Abstract
Exostoses are bony outgrowths of the external auditory canal (EAC) that can lead to cerumen entrapment, recurrent infections, and conductive hearing loss. When surgical removal is indicated, a drill or osteotome may be used via a post-auricular, endaural, or transcanal approach. Studies suggest that exostoses removed by transcanal osteotome result in decreased morbidity when compared to open, drilled approaches; however, inadvertent injury to the facial nerve or inner ear is a theoretical concern given the restrictive geometry of the EAC and challenges of visualizing the tip of the chisel through the microscope. The endoscope provides superior visualization of the external auditory canal and tympanic membrane compared to the microscope. We sought to demonstrate the efficacy and safety of endoscopic exostosis surgery with an osteotome. We find that the endoscope provides improved wide angled views without blind spots. There were no intraoperative complications. Endoscopic canaloplasty for exostoses may be readily applied.
1
Introduction
Exostoses of the external ear canal (EAC) are lamellar bony outgrowths that commonly occur as a reaction to cold-water exposure . Numerous studies have addressed the surgical management of exostoses and debated approaches (post-auricular versus transcanal) and operative instruments (drill versus osteotome) . While the use of a high speed drill allows for precise bone removal and is believed to decrease the risk of injury to surrounding structures, it may result in sensorineural hearing loss (SNHL) due to direct transmission of sound to the cochlea . The osteotome may avoid the risks of tinnitus and SNHL; however, studies have expressed concerns for the risk of injury to the facial nerve, tympanic membrane, and temporomandibular joint due to lack of landmarks and visualization .
Recently there has been increased application of endoscopes for otologic surgery as a ‘minimally invasive approach’ given that transcanal procedures avoid the need for a post-auricular incision. Advocates of endoscopic ear surgery espouse its high resolution, magnification, and wide-angle view. These features make the endoscope an ideal instrument for visualization of the EAC in osteotome-assisted exostosis removal, and address the safety concerns. Herein, we describe endoscopic transcanal resection of EAC exostoses.
2
Materials and methods
Institutional review board approval was obtained.
2.1
Representative operative technique
A healthy 88-year-old male had a history of left sided recurrent otitis externa and persistent aural fullness. Otologic exam revealed several large exostoses. Medial debris was difficult to remove and the tympanic membrane could not be visualized. He was taken to the operating room (OR) for removal of the exostoses where endoscopic and microscopic equipment was available. ( Fig. 1 ) Using a 3.0 mm, 14 cm, 0° endoscope, three large, occlusive exostoses were identified just lateral to the tympanic ring. ( Fig. 2 ).
The operation was performed under endoscopic surveillance. Lidocaine with epinephrine 1:100,000 was infiltrated at the bony-cartilaginous junction. A Rosen knife was used to incise the skin crest of the first exostosis to fully expose the extent of the bony lesion. A 2.0 mm straight osteotome was applied at the base. Using a “three-handed” technique ( Fig. 3 A ), the lesion fractured with gentle tapping at its base and completely mobilized. A cup forceps was used to remove the bony mass in one piece. This allowed for removal of the remaining medial debris and afforded a complete view of the tympanic membrane using the endoscope. The 2.0 mm osteotome was again used on the remaining exostoses with the annulus in view. ( Fig. 3 B and C). Epinephrine 1:1000 soaked cotton balls were used frequently to maintain hemostasis during the dissection.
The ear canal was irrigated with saline, suctioned, and then inspected using the endoscope. The tympanic annulus was intact, as the skin medial to the exostosis was not disrupted. Skin edges were then laid down with good coverage at the base of each exostosis. Gelfoam pieces were placed sequentially from the tympanic membrane out to the lateral canal. The patient was returned to the anesthesia team for postoperative care.
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