Depth of stapes prosthesis in the vestibule: baseline values and correlation with stapedectomy outcome.

CONCLUSION: Deeper protrusion of the prosthesis into the vestibule does not correlate with worse postoperative hearing outcome. OBJECTIVES: To establish baseline values for the depth of the stapes prosthesis in the vestibule after stapedectomy and to investigate a possible correlation between the relative prosthesis depth (actual depth expressed as a percentage of the vestibule depth) and the hearing results. METHODS: This was a prospective case study. Sixteen patients underwent stapedectomy and were examined by high-resolution CT of the temporal bone during the first week after surgery. They then underwent audiometric follow-up at specified intervals during the first postoperative year. The actual depth of the prosthesis in the vestibule, its relative depth, and correlations between the relative depth and postoperative hearing results (at 1 week, 1 month, and 1 year) or postoperative complications (prolonged vertigo and sensorineural hearing loss) were measured. RESULTS: The actual depth of the prosthesis in the vestibule (mean +/- SD) was 2.39 +/- 0.42 mm (range 1.83-3.39 mm). The depth of the prosthesis relative to the depth of the vestibule was 52 +/- 9.74% (range 41.3-74.2%). In general, deeper protrusion of the prosthesis into the vestibule did not correlate with a worse hearing outcome. On the contrary, the correlation between prosthesis depth and better hearing results was positive at several frequencies.

Vibrant soundbridge surgery: evaluation of transcanal surgical approaches.

UNLABELLED: Since its introduction, surgery for the placement of the Vibrant Soundbridge (VSB) device has been performed using a facial recess approach. Because of the size of the VSB device, this approach requires a large facial recess that can lead to complications, i.e., facial palsy and/or taste disturbance. The purpose of this study is to develop and compare transcanal surgical approaches for leading the VSB into the middle ear. SETTING: Cadaver temporal bones in a university temporal bone laboratory. MATERIALS AND METHODS: First, two experienced senior surgeons validated the three possible approaches in human temporal bone: 1) the classical facial recess approach; 2) a small mastoidectomy, elevation of a tympanomeatal flap, small atticotomy, 0.5-mm cutting of the bony external auditory canal (EAC) from the cortical plane on its approximately two-thirds to three-fourths and then a trough to pass the electrode array into the middle ear; and 3) similar to the second approach but with replacing the cutting of the bony EAC with a tunnel from the mastoid cavity to the EAC. Both the second and third approaches were transcanal. Next, five residents and six attending surgeons performed the three operations and evaluate these different approaches by using analog visual scales (VAS) for each procedure. They assess the following: 1) the ease of passing the electrode array and the Floating Mass Transducer (FMT) into the middle ear, 2) the ease for FMT clipping, and 3) their self-confidence using each approach. Time required for the three operations was measured. Measurements of landmarks were obtained on all temporal bones. Two patient cases illustrate the clinical application of this new surgical approach. RESULTS: The two transcanal approaches were assessed to be easier, faster, and safer methods for VSB surgery than the classic facial recess approach. CONCLUSION: VSB surgery has been performed using a facial recess approach with risk for facial nerve and taste disturbance. Transcanal approaches are good alternative for this surgery. Three major limitations are to be assessed in future patient studies: the pathologic findings of the EAC, the design of the FMT regarding the axis of the ossicular chain, the long-term evaluation of the skin of the external ear canal.

Stapes surgery: the diameter of the long process of the incus.

HYPOTHESIS: The aim of this study was to examine the long process of the incus in respect of its shape and its dimensions at the site of the attachment of a stapes prosthesis. BACKGROUND: One of the complications in stapes surgery is the erosion of the long process of the incus at the site of the attachment of the prosthesis, resulting in a fluctuating conductive hearing loss. Knowing the dimensions of the attachment site of the prosthesis at the long process of the incus will make it possible to optimize the size of the prosthesis loop. METHODS: The incus was obtained from 11 patients who had undergone middle ear surgery for hearing improvement or cholesteatoma removal. The ossicles were kept in 4% paraformaldehyde and were processed for histological examination after decalcification in ethylenediamine tetra-acetic acid. The 5-microm slices were stained with toluidine blue and examined in the light microscope. Using digitized video images of the histological slices, the diameters, circumference, and surface of the specimens were determined. RESULTS: The diameter of the long process of the incus at 1.4+/-0.28 mm from the tip, which is the average site of prosthesis attachment, showed an oval shape with a minimum diameter of 0.66+/-0.05 mm, a maximum diameter of 0.81+/-0.1 mm, and a circumference of 2.46+/-0.23 mm. CONCLUSION: The loop of a stapes prosthesis should have the following dimensions: diameter 0.9 mm, loop length of 2.2 mm, and opening of loop 0.7 mm. However, the material of the prosthesis and its malleability are also important factors.

