Accuracy of the bedside head impulse test in detecting vestibular hypofunction

Objective: To determine the accuracy of the bedside head impulse test ( bHIT) by direct comparison with results from the quantitative head impulse test ( qHIT) in the same subjects, and to investigate whether bHIT sensitivity and specificity changes with neuro- otological training. Methods: Video clips of horizontal bHIT to both sides were produced in patients with unilateral and bilateral peripheral vestibular deficits ( n = 15) and in healthy subjects ( n = 9). For qHIT, eye and head movements were recorded with scleral search coils on the right eye and the forehead. Clinicians ( neurologists or otolaryngologists) with at least 6 months of neuro- otological training (" experts'': n = 12) or without this training ("non- experts'': n = 45) assessed video clips for ocular motor signs of vestibular deficits on either side or of normal vestibular function. Results: On average, bHIT sensitivity was significantly ( t test: p< 0.05) lower for experts than for non- experts ( 63% vs 72%), while bHIT specificity was significantly higher for experts than non- experts ( 78% vs 64%). This outcome was a consequence of the experts' tendency to accept bHIT with corresponding borderline qHIT values as still being normal. Fitted curves revealed that at the lower normal limit of qHIT, 20% of bHIT were rated as deficient by the experts and 37% by the non- experts. Conclusions: When qHIT is used as a reference, bHIT sensitivity is adequate and therefore clinically useful in the hands of both neuro- otological experts and non- experts. We advise performing quantitative head impulse testing with search coils or high speed video methods when bHIT is not conclusive.