TREATMENT OF SEVERE OTOSCLEROSIS: COCHLEAR IMPLANTATION, STAPEDOTOMY, AND OTHER OPTIONS
Introduction
Severe otosclerosis is relatively rare in Japan compared with Western countries. In European hospitals, otosclerosis was listed as the cause of deafness in about 7% of all patients who received cochlear implantation.1 In Japan, otosclerosis was the only cause of deafness in only 1% of such patients according to Cochlear Company data. Although we only have a small number of cases with severe otosclerosis, we discuss the decision-making process with regard to severe otosclerosis based upon the findings in our cases and the literature.
Report of cases
Case 1
Case 1 is a 62-year-old female. Her hearing threshold was 120 dB in the right ear and 97.5 dB in the left ear (Fig. 1). In her past hearing records, we recognized bone conduction in the low frequency area. CT imaging of the petrous bone showed solely fenestral involvement (Fig. 2). It was classified as a so-called type 1 according to Rotteveel et al.1 Stapedotomy was performed on both ears in 2004 and 2005.
Fig. 1. Pre-operative audiogram of case 1.
Fig. 2. Pre-operative CT findings (both side ears) of case 1.
Eight years after the first operation, the hearing threshold was 90dB in the right ear and 86.3 dB in the left ear. With hearing aids on both ears, maximum speech discrimination score (SD) was 75%. CT imaging of the petrous bone showed solely fenestral involvement which was the same as before the operation. She was satisfied with her hearing now.
Case 2
Case 2 is a 51-year-old male. His hearing threshold was 107.5 dB in the right ear and scale out in the left ear (Fig. 3). In his past hearing records, we did not observe an air-bone gap. CT imaging of the petrous bone showed diffuse confluent retrofenestral involvement (Fig. 4). It was classified as a so-called type 3 according to Rotteveel et al.1 Cochlear implantation (CI) was performed on the right ear in 2007.
Fig. 3. Pre-operative audiogram of case 2.
Although his surgery was rather difficult because of bleeding and narrow scala tympani, the Cochlear Company device was inserted perfectly. Post-operatively, all electrodes could be used and the rehabilitation course was good. His maximum SD was 90%. He was called ‘a star patient’ by the president of the Cochlear Company.
Fig. 4. Pre-operative CT finding (right ear) of case 2.
Case 3
Case 3 is a 59-year-old male. His hearing threshold was 105 dB in the right ear and 100 dB in the left ear. CT imaging of the petrous bone showed a double-ring effect (so-called type 2A according to Rotteveel et al.1). With a hearing aid on the left ear, his maximum SD was only 15%. Now we are planning a CI for him.
Discussion
In Japan, there are three treatment options for patients with severe otosclerosis.
•Continuing hearing aids;
•Stapedotomy and hearing aid use;
•CI.
Stapedotomy is a relatively simple and inexpensive procedure. However, the results are unpredictable because measurement of bone conduction is often difficult and because an air-bone gap can occur without stapes fixation. When surgery and rehabilitation have been successful, CI has provided excellent results. However, it is an expensive and complex procedure. Surgery is often difficult in patients with progressive cochlear otosclerosis because of the difficulty in achieving full and exact insertion into the perilymphatic space. Furthermore, rehabilitation of such patients is challenging because progressive otosclerotic changes in the cochlea can affect performance of the implant in aspects such as facial nerve stimulation.
If the lesions of the patients with otosclerosis are not progressive and adequate hearing gain is likely to be acquired, then stapedotomy will be recommended. If adequate hearing gain is not likely, then CI will be necessary. CT imaging is expected to be an indicator of the progression of otosclerosis, because the hearing ability is likely to deteriorate when extensive lesions are present in CT imaging. In patients with severe otosclerosis, measurement of bone conduction is sometimes difficult. In such cases, SD with a hearing aid may be helpful. If maximum SD with a hearing aid is poor, then stapedotomy will not be effective. In our hospital, the average maximum SD after CI in all adult patients was 54%; a result that should be considered when planning for CI. From these ideas, we think that CT imaging, air-bone gap and SD may become important indicators for decision making in cases of severe otosclerosis.
Recently, Mercus et al.2 proposed the following algorithm guidelines based on SD, CT imaging and air-bone gap from their experience and the literature review. If maximum SD is under 30 dB, then CI should be considered. If maximum SD is between 30 dB and 50 dB and CT imaging shows type 2C or 3, then CI should be considered. If CT imaging does not show the findings, and air-bone gap is over 30 dB, then stapedotomy should be considered. If not, CT should be considered. If maximum SD is between 50 dB and 70 dB, and CT imaging shows type 2C or 3, then CI should be considered. If CT imaging does not show the findings, and air-bone gap is over 30 dB, then stapedotomy should be considered. If not, only hearing aid use will be considered. However, measurement of air-bone gap is sometimes difficult in patients with far-advanced otosclerosis because there are many scale-out cases in bone conduction. In such cases, past pure-tone average records will be helpful in addition to SD.
Conclusion
Therapy for severe otosclerosis should be considered with the use of CT imaging and air-bone gap values if the measurement of bone conduction is possible. Past pure-tone average records are also helpful, as is maximum speech discrimination with hearing aids before operation.
References
1.Rotteveel LJ, Proops DW, Ramsden RT, Saeed SR, van Olphen AF, Mylanus EA. Cochlear implantation in 53 patients with otosclerosis: demographics, computed tomographic scanning, surgery, and complications. Otol Neurotol 25:943–952, 2004
2.Merkus P, van Loon MC, Smit CF, Smits C, de Cock AFC, Hensen EF. Decision making in advanced otosclerosis: An evidence-based strategy. Laryngoscope 121:1935–1941, 2011
Address for correspondence: Hiromi Ueda, uehiromi@aichi-med-u.ac.jp
Cholesteatoma and Ear Surgery – An Update, pp. 115–118
Edited by Haruo Takahashi
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