Styloglossus muscle: a critical landmark in head and neck oncology

To document the role of the styloglossus muscle (SG) in head and neck oncology and at the time of surgical treatment and mandibular preservation surgery for squamous cell carcinoma of the lateral oropharynx (SCCLO).

Based on a search conducted within the Pubmed, Embase, and Cochrane databases, using the key words SG muscle, parapharyngeal space and oropharynx, the authors discuss the embryology, physiology, anatomy and radiology of this muscle as well as its role in the oncologic staging surgery of SCCLO.

The most specific radiologic exam to evaluate the involvement of SG muscle in SCCLO is magnetic resonance imaging (MRI). According to the eigth international staging classification systems, radiologic invasion of the SG muscle, at the time of MRI, leads to reclassify as T4a many tumors considered as T1-3 at the time of clinical and/or on computerized tomography evaluation. This must lead to extreme care when comparing oncologic results from series published prior and after the MRI era. When transoral resection of the SG muscle is advocated for SCCLO, one must know that this maneuver brings numerous arterial and venous structures within the operative field. If difficulties to achieve safe margins of resection and/or to control bleeding are encountered, a simple trans cervical maneuver described herein is most useful.

The importance of the SG muscle should be emphasized as a touchstone for staging and surgeon's guide to mandibular preservation surgery of SCCLO. The various approaches allowing the control of this muscle and its vascular environment must be taught at the time of initial training.