen), trapezius strength, MCMS, and SPADI.

Main Results:

• CSN-evoked trapezius responses were observed in 45.5% of dissections.
• Significant postoperative declines in neck and shoulder range of motion and trapezius strength were noted.
• Shoulder flexion loss was significantly smaller in patients with CSN motor participation (CSN(+)) compared to those without (CSN(-)).

Conclusions:

• CSN motor input to the trapezius muscle is present in a significant portion of individuals undergoing neck dissection.
• Preservation or identification of CSN motor pathways may lead to better short-term shoulder flexion.
• Intraoperative documentation of CSN motor input could inform personalized rehabilitation strategies post-neck dissection.