STAPES SURGERY AND COCHLEAR IMPLANT SURGERY FOR SEVERE ORTOSCLEROSIS
Introduction
Profound deafness has received increasing attention, because of the availability of cochlear implants (CI). Consequently, it is especially important to remember that a ‘blank’ audiogram does not necessarily mean absence of hearing. Severe otosclerosis (far-advanced otosclerosis; FAO) generally involves air conduction (AC) levels worse than 85 dB, and bone conduction (BC) levels beyond the limits of the audiometer.1–4 If AC levels exceed 85 dB but BC levels are measurable at some frequencies but worse than 30 dB, the condition is called advanced otosclerosis (AO). Failure to recognize FAO or AO may result in unnecessary CI surgery.
Materials and methods
A retrospective analysis was conducted of the clinical charts of all patients who received stapes surgery (n = 306) and CI surgery (n = 536) at Osaka and Kinki University Hospitals from 1992 to 2012. Stapes surgery involved 210 ears in females and 96 ears in males. Otosclerosis accounted for 80% of the the stapes surgery. Objective improvement was noted in pure-tone audiogram (PTA), and subjective patients’ satisfaction with amplification was the real measure of success because the stapes surgery was performed to restore a serviceable hearing with Hearing aid (HA) for these FAO and AO patients.
Results
Among 306 stapes surgery cases, one patient (NS, 45 years old, male) with FAO received stapedotomy on the right ear, and another patient (MS, 56 years old, male) with AO received bilateral stapedotomy. Both patients had a positive family history of progressive hearing loss. MS’s daughter (KM, 28 years old) received partial stapedectomy on the left ear, and the result was excellent. AC levels were worse than 85 dB bilaterally in both patient, and BC levels were not measurable at most (not all) frequencies. The past audiograms and the family history help us to diagnose FAO and AO. Pre-operatively, both patients (NS and MA) were not successful hearing aid (HA) users, although both continued to use a HA anyway. Post-operatively, MS does not need HA any longer, while NS is still wearing HA unsuccessfully and considering CI surgery the left ear.
Among 536 CI surgery cases, just one patient (UH, 52 years old, male) had been found to have the history of otosclerosis preoperatively, and has been a good CI user postoperatively (Fig. 1A). HRCT demonstrated a massive sclerotic lesion bilaterally, indicating the presence of cochlear otosclerosis (Fig. 2A). Past audiograms clearly suggest the presence of an air-bone gap and a progressive nature of HL (Fig. 2B). After cochleostomy onto the promontory, the scala tympani was found to be filled with soft connective tissues. A full insertion of CI24RCS electrodes into the scala vestibuli was successfully completed. Among 2558 CI surgery cases, bilateral otosclerosis accounted for just 1% of the causes of deafness in Japan (Fig. 1B), according to a survey by the Cochlear Corporation in 2006.
Fig. 1. Profound hearing loss caused by otosclerosis. A: a case of the CI surgery with FAO; B: the causes of deafness in Japanese CI cases (2006).
Fig. 2. HRCT and PTA of a patient with FAO who received CI surgery. A: massive sclerotic lesions within bilateral cochlea; B: past audiograms suggesting a progressive hearing loss.
Discussion
A convincing histological explanation for increased bone-conduction threshold in FAO remains an issue for continued investigation. There are two types of otosclerosis described: a conductive disturbance limited to specific areas of the oval and round windows, and a more aggressive form called ‘cochlear otosclerosis’ with multiple foci developed relatively early in life. No correlation between BC thresholds and size of the lesion, activity of the lesion, involvement of endosteum or presence of a round window lesion in otosclerosis was found, while moderate diffuse loss of hair cells and cochlear neurons in the basal turn, and strial atrophy near the foci of otosclerosis were reported in FAO patients.
Sheehy2 published specific diagnostic clues for FAO: 1) positive family history for otosclerosis; 2) progressive hearing loss beginning in early adult life; 3) paracusis during the early stage of the disease; 4) past use of bone-conduction hearing aid; 5) previous audiograms showing an air-bone gap. In addition, the following criteria can be obtained from the physical examination: 1) normal voice; 2) positive Schwarze’s sign; 3) evidence of otosclerosis on HRCT; 4) a Weber test lateralizing to the poor ear or a negative Rinne test by a 512-Hz tuning fork; 5) no other apparent cause for hearing impairment. The diagnosis is just presumptive and can be confirmed only at surgery. All of our cases showed a positive family history of hearing loss, a progressive hearing loss on the past audiograms, and sclerotic findings of cochlea on HRCT.
Patients with FAO may appear to be suffering from profound sensorineural hearing loss and are frequently directed to CI programs. Specific clues shown above can lead the clinician to suspect FAO, and some FAO patients who had been unable to use a hearing aid (HA) preoperatively obtained serviceable hearing with a
The most gratifying aspect of the stapes surgery for severe otosclerosis (FAO and AO) should be converting the patients’ hearing from non-serviceable to serviceable with HA. The patients must be aware not only of the risks of the procedure, but also of the relatively limited goals. On the basis of the conventional criteria for stapedectomy surgery, objective results would be sometimes disappointing in FAO. However, some FAO patients clearly do benefit from the surgery and show marked improvement in HA performance. The success rate was reported to range within 70–100%.1–4 If a successful outcome is not achieved, the patient might be suitable for the CI surgery.
References
1.House HP, Sheehy JL. Stapes surgery; selection of the patient. Ann Otol Rhinol Laryngol 70:1062–1068, 1961
2.Sheehy JL. Surgical correction of far-advanced otosclerosis. Otolaryngol Clin North Am 11:121–123, 1978
3.Glasscock III ME, Storper IS, et al. Stapedectomy in profound cochlear loss. Laryngoscope 106:831–833, 1996
4.Frattali M, Sataloff RT. Far-advanced otosclerosis. Ann Otol Rhinol Laryngol 102:433–437, 1993
Address for correspondence: Katsumi Doi, MD/PhD, 377–2, Oono-Higashi, Osaka-Sayama, 589–8511, Osaka, Japan. kdoi@med.kindai.ac.jp
Cholesteatoma and Ear Surgery – An Update, pp. 111–113
Edited by Haruo Takahashi
2013 © Kugler Publications, Amsterdam, The Netherlands