Long-term results of ossiculoplasty: reasons for surgical failure.

OBJECTIVES: To present the value of a dedicated ear audit clinic, the overall long-term results of ossiculoplasty, and the reasons for surgical failure. STUDY DESIGN: Retrospective analysis was performed on ossiculoplasty cases in a county hospital. The information was extracted from a computer database. Individual patient case records were reviewed in all cases of surgical failure. METHODS: All patients who had ossiculoplasty were routinely followed-up in a dedicated ear audit clinic on a yearly basis. Between 1988 and 1999, the author performed 242 ossiculoplasties and their outcomes were monitored in the ear audit clinic. The 5-year results are presented. RESULTS: Even with the benefit of a dedicated audit clinic and a stable population, only 74.4% of ears had a known outcome at 5 years after ossiculoplasty. In the present series, 61.1% of partial and 37.6% of total ossicular reconstructions have an air-bone gap of 20 dB or better at 5 years. Of 83 identifiable late failures, 47 were caused by persistent or recurrent abnormalities within the middle ear and only 36 were thought to be caused by prosthesis-related or surgeon-related problems. CONCLUSION: The overall long-term results of ossiculoplasty have not dramatically improved in recent years, in spite of all the great advances in biomedical technologies. Unless there is a breakthrough in the understanding and management of the underlying otitis media, the long-term outcome of ossiculoplasty is unlikely to improve dramatically.

Audiometric evaluation of an attempt to optimize the fixation of the transducer of a middle-ear implant to the ossicular chain with bone cement.

Typically, an implantable hearing device consists of a transducer that is coupled to the ossicular chain and electronics. The coupling is of major importance. The Vibrant Soundbridge (VSB) is such an implantable device; normally, the VSB transducer is fixed to the ossicular chain by means of a special clip that is crimped around the long process of the incus. In addition to crimping, bone cement was used to optimize the fixation in six patients. Long-term results were compared to those of five controls with crimp fixation alone. To assess the effect of bone cement (SerenoCem, Corinthian Medical Ltd, Nottingham, UK) on hearing thresholds, long-term post-surgery thresholds were compared to pre-surgery thresholds. Bone cement did not have any negative effect. Next, to test the hypothesis that aided thresholds might be better with the use of bone cement, aided thresholds were studied. After correction for the severity of hearing loss, only a small difference was found between the two groups at one frequency, viz. 2 kHz. It was concluded that there was no negative effect of using bone cement; however, there is also no reason to use bone cement in VSB users on a regular basis.

A comparison of the user-friendliness of hydroxyapatite and titanium ossicular prostheses.

Both hydroxyapatite (Ha) and titanium (Ti) are well-accepted alloplastic materials for ossicular prostheses. Many different designs of Ha and Ti prostheses are presently available. Fourteen surgeons of different seniority and surgical experience were asked to 'test-drive' four different types of ossicular prostheses in cadaveric temporal bones to investigate the user-friendliness of these protheses. The Goldenberg design Ha incus prosthesis and the Dusseldorf design Bell Ti prosthesis were used as partial ossicular replacement prostheses (PORP). The Richards design Ha incus-stapes prosthesis and the Dusseldorf design Aerial Ti prosthesis were used as a total ossicular replacement prostheses (TORP). Nine out of 14 surgeons found the Ha PORP to be more user-friendly because of the notch design in the head. The Ti prosthesis was found to be more difficult to manipulate because it was too light. Half of the surgeons preferred the Ti TORP because of the open design of the top-plate. The Ha TORP was thought to be too top-heavy and to have a tendency to fall over.