The effect of angulation of the vibrating floating mass transducer on stapes velocity.

HYPOTHESIS: Changes to the angular position of the vibrating floating mass transducer (FMT) coupled to the long process of the incus will not affect stapes velocity. OBJECTIVE: The MED-EL Vibrant Soundbridge is an active middle ear implantable device, which constitutes an effective alternative to acoustic hearing aids for the rehabilitation of patients with sensorineural and mixed hearing loss. Because of varied anatomy, it is not always possible to position the FMT in line with the vibrating axis of the stapes. Changes in stapes velocity after angulation of the FMT are measured using laser Doppler vibrometry (LDV). METHODS: The study was performed on 7 human cadaveric temporal bones. The FMT was attached to the incus and angled at the recommended 0 degree or at 45 degrees relative to the vibrating axis of the stapes, and the stapes velocity measured using LDV. RESULTS: In comparison to the 0-degree position, angulating the FMT to 45 degrees reduced cochlea input as measured by stapes velocity, although there was no statistical significance to this difference. Placing the FMT at 45 degrees did not compromise the peak output of the device but resulted in a phase lag which was more marked compared with the 0-degree position. CONCLUSION: If it is not anatomically possible to position the FMT in line with the vibrating axis of the stapes, then placement at up to 45 degrees does not significantly alter the performance of the implant particularly in the midfrequencies that are crucial to the understanding of speech.

The atretic plate--a conduit for drill vibration to the inner ear?

CONCLUSION: In the presence of simulated congenital aural atresia with fixation of the ossicular chain to the surrounding bone, access to the chain for placement of a middle ear prosthesis using the rotating burr is not associated with significant stapes movement that would cause vibrational trauma to the cochlea. OBJECTIVES: To determine the energy transmitted to the cochlea while drilling the mastoid in an ear with simulated congenital aural atresia and fixation of the ossicular chain to the surrounding bone. METHODS: Eight human cadaveric temporal bones were used. Cement was placed in the external auditory canal and on the incudomalleolar joint and surrounding epitympanum, to simulate congenital aural atresia and ossicular fixation, respectively. Stapes vibration was measured with the Laser Doppler Vibrometer using acoustic then drill stimulation by touching the wall of the epitympanum with a running burr. RESULTS: Using acoustic stimulation, all bones showed frequency-specific reduction of stapes motion of up to 17 dB with fixation of the ossicular chain to the surrounding bone. There was no measurable stapes motion when the external auditory canal was filled with cement. On drill stimulation, there was no difference in stapes velocity between the normal bone and the bone with simulated congenital aural atresia.

Systematic review of cochlear implantation in children with developmental disability.

OBJECTIVE: To perform a systematic review comparing the xoutcome of cochlear implantation in children with developmental disability with children without developmental disability. DATA SOURCES: MEDLINE, EMBASE, and Cochrane databases were searched from 1950 or the start date of each database. The search was performed on 1st November 2012, and included articles published ahead of print with no language restrictions. STUDY SELECTION: The initial search presented 441 articles of which 13 met the inclusion criteria. The articles studied children with cochlear implants and developmental disability where expressive and/or receptive language outcomes were compared with children with cochlear implants and normal development. DATA EXTRACTION: Study quality assessment included whether ethical approval was gained, prospective design, eligibility criteria specified, appropriate controls used, adequate follow-up achieved, and defined outcome measures. Cochlear implant outcome analysis included expressive/receptive speech and language development in addition to quality of life and behavior. DATA SYNTHESIS: Because of heterogeneity in postoperative follow-up periods and outcome measures reported, it was not possible to pool the data and perform meta-analysis. Comparisons were made by structured review. CONCLUSION: Seven studies demonstrated a worse outcome for children with developmental disability. Six articles showed no difference in the outcome between the 2 groups. Children with developmental disability may not benefit from cochlear implantation based on traditional assessment tools but appear to improve their environmental awareness and quality of life. More work is needed to define the term benefit when used in this context for this vulnerable group. Autistic children consistently had a negative outcome.

De novo development and progression of endolymphatic sac tumour in von hippel-lindau disease: an observational study and literature review.

Endolymphatic sac tumors (ELST) are rare invasive lesions of the temporal bone that are commonly associated with von Hippel-Lindau disease. This report describes serial magnetic resonance imaging (MRI) and computed tomography (CT) findings over a period of 6 years in a 12-year-old patient who developed an ELST after 3.5 years surveillance for a cerebellar hemangioblastoma. A 1.5 × 8 mm tumor was identified on MRI within the endolymphatic duct when the patient presented with audiovestibular symptoms due to intralabyrinthine hemorrhage. The tumor demonstrated subsequent growth over 25 months until the patient agreed to undergo surgical resection by subtotal petrosectomy. De novo development and the natural history have been described only in six previous cases. MRI is regarded to be unreliable with respect to the ability to demonstrate an ELST in the presence of intralabyrinthine hemorrhage, with only two out of four previously reported patients demonstrating positive MRI findings. Little is known about the precise origin (endolymphatic duct versus sac), growth, and symptom correlation. This case highlights that new audiovestibular symptoms are a potential clinical clue and intralabyrinthine hemorrhage is a neuroimaging indicator for the presence of an ELST, which based on high-resolution MRI appears to originate in the endolymphatic duct rather than sac.