Feb. 28, 2001 ST. PAUL, MN – Tinnitus -– a ringing in the ears that affects millions of people -– may be related to visual as well as auditory brain activity, according to a study in the February 27 issue of Neurology, the scientific journal of the American Academy of Neurology. Researchers made the connection while studying the origin of this unwanted sound.
The study focused on eight patients with gaze-evoked tinnitus (GET), an unusual condition in which tinnitus loudness and pitch increase during lateral gaze. GET may develop after surgical removal of tumors of the auditory nerve. The researchers expect that the findings from their study of this rare condition will open the door to a broader understanding of the brain abnormalities that cause tinnitus.
As researchers mapped the brains of GET patients, they found an unexpected imbalance between the auditory and visual parts of the brain.
Normally, these different brain areas communicate with each other to determine which perception should be given priority. In normal subjects, lateral gaze suppresses auditory brain activity, but not so with GET patients. This failure of one sensory system to suppress the activity of another may be an important feature of tinnitus.
"This is the first research to show that a failure of the complicated way our brain systems talk to each other contributes to the cause of tinnitus. Tinnitus is not the simple problem we hoped for," said Alan H. Lockwood, MD, study co-author. Lockwood, Professor of Neurology, Nuclear Medicine and Communicative Disorders and Sciences at the State University of New York at Buffalo, and the Veterans Administration Western New York Healthcare System, also co-authored the first research which showed tinnitus sensations came from the brain in the central auditory system, and not the cochlea.
"It remains to be seen what other parts of the brain are involved in the cause of tinnitus," added Lockwood. "However, this is an important step in unraveling this complicated story."
Tinnitus is a perception of ringing or buzzing in the ears that affects 50 million people in the US according to the American Tinnitus Association. Tinnitus is more common in men and in people over the age of 65. Severe tinnitus is associated with depression, anxiety, sleep disruption and other symptoms that significantly impact patients' quality of life.
A neurologist is a medical doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system.
The American Academy of Neurology, an association of more than 17,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research.
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