Malleostapedotomy prosthesis size and shape: key measurements from a temporal bone study.

HYPOTHESIS: By determining the dimensions of middle ear anatomic relationships pertinent to malleostapedotomy (MS), a simplified, yet optimized scheme for sizing, shaping, and placing a prosthesis can be generated. METHODS: Surgical dissection of 20 fresh (nonpreserved) cadaveric temporal bones was undertaken. Needlepoint calipers were used to manually measure pertinent distances between the ossicles. These measurements were then used to calculate the dimensions of anatomic triangles within the middle ear that were applied to the process of MS prosthesis sizing, shaping, and placement. RESULTS: Mean distances were 6.3 mm (range, 5.75-7.0 mm) between the usual MS crimp site and stapedotomy site, 3.6 mm (range, 3.00-4.25 mm) between the crimp site and the lateral edge of the distal incus long process, 4.9 mm (range, 4.50-5.00) between the lateral edge of the distal incus long process and the stapedotomy site, 3.7 mm (range, 3.25-4.00) between the crimp site and the umbo, and 3.3 mm (range, 2.75-3.75) between the umbo and lateral edge of the distal incus long process. CONCLUSION: A total crimped prosthesis length of at least 7.75 mm is required to accommodate the range of interossicular measurements, yet production of longer prostheses is wise owing to the limited number of temporal bones studied. Furthermore, the use of a single-length prosthesis for all MS cases will not suffice except when cutting a sufficiently long prosthesis to its desired length. Understanding of the ossicular anatomy can be used to bend the MS piston to favorably affect the orientation of the prosthesis barrel into the vestibule.

Effect of epithelial stem cell transplantation on noise-induced hearing loss in adult mice.

Noise trauma in mammals can result in damage to multiple epithelial cochlear cell types, producing permanent hearing loss. Here we investigate whether epithelial stem cell transplantation can ameliorate noise-induced hearing loss in mice. Epithelial stem/progenitor cells isolated from adult mouse tongue displayed extensive proliferation in vitro as well as positive immunolabelling for the epithelial stem cell marker p63. To examine the functional effects of cochlear transplantation of these cells, mice were exposed to noise trauma and the cells were transplanted via a lateral wall cochleostomy 2 days post-trauma. Changes in auditory function were assessed by determining auditory brainstem response (ABR) threshold shifts 4 weeks after stem cell transplantation or sham surgery. Stem/progenitor cell transplantation resulted in a significantly reduced permanent ABR threshold shift for click stimuli compared to sham-injected mice, as corroborated using two distinct analyses. Cell fate analyses revealed stem/progenitor cell survival and integration into suprastrial regions of the spiral ligament. These results suggest that transplantation of adult epithelial stem/progenitor cells can attenuate the ototoxic effects of noise trauma in a mammalian model of noise-induced hearing loss.

Acquired cholesteatoma in children following congenital cholesteatoma surgery.

OBJECTIVES: To determine the incidence of severe atelectatic otitis media and acquired cholesteatoma (AC) in children treated for congenital cholesteatoma (CC). METHODS: Retrospective chart review of 15 children who underwent primary surgery for CC over a 15 year period by a single surgeon. RESULTS: The mean postoperative follow up was 3.1 years. Significant tympanic retraction occurred in 6 children, included a retraction pocket that required T-tube insertion (3), and AC requiring tympanomastoid surgery (3). There was no complication related to retraction pocket in 9 children however 2 developed residual disease. In comparing the two groups, those with and without subsequent significant tympanic retraction, both groups had similar gender, age, extent of CC (median Potsic grade of 2), bone erosion, and surgical technique. Differences were noted in air-bone gap at presentation (PTA 32.4 and 17.25), otitis media with effusion in the contralateral ear (3/6 and 1/9), smaller mastoid volume ratio compared with the contralateral ear (0.74 and 1.21), and longer average timing for second surgery (14.8 months and 8 months). CONCLUSIONS: Acquired middle ear disease, including cholesteatoma, can follow surgical removal of CC, and long term follow up of all patients is required. Factors at initial evaluation indicative of risk of AC include a significant air-bone gap, otitis media with effusion in the contralateral ear and a smaller mastoid cavity ratio. The use of composite grafts at the time of CC surgery should be considered. Additionally, our findings suggest that the mastoid volume plays a causative role in the development of AC.

Changes in audiometric thresholds before, during and after attacks of vertigo associated with Meniere's syndrome.

CONCLUSION: No significant changes in hearing thresholds were observed during vertigo attacks associated with Meniere's disease. OBJECTIVES: To determine if the hearing alters during the period of the attacks of vertigo in Meniere's disease. PATIENTS AND METHODS: The study group consisted of patients who had a clinical diagnosis of definite Meniere's syndrome according to the AAOOHNS criteria, a score on the Gibson scale of 7 or over and an enhanced negative summating potential on transtympanic electrocochleography. These patients were supplied with a programmable hearing aid and a portable programmer that allowed them to measure their own hearing in situ. They were asked to measure their audiometric thresholds daily and if possible during the attacks of vertigo. RESULTS: Six of the patients were able to measure their hearing during attacks of vertigo and their hearing thresholds obtained before, during and after the vertigo attacks were compared. Five of six subjects showed <10 dBHL change in the hearing levels at all tested audiometric frequencies before, during and after the attacks of vertigo. One subject had a probable change in threshold before the attack but not during the attack of vertigo.

Update on long-term results with auditory brainstem implants in NF2 patients.

This study reviews the long-term results of auditory brainstem implant (ABI) in neurofibromatosis type 2 (NF2) patients. Retrospective chart reviews of patients who received an ABI at the Melbourne Cochlear Implant Clinic since 1995. Ten patients with an average follow-up of five years were included. Three patients received the N22 ABI and seven received the N24. Two patients discontinued use of their devices. Users reported part-time use for approximately four to five hours per day, switching their implants off in noisy environments. Audiological analyses at one to seven years post-implantation indicate that N24 patients showed worse performance at one year post-implantation but they continued to improve and, in the long term, both N22 and N24 groups achieved similar results. In conclusion, ABI provides a safe and useful tool for aural rehabilitation in NF2 patients. This study confirms that gradual improvement in performance occurs beyond one year post-implantation, as speech perception scores continued to improve.