Evaluation of endoscopic-assisted feline lateral bulla osteotomy: a cadaveric study.

Objectives: The aims of the study were to investigate if feline middle ear anatomy can be visualized using endoscopy via a lateral bulla approach and to determine if scope-assistance increases rates of successful entry into the hypotympanum during feline total ear canal ablation and lateral bulla osteotomy (TECA-LBO).

Methods: A total of 13 feline cadaver heads underwent CT to confirm the absence of pre-existing middle ear disease. For each head, an electronic coin toss was used to determine which ear would undergo endoscope-assisted TECA-LBO; a traditional TECA-LBO without the use of the scope was performed on the contralateral side. In endoscope-assisted procedures, a 1.9 mm scope was intermittently inserted into the tympanic bulla via a lateral bulla approach and used to identify middle ear structures, visualize the bony septum and confirm entry into the hypotympanum. After the bilateral TECA-LBO, the cadaver heads were imaged again and assessed for evidence of entry through the septum.

Results: Soft tissue and osseus structures of the middle ear were readily visualized with a 1.9 mm scope. Success rates for entry into the hypotympanum were high between both endoscope-assisted and traditional procedures, with entry confirmed for 12/13 ears in each group.

Conclusions and relevance: Endoscope assistance can facilitate the identification and examination of middle ear structures but does not appear to increase the success rate of entry into the hypotympanum during feline TECA-LBO, as entry through the bony septum was consistently accomplished even without scope-assisted visualization. Alternative benefits to scope assistance may exist, and future studies to elucidate its impact on rates of intraoperative trauma to middle ear structures are indicated.