Cause of hearing loss emerges in patients with genetic disease

MR and CT can be the key to explaining sudden hearing loss. Explanations are most commonly associated with a benign tumor of the acoustic nerve, commonly called an acoustic neuroma but more appropriately described as a vestibular schwannoma. But radiologists may have to look elsewhere to find the answer in patients with a genetic disorder called von Hippel-Lindau disease. Again, however, MR may hold the key.

Research scheduled to be published in the July 4 issue of Journal of the American Medical Association notes that hearing loss may occur due to hemorrhage in the inner ear caused by tumors in the endolymphatic sac or inner ear. These endolymphatic sac tumors (ELSTs) are associated with significant dysfunction of hearing and balance, including sudden irreversible hearing loss.

Dr. John A. Butman, a staff neuroradiologist at the National Institutes of Health Clinical Center, examined clinical findings and audiologic data on 35 patients with von Hippel-Lindau disease, finding ELSTs in 38 ears.

"ELSTs typically are very rare but common in patients with this disease," he said.

The study did not address the effectiveness of surgical resection. Butman found, however, that in several small operative series, complete resection of ELSTs can be curative, can alleviate vestibular symptomatology, and can be performed with hearing preservation and minimal morbidity.

Butman and colleagues concluded in the JAMA article that serial clinical evaluations and high-resolution MR and CT imaging to detect small ELSTs or intralabyrinthine hemorrhage are warranted in patients with this genetic disease.

When looking for the causes of hearing loss, Butman advises radiologists to look first for a vestibular schwannoma. In the absence of that, he said MR can uncover pathologies of the labyrinth itself, as well as abnormal enhancement in the cochlea or vestibule, which may indicate labyrinthitis or a neoplasm. MR and CT are also very good at finding morphological abnormalities in the cochlea and vestibule and in regions of the vestibular