A CLINICAL-EVALUATION OF HEAD IMPULSE TESTING

The head impulse test is a simple clinical test comprising high accele ration head rotation. In the presence of a severs unilateral vestibula r weakness the normal vestibulo-ocular reflex is replaced by a misalig nment of the eye followed by a series of corrective saccades which are evident to the examiner. Previous reports have shown the high sensiti vity of the head impulse test in detecting complete unilateral weaknes s, but indicate poor sensitivity for mild weaknesses. This prospective , blinded study examined the head impulse test in a general clinical p opulation of balance disorder patients to examine the sensitivity and specificity of the test, and to determine the degree of vestibular wea kness that is required before the test becomes positive. One hundred a nd fifty patients were examined and the head impulse :est results were compared to results from bithermal caloric testing. Results show that the overall sensitivity of the head impulse test is 34% with a specif icity of 100%. The test does not detect mild or moderate vestibular we aknesses but is very sensitive to the presence of a severe paresis (87 .5%). Head impulse testing will not replace caloric testing but is a v ery useful adjunct to it.