The caloric response in the contralateral ear in acoustic neuroma.

The caloric test response from the unaffected ear in a case of acoustic neuroma may be normal, hypoactive or hyperactive; each has a different pathophysiological connotation: a normal response is the anticipated finding; a hyperactive contralateral response is due to the presence of a large neuroma with brainstem compression; and a hypoactive response may result from several factors, such as lack of mental alertness during the test, drugs like barbiturates, raised intracranial tension, or the presence of bilateral neuromas.