The main aim of this study was to evaluate 6-month closure success in surgery for isolated or non-isolated temporal bone osteomeningeal breach (OMB). Secondary objectives were to analyze complications of closure and correlations between success and breach, treatment and patient data.

This was a single-center retrospective observational study of patients who underwent surgery for temporal bone OMB via a middle cranial fossa or transmastoid approach in a French university teaching hospital between 2007 and 2022, with follow-up of at least 6months. Patients with superior semicircular canal dehiscence were excluded. Study data comprised gender, age, body mass index, OMB etiology, mode of discovery, audiometric and radiological data, surgical technique, length of hospital stay and postoperative complications. The primary endpoint was absence of a cerebrospinal fluid leak on MRI at 6months. Fisher's exact test or Chi² test were used for qualitative data and Student t-test for quantitative data.

The closure success rate was 87%: 81% (3 recurrences) in the middle cranial fossa group of 16 patients and 93% in the transmastoid group of 14 patients. Postoperative audiometry showed significant improvement (P=0.0016) for air conduction in the middle cranial fossa group. Five patients (17%) operated on via the middle cranial fossa approach and 1 (7%) operated on via the transmastoid approach had postoperative complications. OMB was in the tegmen mastoideum in 8 patients (29%), tegmen tympani in 7 (25%), tegmen antri in 4 (14%), tegmina antri and tympani in 3 (11%), antri and mastoideum in 1 (8%) and in the whole tegmen in 5 (18%). Eleven OMBs were lateral to the superior semicircular canal, 13 medial and 4 on either side.

The transmastoid approach is indicated in case of associated middle-ear procedures, patients aged over 75years or OMB lateral to the superior semicircular canal. The middle cranial fossa approach is reserved for OMB located medial to the superior semicircular canal patients under 75years of age without associated ossicular procedures. For patients with OMB medial to the superior semicircular canal who require middle-ear surgery, a combined approach can be used.