Читать книгу Vestibular Disorders - Группа авторов - Страница 44

The traditional caloric test is administered bithermally, wherein the patient’s ears are irrigated with both a warm and cool stimulus and then analyzed [9]. Unfortunately, the full bithermal battery is time-consuming (and therefore, costly) to administer and caloric testing can be a source of patient discomfort. Recent studies have examined the potential utility of a monothermal screen by retrospectively comparing the results of the warm and/or cool screen to the results from the bithermal test. Most have shown that a monothermal warm screen can be used to reduce the testing time and patient discomfort for a large proportion of patients and can be accomplished with a very low false-negative rate [10–14]. To optimize the predictive accuracy of the monothermal test, a warm screen is preferable to a cool screen [10–15].

To guarantee the value of the monothermal warm screen, a high sensitivity (low false-negative rate) is essential. The specificity for the monothermal warm screen is generally quite low [13]; this is of little consequence because patients whose inter-ear difference (IED) values exceed the determined normal criterion for the warm screen continue to complete the entire bithermal test. According to a recent systematic review of the literature by Adams et al., when a bithermal unilateral weakness (sometimes referred to as canal paresis) cut-off of 20 or 25% is assumed, an IED criterion set at ≤15% for the monothermal screen achieved a low false-negative rate (≤5%) and reduced the number of patients requiring the full bithermal caloric test to between 49 and 57% [16]. Establishing a minimum SPV value (<11 deg/s) for each irrigation [16] and excluding/adjusting for significant spontaneous nystagmus [12] may also improve the sensitivity of the results, though further investigation is needed.