Vestibular evoked myogenic potentials and distortion-product otoacoustic emissions combined with glicerol testing in endolymphati c hydrops: their value in early diagnosis

OBJECTIVES: We describe the case of a young girl in whom transient deafness occurred when her core body temperature rose. METHODS: The patient was referred for a series of audiological and neurologic evaluations performed over time in both afebrile and febrile states, as well as after a stress test (with a treadmill) in which the body temperature rise simulated the febrile state. RESULTS: The patient was found to have a temporary bilateral hearing loss, but had normal distortion product otoacoustic emissions. Moreover, auditory brain stem responses revealed the absence of neural synchrony when her core body temperature increased. CONCLUSIONS: These results are consistent with a temperature-dependent auditory neuropathy, a rare condition in which patients show normal outer hair cell function and abnormal neural function of the eighth cranial nerve. The symptom is reminiscent of Uhthoff's phenomenon, which is described as transient visual loss and is usually observed in multiple sclerosis. This case of temperature-dependent auditory neuropathy is noteworthy because it sheds light on a disorder of which there have been few reports in the literature. We discuss its similarity to Uhthoff's phenomenon.