An algorithm for neurotologic disorders.

In the evaluation of patients with complaints of dizziness, hearing loss, and/or tinnitus, the primary objective is to determine the site of the lesion. An accurate localization of the lesion is important for selecting the most appropriate radiologic study. The information obtained from the vestibular and audiometeric evaluations identifies the site of the lesion accurately. For the vestibular evaluation we use photoelectric nystagmography (PENG) and the Torok monothermal differential caloric test. The initial audiometeric evaluation consists of a pure-tone audiogram and speech discrimination scores. Additional audiometric site-of-lesion tests and ABR are used selectively as the diagnostic yield of these tests does not significantly add to the information already obtained from the vestibular evaluation. If the lesion is suspected to lie in the middle ear or internal auditory canals, we use pluridirectional tomography. For further delineation of lesions confined to the internal auditory canal we use pneumo-CT. For suspected morphologic lesions of the posterior fossa we use thin-section CT with enhancement. Review has proved useful in defining petrous apex and skull base lesions. CT-rBBC studies have proved valuable in objectively demonstrating a deficient perfusion of the brain. The vascularity of certain lesions such as glomus tumors can be satisfactorily confirmed by this technique.