Intraoperative relationship between the retromandibular vein and the marginal mandibular branch of the facial nerve: a prospective surgical study and literature review.

PURPOSE: To prospectively evaluate the intraoperative relationship between the retromandibular vein (RMV) and the marginal mandibular branch (MMB) or inferior facial nerve division during parotidectomy, and to synthesize the relevant anatomical and surgical literature.

METHODS

Consecutive parotidectomy procedures performed over a one-year period were prospectively evaluated. The RMV-MMB/inferior facial nerve relationship was recorded intraoperatively, and variants were photographed and documented. A structured narrative literature review was performed to identify cadaveric, fetal, radiological, surgical series, and case reports describing RMV-facial nerve relationships. During this period, 44 parotidectomies were performed; the final anatomical analysis included the 35 cases in which the RMV-MMB/inferior facial nerve relationship could be clearly defined.

RESULTS

Thirty-five parotidectomy procedures were evaluated. The classical configuration, defined as the RMV deep/medial to the MMB or inferior facial nerve division, was observed in 27 cases (77.1%). Eight variants (22.9%) were documented: four cases (11.4%) showed MMB interposition between the superficial temporal vein and maxillary vein, and four cases (11.4%) showed a cervicofacial branch coursing deep/medial to the RMV. Across the literature review and the present cohort, 1454 sides/cases were summarized, including 1346 classical configurations (92.6%) and 108 variants (7.4%). Among these 35 cases, facial nerve dissection was performed anterogradely in 33 cases and retrogradely in 2 cases; both retrograde cases showed the classical relationship.

CONCLUSION

The RMV is a useful landmark during parotidectomy, especially in retrograde dissection, but its relationship with the MMB and inferior facial nerve division is not constant. Awareness of interposition and deep/medial nerve variants may help reduce the risk of venous bleeding, surgical-plane misidentification, and facial nerve injury.