The lesser occipital nerve: A review of an often forgotten entity in head and neck surgery

Introduction: The lesser occipital nerve arises from the ventral rami of C2 and C3 and relates closely to the spinal accessory nerve along the posterior border of the sternocleidomastoid muscle. Unlike spinal accessory nerve reports of injury, attention to lesser occipital nerve causes and mechanisms of injury are uncommon, yet often result in a concern to the patient. Case Report: We present a case of a 36-year-old female with metastatic papillary thyroid carcinoma and subsequent lesser occipital nerve injury. Our objective is to review the relevant anatomical relationships, variations, and strategies to avoid injury to this often unrecognized and/or under-reported entity. Principal findings of this review demonstrate the lesser occipital nerve possesses a highly variable branching pattern, size, and sensory distribution rendering it susceptible to injury within the neck or occipital scalp. Conclusion: The close anatomic relationship of the lesser occipital nerve and spinal accessory nerve along the posterior border of the sternocleidomastoid muscle presents a “dual threat” for injury during neck dissection. Landmark-based skin incisional design and dissection has relevance to head and neck, neurosurgical/neurootologic, and facial rejuvenation surgeons. The vertical distance along the sternocleidomastoid muscle from the mastoid tip provides the most useful reference point for surgery within the neck, while the horizontal distance from mastoid tip to the external occipital protuberance provides valuable reference for occipital scalp incisions. A sub-sternocleidomastoid muscle approach, medial to lateral cervical rootlet dissection, selective judicious use of bipolar cautery, and avoidance of excessive retraction trauma, contribute to a safer surgical strategy around the lesser occipital nerve.