The accuracy of the simultaneous binaural bithermal test in the diagnosis of acoustic neuroma.

Forty-three patients with a surgically confirmed unilateral acoustic neuroma were studied preoperatively with both alternate and simultaneous binaural bithermal caloric tests using horizontal lead electronystagmography. Twenty-four patients had a significant reduced vestibular response on the side of the tumor utilizing the alternate binaural bithermal calorization of Fitzgerald-Hallpike. The addition of the simultaneous binaural bithermal stimulus improved the diagnostic accuracy of caloric testing from 56% to 86%. The simultaneous test was of particular accuracy in diagnosing the inferior vestibular nerve neuroma. The simultaneous stimulus, which adds only six and one-half minutes to overall testing time, is felt to be a valuable adjunct to the alternate test of Fitzgerald-Hallpike.