Using a library of almost 1,000 skull bones collected for more than 30 years at the Johns Hopkins Medical Institutions, researchers have identified a consistent congenital basis for a rare but troubling disorder they discovered in which loud noises cause dizziness. Their findings are to be presented Feb. 17 at the Association for Research in Otolaryngology (ARO) meeting in St. Petersburg Beach, Fla.

Called "superior canal dehiscence syndrome" (SCDS), the disorder is caused by a hole, or dehiscence, in part of the skull's temporal bone that overlies an inner ear balance canal. Lloyd Minor, M.D., of the Johns Hopkins Center for Hearing and Balance, first discovered the disorder in 1995 and described it -- along with a treatment -- in 1998.

"Patients show specific symptoms, including vertigo -- the sense that the room is moving -- in response to loud music, the noisy environment of a sports event or the dial tone of a telephone," he says.

The bone collection used in his study, thought to be the most extensive of its kind in the world, was preserved by George T. Nager, M.D., past chair of the Hopkins School of Medicine's otolaryngology department. All specimens came from cadavers with varying medical problems. Minor and colleagues used them to study the possible cause and incidence of the disorder. "We found that if the temporal bone in one ear was thin, the second ear showed the same thinness, an indication that the weakness is likely to be congenital if not inherited," says Minor, associate professor of otolaryngology-head and neck surgery, biomedical engineering and neuroscience at Hopkins. His team examined 989 specimens and found four with holes and 18 with thin sections in the bone.

One of Minor's first SCDS patients described seeing stationary objects move back and forth when he sang in the shower. Eye tests showed that tones played in his ear stimulated circular and upward eye motion. (A vide
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Contact: Melissa Murray
mmurray@jhmi.edu
410-955-8668
Johns Hopkins Medical Institutions
8-Feb-1999