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Transcranial Hearing Aid Effective, Well Tolerated in Single-Sided Hearing Loss: Presented at AAO-HNSF

By Paula Moyer
Special to DG News

SAN DIEGO, CA -- September 26, 2002 -- Patients with single-sided sensorineural hearing loss report high satisfaction with a hearing device that replicates stereoscopic sound by means of transcranial contralateral cochlear stimulation, according to an American study.

"People who have unilateral deafness have been unmanaged for so long," said Dr. Wazen, associate professor of otolaryngology, Columbia University and chief of otology at Manhattan Eye and Ear Hospital in New York. "Hearing from both sides of our head is a natural condition. If we are able to reproduce that capability through a simple procedure, we would be most helpful to patients with single-sided deafness."

Dr. Soha Ghossaini, an otology/neurotology fellow at Columbia Presbyterian Hospital and co-investigator, presented the findings of a study on the transcranial contralateral choclear stimulator here September 24^th at the 106^th annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery Foundation.

Noting that poor patient satisfaction is associated with an earlier device, a hearing aid that works by contralateral routing of the sound signal (CROS), Drs. Wazen and Ghossaini sought to evaluate the effectiveness of the bone anchored cochlear stimulator (BAHA).

A titanium electrode is attached to the cranial bone behind the patient's deaf ear, and the hearing device snaps onto the electrode. The patient receives local anaesthesia for the implantation procedure, which is performed in an outpatient setting, said Dr. Wazen. When no hearing amplification is desired, such as at bedtime, the patient snaps the device off. The device works by routing sound signals transcranially, through the resonance of the skull bones, from the deaf side so that the cochlea of the good ear is stimulated.

The study enrolled 18 patients with unilateral deafness, with hearing thresholds exceeding 20-decibel speech reception threshold (SRT) in their hearing ear. All patients underwent a one-month pre-implantation trial with a contralateral routing hearing aid.

After implantation, the patients compared the performance of the bone anchored cochlear stimulator with the contralateral hearing aid. Areas assessed included speech reception thresholds in quiet settings and speech recognition performance in settings with noise. Patients also responded to two questionnaires, the Abbreviated Profile Hearing Benefit questionnaire and the Single Sided Deafness questionnaire. These focused on ease of conversation, reverberation, background, and aversiveness of sounds.

Patients experienced no major complications after undergoing implantation. They consistently reported a significant improvement in speech intelligibility in noise-filled environment and reported greater benefit from the transcranial cochlear stimulator compared to the contralateral hearing aid, Dr. Ghossaini said.

"In this patient base, 70 percent wore the transcranial cochlear stimulator seven days a week," she said. "When assessing the ability to converse at a dinner table with a companion sitting on their deaf side, 88 percent said the stimulator was better than the contralateral hearing aid. The average satisfaction score was 8 on a scale of 1 to 10, with 10 as the best possible score."

However, 64 percent of patients found no improvement in sound localization, Dr. Ghossaini noted.

The BAHA device was approved in early September for the indication of single-sided hearing loss. It is manufactured by Entific Systems, which funded the study. Both Drs. Wazen and Ghossaini have no proprietary interest in the company.

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