Clinical and experimental results with focused ultrasound.

Focused ultrasound was applied at the lateral semicircular canal in 19 patients and at the round window in 12 patients, all of whom had intractable vertigo caused by Meniere's disease. Postoperatively, the vertigo was relieved or diminished in 75% of the lateral canal cases and in 25% of the round window cases. The results indicate that the lateral canal approach may have some therapeutic value, but the treatment is arduous for the patient and the risk of facial palsy is always nettlesome. Utilizing similar techniques, ultrasound irradiation was given to the lateral canals of 6 squirrel monkeys and to the round windows of 15 cats. After survival times of up to 3 months, light microscopic studies of the temporal bones of these animals show no morphological changes which can be attributed to the ultrasound irradiation. In general, these findings are in concert with the reports of other investigators and show that selective ablation of the vestibular sense organs cannot be achieved by current techniques of ultrasound irradiation. It seems doubtful that prolonged relief of vertigo can be expected to occur without a more complete morphological ablation of the vestibular sense organs than is possible with the current methods of ultrasound treatment.