The phrenic nerve; the forgotten nerve in head and neck surgery

Neck dissection is a commonly performed procedure for oncologic control of head and neck malignancy. With contemporary modified radical and selective neck dissections, haematoma, wound infection, tissue necrosis, chyle leak and injury involving the marginal mandibular, hypoglossal, vagus or accessory nerves are commonly described complications. Although the phrenic nerve courses within the surgical planes explored during a neck dissection and has a vital function in innervating the diaphragm, few studies have been performed to investigate the exact incidence of post-operative phrenic nerve paresis. This study aims to review the literature as to the rate of phrenic nerve injury following neck dissection.

A systematic literature review was conducted from 2000 to 2022 including studies reporting on phrenic nerve paresis following neck dissection.

In total, 11 studies were included. The reported rate of immediate post-operative phrenic nerve paresis ranged from 0% to 5.3%, with an average rate of 0.613% (12/1959). The reported rate of phrenic nerve paresis at follow-up (1 month-127 months) ranged from 0% to 4.7%, with an average rate of 1.035% (5/483). There were no cases of bilateral phrenic nerve paresis reported in this period.

Phrenic nerve paresis is an uncommon complication following neck dissection, often asymptomatic and potentially underreported. Bilateral phrenic nerve paresis is exceedingly rare. Injury can be avoided by staying superficial to the prevertebral fascia when dissecting around the anterior scalene muscle. Routine phrenic nerve integrity monitoring is not commonly utilized but may aid intra-operative phrenic nerve identification or confirmation of function.