Preventable Sternocleidomastoid Muscular Atrophy after Neck Dissection

Area of Science:

• Head and Neck Surgery
• Surgical Oncology
• Anatomy

Background:

• Modified radical neck dissection (mRND) and supraomohyoid neck dissection are standard procedures for head and neck cancers.
• These procedures can lead to significant postoperative sternocleidomastoid muscle (SCM) atrophy and neck asymmetry.

Purpose of the Study:

• To evaluate the impact of spinal accessory nerve preservation on SCM cross-sectional area and neck asymmetry after neck dissection.
• To determine the effectiveness of nerve repair in mitigating asymmetry.

Main Methods:

• Computed tomographic (CT) imaging was used to measure SCM cross-sectional areas in 99 oral cavity cancer patients.
• An asymmetry index was calculated to quantify neck asymmetry post-surgery.
• Surgical techniques involved unilateral mRND or supraomohyoid neck dissection, with varying degrees of spinal accessory nerve preservation or sacrifice.

Main Results:

• Sacrificing spinal accessory nerve innervation resulted in extremely severe neck asymmetry.
• Repairing the nerve prevented severe asymmetry in 40% of cases.
• Preserving innervation prevented severe asymmetry in 75% of the middle neck portion and 56% of the lower neck portion.

Conclusions:

• Preserving spinal accessory nerve innervation is crucial for preventing severe neck asymmetry after neck dissection.
• Gentle handling of the spinal accessory nerve during surgery is recommended to minimize postoperative deformity.
• Nerve repair can partially restore function and reduce asymmetry, but preservation is superior.