Effect of the stapedotomy technique on early post-operative hearing results—Preliminary results

Abstract

Objective

To compare three stapedotomy modalities used to fenestrate the stapes footplate in patients with primary otosclerosis.

Materials

The non-randomized and unblinded one-center study included 48 patients with primary otosclerosis who underwent stapes surgery between May 2008 and April 2009. The patients were divided into three groups (single shot and two-shot CO₂ laser stapedotomy, perforator) depending on the modality used for stapedotomy. Bone conduction (BC) and air conduction (AC) thresholds, air–bone gap (ABG), and the difference between mean pre-operative and 2- to 3-week post-operative BC thresholds were analyzed.

Results

The temporary BC deterioration was most pronounced at 6 and 8 kHz after 2-shot laser stapedotomy. A significant drop in AC or BC was not found in any of our 48 patients. Age, high-dose cortisone therapy, and ‘preoperative hearing’ did not influence the post-operative hearing results.

Conclusion

Even though the number of patients presented here was small and statistical analysis was limited, the study showed a trend toward worse BC thresholds at 6 and 8 kHz after a second shot CO₂ application. Whenever possible, treatment should avoid a second laser shot on the already opened inner ear with the laser parameters used for the initial shot.

Introduction

One-shot CO₂ laser application is a widely accepted technique in stapedotomy. It is described as a safe procedure [1], [2], [3] used to create a perforation in the stapes footplate with a diameter of about 0.5–0.6 mm depending on the laser parameters used for laser application. The main advantage of a laser assisted stapedotomy over conventional stapes surgery (perforator) or stapedotomy techniques using a microdrill or piezoelectric devices [4] is to avoid a mechanical trauma of the inner ear. The laser assisted stapedotomy technique has been described as well suited for primary stapes surgery [2] and has also been recommended as a standard procedure in revision stapes surgery [5]. Several authors have reported good audiological results after CO₂ assisted laser stapedotomy and did not find a significant sensorineural hearing loss in the speech range [6].

High frequency sensorineural hearing losses (SNHL) following stapes surgery were described by Robinson and Kasden in 1977 [7]. Since then, several authors have reported a distinct sensorineural hearing loss after stapes surgery in the high frequency range from 2 to 8 kHz. The main factors were considered to be: aspiration of the perilymph during surgery, mechanical trauma during preparation, and bleeding into the vestibule. SNHL was also observed after laser stapedotomy [8]. Deterioration of bone conduction was found after potassium titanyl phosphate (KTP) and CO₂ laser stapedectomy, being 7.1 dB and 6.7 dB at 4 kHz 1 and 2 weeks post-operatively, respectively. At 8 kHz, a persistent drop in air conduction (AC) was reported. Neither the laser system used (KTP versus CO₂) nor the surgery status (primary versus revision surgery) showed significant differences in audiological results post-operatively. Recently, a retrospective chart study has revealed a deterioration in bone conduction (BC) of approximately 6 dB at 4 kHz and 8 dB at 8 kHz 4–6 weeks after stapes surgery [9]. The authors performed CO₂ laser assisted stapes surgery in 53 patients. The fenestration of the footplate was carried out with a CO₂ laser. Whenever possible, a partial stapedectomy was performed removing the central fragments and the posterior half of the footplate.

The specific aim of this study is to compare two stapedotomy techniques in the surgical treatment of otosclerosis. The early audiological data of patients who were treated with CO₂ laser stapedotomy (one shot versus repeated shots) were compared with those in whom the perforator was used. The effects of high-dose cortisone therapy, pre-operative hearing level, and patient age were also considered.