Monothermal caloric testing in the screening of vestibular function.

Introduction: The alternate binaural bithermal caloric test (ABBT) is the standard test for evaluation of the dizzy patient. Monothermal caloric testing (MT) has the potential benefits of reducing the administration time and patient discomfort. The goal of the present study was to investigate the role of MT screening in the prediction of ABBT results.

Methods: ABBT results of 218 patients having normal otoneurological examination, normal hearing, and normal electronystagmography (ENG) were retrospectively analyzed to generate norms for all subtests. These norms were then employed to calculate the sensitivity and specificity of MT for predicting normal ABBT in a group of 197 consecutive dizzy patients who were referred for vestibular testing.

Results: The best predictions of ABBT by MT results were achieved when ENG testing showed oculomotor integrity and no spontaneous, positional, or positioning nystagmus. Under these conditions, warm MT lateralization < 32% had 90% sensitivity and 92% specificity for the prediction of normal ABBT.

Discussion: When no pathology is detected in the other parts of the ENG, warm MT lateralization < 32% can indicate normal ABBT with a 10% probability for a false-negative result. This false negative rate precludes the routine use of warm MT in the clinical realm and its application as a screening tool for possible vestibular deficits in a generally healthy population like aviation or diving candidates. Higher sensitivity may be achieved by lowering the cut-off point of the response asymmetry required for the diagnosis of MT screening failure and the omission of directional preponderance diagnosis from the goals of the screening.