Surgical Technique for Repair of Middle Fossa Cranial Fossa Semicircular Canal Dehiscence: A Retrospective Case Series Review

Objective: Tegmen tympani or tegmen mastoideum dehiscence refers to a defect in the bone of the lateral skull base usually overlying the middle ear and mastoid air cells. Tegmen dehiscence presentation ranges from hearing loss, aural fullness, otalgia, and cerebrospinal fluid (CSF) leak to more serious complications such as meningoencephalocele formation, meningitis, and intracranial abscesses. The risk of meningitis often necessitates surgical intervention with the goal of repairing the defect, resecting any meningoencephaloceles, and preventing further CSF egress. Multiple techniques for repair have been proposed, each with their respective benefits and limitations. In this study, we describe a middle fossa craniotomy technique utilizing a split thickness bone graft, pericranial pedicled flap, and hydroxyapatite for extradural repair and intradural repair with an inlay graft. Our aim is to assess the postoperative outcomes of this innovative method.

Methods: We retrospectively reviewed the clinical records of 20 patients who underwent tegmen dehiscence repair using this technique at our institution between December 2017 and July 2023. Inclusion criteria consisted of adult patients with tegmen dehiscence who underwent the technique described in our study. Exclusion criteria included patients undergoing the procedure for neoplastic or trauma indications or patients undergoing repair with a different technique. We recorded demographic characteristics, presenting symptoms, etiology, and preoperative findings. Postoperative outcomes were evaluated by assessing symptom resolution, need for reoperation, and development of new dehiscences.

Results: Our case series encompassed 24 tegmen dehiscence repairs in 20 patients, with an average age at surgery of 51.5 years (range: 24–80). The average follow-up time was 13.3 months (range: 1.7 weeks to 58.6 months). Patients commonly presented with symptoms such as hearing loss (n = 9), fullness or ear pressure (n = 9), dizziness or vertigo (n = 7), or a history of meningitis (n = 2), among others. Postoperatively, symptoms resolved completely in 35% of patients (n = 7) and partially in 65% of patients (n = 13). Notably, no patients required revision surgery or developed new dehiscences in the follow-up period.

Briefly, our technique involves harvesting a pericranial flap, followed by a standard middle fossa craniotomy that is high enough to maximize thick bone for the graft. The split calvarial bone graft is harvested from the inner cortical mantle of the bone flap. Under the microscope, the meningoencephaloceles are identified and excised, and the dural defects are incorporated into one dural opening. An Alloderm inlay is then placed, followed by primary dural closure. For extradural repair, the split calvarial bone graft is placed over the tegmen defect(s) and reinforced with hydroxyapatite, followed by an overlay with the pericranial flap ([Fig. 1]).

Conclusion: Our middle cranial fossa craniotomy technique for tegmen dehiscence repair demonstrated promising postoperative outcomes, with complete or partial symptom resolution in all patients and no major complications. Our findings suggest that this technique is a safe and effective approach for tegmen dehiscence repair. Further research with larger sample sizes is needed to validate these results and assess long-term outcomes.

Fig. 1

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Artikel online veröffentlicht:
05. Februar 2024