Appraisal of the Video Head Impulse Test (vHIT) Contribution towards the Evaluation of the Vertiginous Patient

Introduction: The video head impulse test (vHIT) has potential advantages over the bed-side head impulse test (bHIT) in the evaluation of the vertiginous patient as it provides quantified measure of the VOR gain and can identify covert saccades. However, the extra cost, the anticipated waiting for the test to be conducted, and the training period required to achieve adequate performance justify close inspection of its added benefit towards patient`s diagnosis.

Methods: The study participants were 92 patients referred for diagnosis and treatment of vertigo. The benefit of the bHIT results towards the prediction of the vHIT outcome was examined employing the sensitivity, specificity, positive and negative predictive values parameters. All 49 positive bHIT tests and 49 randomly chosen negative bHIT tests out of 135 were included in the evaluation. The bHITs were carried out by three senior otolaryngologists and all the vHIT by a neurophysiologist with formal training in performing the test. For the purpose of this study several definitions of positive vHIT were adapted: gain<0.8 (A); presence of corrective saccades (B); gain <0.8 or presence of saccades (C); presence of saccades with latency < 170msec and amplitude > 50 degree/sec (D); gain <0.8 or presence of saccades with latency < 170msec and amplitude > 50 degree/sec (E).

Results:

Conclusions: Our results demonstrate the low prediction values and high false negative and false positive rates of the bHIT while employed alone in the evaluation of the dizzy patient. These results emphasize the need for including the vHIT as a measure for testing the vestibular system response to daily velocities and accelerations in the diagnostic workout of the patient suffering from vertigo.