Minimally invasive anterior approach to upper cervical spine : Surgical technique

Objective: The transoral approach of Spetzler is the classic anterior access to the upper cervical spine that provides direct exposure for anterior decompression of the spinal cord. The risks of infection, the limits in extension, and the postoperative recovery difficulties of transmucosal access suggest the use of an alternative anterior extraoral approach in upper cervical surgery. However, this approach results in complications from nerve palsy because of excessive retraction of the hypoglossal and the superior laryngeal nerves. The goal of this work was to provide anatomic data for an anterior retropharyngeal upper cervical approach through a minimally invasive window below the hypoglossal and the superior laryngeal nerves. Methods: In two adult cadaveric cervical spines, the anterior approach using the Metrx tubular retractor system through a window between the hypoglossal nerve and the superior laryngeal nerve, as well as below these two nerves, is compared in the exposure of C1 and C2 anteriorly with the aid of an operating microscope. Results: A maximum diameter of the internervous window for the tubular retractor is reached beyond which the superior laryngeal nerve will be excessively stretched. Conversely, the tubular retractor can retract the superior laryngeal nerve superiorly without undue tension. Better proximal exposure is also made possible by angling an end-beveled tubular retractor on the mandible without undue compression on the hypoglossal and superior laryngeal nerves, the marginal mandibular branch of the facial nerve, and the submandibular gland. Conclusion: This minimally invasive approach can replace transoral surgery, allowing direct anterior access to Cl and C2 while allowing extension to the lower cervical spine.