Radiologic Findings after Transpromontorial Approach: Clinical and Pathophysiological Considerations.

Objectives: Transpromontorial approaches require obliteration of the surgical cavity and the eustachian tube, along with cul-de-sac external auditory canal closure, without obliteration of the mastoid air cells. This study aims to evaluate the clinical and radiological implications of tympanic cavity obliteration when the mastoid air cell system is preserved.

Study Design: Retrospective observational study.

Setting: Tertiary referral center.

Patients: Thirty-one adult patients with unilateral vestibular schwannoma.

Intervention: Patients underwent resection of a vestibular schwannoma through either an exclusive endoscopic transcanal transpromontorial approach (endoTTA) or an expanded transcanal transpromontorial approach (expTTA).

Main Outcome Measure: Postoperative radiologic mastoid and surgical cavity content and clinical outcomes.

Results: Thirty-one patients met the inclusion criteria. The mean radiological follow-up was 54 months. Regarding mastoid content, air was present in 13 patients (42%) and trapped fluid in 18 patients (58%). Surgical cavity content revealed air in 14 patients (45%), trapped fluid in 8 patients (26%), total fat obliteration in 5 patients (16%), and partial fat obliteration in 4 patients (13%). No cases of mucocele, cholesterol granuloma, or iatrogenic cholesteatoma were observed. Three main radiological patterns were identified by combining mastoid and surgical cavity findings. EndoTTA was found to be significantly associated with postoperative radiological air content in the mastoid cavity (p value = 0.013), while no association was found between the type of radiological pattern and the development of complications or symptoms at the last follow-up.

Conclusions: EndoTTA and expTTA are safe and effective procedures, with no increased risk of meningitis or CSF leak, even in cases where obliteration tissue is reabsorbed.