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Press Releases: Southern California

October 21, 2004

MRI should be the preferred test for evaluating sensorineural hearing loss

PASADENA, CA – A Kaiser Permanente study recommends magnetic resonance imaging (MRI) be the preferred test for evaluating asymmetric sensorineural hearing loss rather than auditory brainstem response (ABR) testing. Asymmetric sensorineural hearing loss, or unequal nerve hearing loss, may indicate the presence of a tumor on or near the auditory nerve along its path from the ear to the brain.

"About 10 percent of patients in our study with asymmetric sensorineural hearing loss were found to have causative lesions which were shown by MRI," said Roberto A. Cueva, MD, FACS, a specialist in neurotology/skull base surgery in the Department of Head and Neck Surgery, Kaiser Permanente San Diego, and the study's principal author. "Keeping magnetic resonance imaging use dependent upon auditory brainstem response results, as traditionally done, will result in missed or delayed diagnosis in 29 out every 1,000 patients screened."

The study, which was funded by Southern California Permanente Medical Group, is published in the October edition of Laryngoscope.

The most prevalent cause of asymmetric sensorineural hearing loss diagnosed by MRI examination is vestibular schwannoma (also known as acoustic neuroma), a slow-growing, benign tumor that develops from the balance and hearing nerves. The tumor originates from an overproduction of Schwann cells that support and insulate nerves.

Magnetic resonance imaging utilizes a combination of radio waves and magnetic fields to create three-dimensional, internal images of soft issues including the brain, spinal cord and muscle.

Auditory brainstem response monitors electrical responses beginning in the inner ear as they travel through the auditory and balance nerves to the brainstem. ABR is usually performed to help diagnose causes of hearing loss, and dizziness; and diseases, such as multiple sclerosis in which the protective covering of nerves is damaged.

"These findings are important because, even though MRI is more expensive than ABR, we recommend its use to achieve earlier tumor detection and better treatment results," said Cueva.

The study's other authors are Dr. Colin Cave, Northwest Permanente Medical Group; Dr. Daniel H. Morrison, University of New Mexico; Dr. Ray Hilsinger, Northern California Permanente Medical Group; Dr. Michael Ruckenstein; and Dr. Gary Press, Department of Radiology, Kaiser Permanente San Diego Medical Center.

About Kaiser Permanente
Kaiser Permanente is America's leading integrated health plan. Founded in 1945, it is a nonprofit, group practice prepayment program with Southern California headquarters in Pasadena, California. Kaiser Permanente serves the health care needs of 3.3 million members in Southern California. Today it encompasses the nonprofit Kaiser Foundation Health Plan, Inc., Kaiser Foundation Hospitals and their subsidiaries, and the for-profit Southern California Permanente Medical Group. Kaiser Permanente's Southern California Region includes more than 49,900 technical, administrative and clerical employees and caregivers, and more than 6,000 physicians representing all specialties. More information about Kaiser Permanente can be found at kaiserpermanente.org.