Noise Levels Generated By Electrical Drills And Suctions During Neurotological Surgery And Effects Of Them On Hearing

Objective Sensorineural hearing loss(HL) that may follows tympanomastoid surgery is one of complication of middle ear surgery. The noise-induced hearing loss has been one of the most commonly discussed issues in recent years. To investigate noise levels related to drilling, suctions and factors affecting noise level during a cochleostomy procedure. To explore possible contribution of drill-generated noise during mastoid surgery to postoperative sensorineural HL is to provide theory for clinical therapy.Method Noise levels generated by various burrs in 12 fresh human temporal bones were measured using an ER-7C Sound Level Meter. The Max and Rms levels were analyzed. Twenty pations have been followed up to investigate what happens in nonoperated ear in prospective studies.Resul 1 The Max and Rms noise levels generated by cutting burrs ranged from 120.4 to 121.7 dB SPL and from 108.3 to 110.6 dB SPL respectively when drilling the mastoid cortex; 2 The Max and Rms noise levels produced by cutting and diamond burrs ranged from 116.8 to 121.5 dB SPL and from 105.4 to 110.1 dB SPL respectively when drilling inside the mastoid cavity. The noise levels generated by cutting and diamond burrs were not statistically different; 3 The Max and the Rms noise levels during cochleostomy ranged from 116.0 to 131.5 dB SPL and from 108.6 to 124.9 dB SPL, respectively. The highest SPLs during cochleostomy were recorded when a turning bur first touched the intact endosteal membrane, in excess of 130 dB SPL.4.The Max and Rms noise levels ranged from 99.9 to 128.7 dB SPL and from 84.8 to 117.2 dB SPL respectively. The noise level increased as the diameter of suction tips increased. The differences among tips of sizes greater than 2 millimeters were however not statistically significant. 5.The amplitudes of the bone-conduction thresholds of contralateral ear in seven pations(35.0%) were found increasingly two weeks or one months after surgery and progressive improvement was detected with full recovery three months after surgery, who came from twenty pations.Conclution: 1.Noise levels generated by electrical drills during neurotological surgeries can be very high, especially when the intact endosteal membrance comes into contact with the running burr, potentially capable of inducing sensorineural hearing loss. Shortening noise exposure is therefore an important step in improving surgical techniques in neurotological operations, to reduce noise induced hearing loss. 2.Suction-related noise levels during neurotological surgeries can be very high. Use of suction in such procedures should be minimized and suction tips kept away from the cochlea whenever possible to avoid inducing unnecessary inner ear damage by noise.3.The noise during otological surgery can cause temporary hearing threshold changes in the contralateral ears. This advers effect recovers in three months postoperatively.