Investigation of a novel completely-in-the-canal direct-drive hearing device: a temporal bone study.

HYPOTHESIS: Whether a prototype direct-drive hearing device (DHD) is effective in driving the tympanic membrane (TM) in a temporal bone specimen to enable it to potentially treat moderate-to-severe hearing loss. BACKGROUND: Patient satisfaction with air conduction hearing aids has been low because of sound distortion, occlusion effect, and feedback issues. Implantable hearing aids provide a higher quality sound but require surgery for placement. The DHD was designed to combine the ability of driving the ossicular chain with placement in the external auditory canal. METHODS: DHD is a 3.5-mm wide device that could fit entirely into the bony ear canal and directly drive the TM rather than use a speaker. A cadaveric temporal bone was prepared. The device developed in our laboratory was coupled to the external surface of the TM and against the malleus. Frequency sweeps between 300 Hz to 12 kHz were performed in 2 different coupling methods at 104 and 120 dB, and the DHD was driven with various levels of current. Displacements of the posterior crus of the stapes were measured using a laser Doppler vibrometer. RESULTS: The DHD showed a linear frequency response from 300 Hz to 12 kHz. Placement against the malleus showed higher amplitudes and lower power requirements than when the device was placed on the TM. CONCLUSION: DHD is a small completely-in-the-canal device that mechanically drives the TM. This novel device has a frequency output wider than most air conduction devices. Findings of the current study demonstrated that the DHD had the potential of being incorporated into a hearing aid in the future.

Stereotactic radiosurgery for vestibular schwannomas: a survey of current practice patterns of neurotologists.

OBJECTIVE: To evaluate the use of radiation by neurotologists practicing in the United States as a treatment modality for vestibular schwannomas (VSs). STUDY DESIGN: Cross-sectional survey. METHODS: We surveyed 302 members of the American Neurotology Society to assess the number of VS seen, the frequency with which radiation is used as a treatment modality, radiation training and experience, the impact of tumor size and patient age on treatment decisions, and radiation dose ultimately used by neurotologists. RESULTS: Responses were received from 43% (132/302) of surveyed neurotologists; of the respondents, 42% (54/132) perform stereotactic radiation. Approximately 58% (30/54) of those use gamma knife, and 44% (24/54) use Cyberknife; 36.7% of VS patients seen by neurotologists received radiation. On average, 6 additional neurotologists per year begin treating VS with stereotactic radiation. Academic and private neurotologists showed significant differences (p < 0.05) between new VS patients per year, years in practice, and maximum tumor size recommended for radiation. The most common barrier to using radiation was prevention by a neurosurgical or radiation oncology service. Neurotologists use radiation to treat other cranial base tumors as well, most commonly glomus tumors or meningiomas, and 64% of respondents irradiate neurofibromatosis Type 2. Total radiation dose and fractionation were variable. CONCLUSION: Neurotologists are increasingly choosing to treat VS with stereotactic radiation. There seem to be significant differences between academic and private neurotologists' practice characteristics. Not all neurotologists strictly adhere to the consensus statement by the International RadioSurgery Association with regard to radiation dosing and tumor size limits.