Surgical Implication of the Supralabyrinthine Aircell Tract in Combined Petrosal Approach

Purpose: The aim is to safely perform the combined petrosal approach, a comprehensive understanding of the anatomy of the petrous pneumatization is required. The purpose of this study is to clarify the supralabyrinthine air cell tract and its surgical implication in combined petrosal approach.

Methods: From 2010 to 2019, we analyzed total 45 patients who underwent a combined petrosal approach for the petroclival meningioma removal. Medical records including operative findings and imaging studies were reviewed. We performed the 3D volumetric analysis of the supralabyrinthine air cell tract and analyzed the relationship between surgical corridor and exposed area of the lesion.

Results: Mean volume of supralabyrinthine air cell tract was 0.331 mm³ (SD = 0.542, range = 1.91) from internal acoustic canal to posterior semicircular canal. In cases with small supralabyrinthine air cell tract, we had to perform the additional petrosectomy including transcrusal petrosectomy, translabyrinthine petrosectomy, exposure of the jugular bulb, or exposure of the retrosigmoid space more widely. Large supralabyrinthine aircell tracts required less retraction of the sigmoid sinus. We found preoperative consideration of supralabyrinthine aircell tract, as well as lesion location, size, patient’s hearing condition and neurological abnormalities, was an important factor in the successful treatment of petroclival meningioma.

Conclusion: Before performing the combined petrosal approach, analysis of the supralabyrinthine aircell tract can help in more accurate surgical planning.