Impact of floating mass transducer coupling and positioning in round window vibroplasty.

OBJECTIVE: The round window application of the Vibrant Sound bridge, the so-called round window vibroplasty, is gaining increasing popularity for hearing rehabilitation of patients with mixed hearing loss or conductive hearing loss. In these patients, conventional hearing amplification and/or surgical restoration is either not possible or has failed because of chronic ear disease, extensive otosclerosis, or malformations. The exact mechanisms of direct cochlear stimulation via the round window membrane are not yet completely understood. It is unclear what kind and what degree of contact is required between the floating mass transducer (FMT) and the round window membrane (RWM) to elicit a functional hearing perception with the implant. We investigated the coupling efficiency between the FMT and the RWM and how the efficiency is altered by the FMT position, the degree of FMT-RWM contact, and the use of a soft tissue coupler. STUDY DESIGN: Prospective cohort study. SETTING: Tertiary referral center in Western Australia. PATIENTS: Patients undergoing round window vibroplasty for a mixed or conductive hearing loss otherwise not aidable. INTERVENTION: Patients underwent round window vibroplasty and received audiological and coupling analysis in the follow-up. These data were then correlated with FMT positioning and the extent of FMT-RWM interface as determined by postoperative high-resolution temporal bone computed tomography. MAIN OUTCOME MEASURES: Coupling and hearing levels in relation to FMT positioning and degree of FMT-RWM contact. RESULTS: Of 10 patients, 8 were available for vibroplasty behavioral threshold testing. In 2 patients, testing could not be done because of wound breakdown requiring device explantation in 1 case, and in the other case, the bone conduction thresholds dropped 2 months after implantation, thus falling out of the performance range of the device. Postoperative FMT migration occurred in 50% of the patients (3/6) with recurrent chronic ear disease and status after multiple previous ear operations. All patients, including the 3 patients requiring surgical repositioning of the FMT, attained significantly improved speech in quiet and speech in noise when compared with the preoperatively best aided performance. All patients showed significantly improved average Abbreviated Profile of Hearing Benefit scores with the use of the FMT. Direct (partial or complete) contact with the RWM resulted in good coupling efficiency; soft tissue coupling resulted in a reduced coupling efficiency.

Cochlear implants in forty-eight children with cochlear and/or vestibular abnormality.

CT and MRI scans for 48 children with cochlear and/or vestibular abnormality were classified in decreasing severity; common cavity, Mondini plus enlarged vestibular aqueduct, Mondini dysplasia alone and enlarged vestibular aqueduct alone. No significant relationship between degree of cochlea abnormality and surgical issues (cerebrospinal fluid gusher, depth of insertion, number of electrodes) or speech perception/language outcomes was found. A significant relationship was observed between cerebrospinal fluid gusher and partial electrode insertion, fewer active electrodes and poorer sentence understanding. Optimum language outcomes were associated with younger age at implant.

Preliminary outcomes of cholesteatoma screening in children using non-echo-planar diffusion-weighted magnetic resonance imaging.

OBJECTIVE: Diffusion-weighted (DW) MRI imaging is evolving into an alternative to second look surgery in detection of cholesteatoma recurrence. Insights into the DW MRI appearances of postoperative or inflammatory mucosal changes have recently described using non-echo-planar, turbo spin-echo (TSE) DW MRI which reliably distinguishes between postoperative changes and cholesteatoma. We investigated the use of TSE DW MRI in our pediatric population in order to validate a rapid and cost-effective MRI sequence that can be used to screen for cholesteatoma. METHODS: Prospective comparative study with adult and pediatric patients at a tertiary referral centre. Patients in the study underwent TSE DW MRI prior to second look or revision surgery for cholesteatoma. A Siemens 1.5 T scanner was employed, using the HASTE sequence (EPI DW MRI) as well as standard echo-planar DWI, T1 and T2 sequences. The MRI findings were then correlated with the intraoperative findings at surgery 9-15 months after primary surgery, or of revision surgery in the cases that were referred from other centres. Detection and localisation of cholesteatoma on TSE DW MRI were compared with the findings at second surgery, long considered the gold standard for detection of residual or recurrent disease. Scanning time between the TSE sequence and the standard planar DW MR were also compared. RESULTS: In a cohort of 92 patients, 21 pediatric patients were identified. 15 patients have had their 15 second look or revision procedures and DW MRI prior to their surgery. TSE DW MRI detected cholesteatoma and reliably identified the location of the cholesteatoma in 2 patients whom all had disease confirmed at surgery. The 13 cases with negative preoperative DW MRI for cholesteatoma were all confirmed to be disease free at surgery. Scanning time of the TSE sequence takes 100 s as opposed to 20 min using standard echo-planar DW MRI techniques without the requirement of a contrast agent and without the need for a general anaesthetic for any of the children. CONCLUSION: TSE (HASTE) DW MRI is emerging as a cost effective, noninvasive alternative to second look surgery for detection and screening for cholesteatoma in pediatric patients.