Modification and comparison of minimally invasive cochleostomy techniques: A pilot study

Objectives/Hypothesis: Bimodal stimulation may offer improved auditory function following cochlear implantation. Modification of technique during cochleostomy may minimize trauma and maximize residual hearing. We hypothesize that CO ₂ laser use during cochleostomy is useful and may decrease intracochlear trauma. This study examines the utility of CO ₂ laser to perform cochleostomy and compares intracochlear sound and temperature levels during laser and drill usage. Study Design: Experimental (30 cadaveric temporal bones). Methods: A CO ₂ laser at 3 W (four bones) and 6 W (four bones) and otologic drill (six bones) were utilized to perform a cochleostomy while recording operative time. Subsequently, 16 bones were used to simultaneously record intracochlear sound (in decibels) and temperature (in degrees Fahrenheit) during CO ₂ laser (eight bones) and drill cochleostomies (eight bones). Results: Average cochleostomy time for CO ₂ laser was 15.5 minutes (3 W) and 7.75 minutes (6 W); it was 8 minutes for the drill. Average intracochlear sound level was 54.9 dB during laser use and 89.9 dB during drill use (P <.001), whereas maximal levels were 75 to 118 dB during laser use and 95 to 136 dB during drill use (P =.018). Average temperature was 63.4°F during laser use and 61.5°F during drill use (P =.151), whereas maximum temperatures ranged from 66 to 120°F during laser use and 62 to 70°F during drill use (P =.045). Conclusions: CO ₂ laser can create cochleostomies comparable in operative time and intracochlear temperature to drilling while decreasing intracochlear sound levels. Further investigation is warranted to minimize trauma and maximize auditory function during cochleostomy.