Sternocleidomastoid Tendon as a Consistent Landmark for Identifying the Spinal Accessory Nerve: A Case Series

Objective We propose a standardized approach of using the tendon of the sternocleidomastoid (SCM) muscle to locate the spinal accessory nerve (SAN) in neck dissection. Study Design Cross-sectional anatomic study. Setting Tertiary academic medical center. Methods Adult patients aged ≥18 years undergoing primary neck dissection for head and neck cancer were included. Anatomic measurements included the length of the SCM tendon, the distance from the mastoid tip to the entrance of the SAN into the SCM, the distance from the SAN to the distal edge of the SCM tendon, and the perpendicular distance from the anterior edge of the SCM to the SAN. Five cadaveric specimens also underwent bilateral modified radical neck dissections with the same anatomic measurements taken. Results Twenty-two living subjects and 5 cadavers were included. No statistical correlation was noted between patient demographics and any measurement. The mean (SD) length of the SCM tendon was 63.7 mm (11.8) in living subjects and 61.5 mm (10.4) in cadaveric specimens. The average distance from the mastoid tip to the entrance of SAN into the SCM was 51.6 mm (12.2) in living subjects and 51.6 mm (7.1) in cadaveric subjects. The distance of the SAN insertion into the SCM muscle from the anterior edge was 8.9 mm (3.4) in living subjects and 16.2 mm (7.2) in cadaver specimens. Laterality was compared in the cadaveric specimens; there was no statistically significant difference in any of the measurements between sides. Conclusion This study demonstrates the SCM tendon to be a reliable and safe surgical landmark to identify and preserve the SAN during neck dissection.

[1]  A. George,et al.  A Novel Approach to Identifying the Spinal Accessory Nerve in Surgical Neck Dissection , 2018, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[2]  S. Lloyd.  Accessory nerve: anatomy and surgical identification. , 2007, The Journal of laryngology and otology.

[3]  A. D'cruz,et al.  A technique to identify and preserve the spinal accessory nerve during neck dissection , 2006, The Journal of Laryngology & Otology.

[4]  J. Irish,et al.  The Sternomastoid Branch of the Occipital Artery: A Surgical Landmark for the Spinal Accessory Nerve in Selective Neck Dissections , 2005, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[5]  A. Majithia,et al.  Upper neck spinal accessory nerve identification during neck dissection , 2005, The Journal of Laryngology & Otology.

[6]  M. Singer,et al.  Preservation of the Spinal Accessory Nerve in Modified Neck Dissections , 1996, The Laryngoscope.

[7]  G. Westbury,et al.  Anatomy of the accessory nerve and its cervical contributions in the neck. , 1986, Head & neck surgery.

[8]  O. Shaheen,et al.  Preservation of the accessory nerve in block dissection of the neck , 1981, The Journal of Laryngology & Otology.

[9]  W. Mullally,et al.  A syndrome resulting from radical neck dissection. , 1961, Archives of otolaryngology.

[10]  G. Crile.  Excision of Cancer of the Head and Neck: With Special Reference to the Plan of Dissection Based on One Hundred and Thirty-two Operations , 1906 .

[11]  C. Timon,et al.  Surgical landmarks of the spinal accessory nerve in modified radical neck dissection. , 2001, Clinical otolaryngology and allied sciences.