Bone Cap for Tegmen Tympani Reconstruction: Case Series with Surgical and Cadaver Pictorial Correlation

Objective: To describe technical nuances and clinical correlations of a lateral skull base reconstruction technique for tegmen tympani defects. Defects of the tegmen tympani can be problematic, particularly if they are associated with a cerebrospinal fluid (CSF) leak or ossicles exposure.

Study Design: Retrospective case review supplemented with intraoperative pictures and cadaver dissections.

Setting: Tertiary university hospital.

Methods: Adult patients from 2014 to 2016 who underwent surgical repair of a lateral skull base tegmen tympani defect using a bone cap technique to recreate the epitympanum.

Results: Six patients (seven ears) underwent a middle cranial fossa approach for repair of a tegmen tympani defect using a calvarial bone graft carved into a bone cap for reconstruction of a neo-epitympanum. Six ears underwent surgery for a CSF leak and one ear had surgery for resection of a Giant Cell Tumor. Mean age was 53.4 years (SD: 13.2) and mean follow-up was 1.0 year (SD: 0.8 year). The six patients with CSF leaks had a mean body mass index of 43.1 (SD: 7.1) and all had resolution of their CSF leak using this technique alone. The five patients with spontaneous CSF leaks improved their pure-tone average by 6.7 dB (SD: 4.4) and their air-bone gap by 7.5 dB (SD: 10.2) without any decline in speech discrimination. Preoperative and postoperative radiographs as well as intraoperative pictures highlight technical nuances of the surgical technique. Additional cadaver dissections were performed to reinforce the key surgical steps.

Conclusion: Tegmen tympani defects are commonly associated with CSF leaks, encephaloceles, and conductive hearing loss secondary to ossicular chain disruption. Recreating an epitympanic space using a free bone graft carved into a bone cap is a useful technique for stopping the leak and creating adequate space for ossicular movement.