Ossicular Chain Trauma during Middle Ear Endoscopy

Abstract

Objectives:

(1) Evaluate the risk of ossicular chain trauma and injuries due to different middle ear endoscopic techniques and maneuvers. (2) Describe types, incidence, and causes of these injuries. (3) Suggest methods to avoid them.

Methods:

Thirty temporal bones were approached using 0°, 30°, and 70° otoendoscopes with 2.7 mm and 4 mm diameters. Three areas were systematically approached in each bone: retrotympanum, protympanum and epitympanum. They were also manipulated using 3 sets of otologic surgical instruments: regular straight, regular curved and especially designed for endoscopic ear surgery.

Results:

The most common injury was the fracture of the posterior stapedial curs (27%). Other types were incudostapedial joint dislocation (23%), fracture of foot plate (23%), stapes dislocation (17%), fracture both stapedial crura (13%), fracture of the incus long process (6%), and incudomalleolar joint dislocation (3%). Single injuries were 44% and combined or multiple injuries were 56%. Highest incidence of injuries was with the 70° otoendoscope (89%) and with both the straight and curved regular instruments (67%). The diameter of otoendoscopes did not affect the number of injuries. Positioning of the scopes and familiarity with the technique reduced the incidence of trauma.

Conclusions:

Middle ear endoscopy can lead to a significant risk of ossicular chain injuries with their sequelae on hearing. Minimizing this risk necessitates adequate familiarity with the anatomy, techniques and otoendoscopes and usage of especially designed surgical instruments. In addition, combining both microscopic and otoendoscopic approaches or surgically assisted otoendoscopic approaches can reduce this risk considerably.