Vestibular evoked myogenic potentials in evaluation of whiplash syndrome disability.

Objective: Whiplash is an acceleration-deceleration mechanism of energy transfer to the neck that may result from a rearend or side impact, predominantly in motor vehicle accidents but also from other mishaps. Vertigo and dizziness after whiplash injury are the most frequent, persistent and disabling symptoms, even in the absence of anatomical and cervical spine damage. Vestibular disturbances in whiplash patients have been widely investigated; nevertheless, physiopathology of vertigo and dizziness still remains an unsolved problem. The aim of our study was to demonstrate that cVEMPs (cervical Vestibular Evoked Myogenic Potentials) represent a valid and non-invasive technique able to investigate vestibular function, in particular the vestibulo-collic refl ex and macular function. Study design: We examined 25 patients affected by disabling post-whiplash injury by means of audiovestibular tests: audiometric and impedance tests, nystagmus evaluation, caloric test, dynamic posturography and cervical VEMPs. Data obtained were compared with those of a normal control group. Results: Audiological tests, impedance tests, nystagmus evaluation, and caloric tests were normal in all patients. Comparison of dynamic posturography values obtained in whiplash patients and in the normal control group demonstrated signifi cant differences in the Composite Equilibrium Score and Visual Component. Finally, cVEMPs were bilaterally absent in 72% of patients, unilaterally absent in 16% and present in 12%. C onclusions: Based upon neurophysiological evidence and our results, we can hypothesize that a concussion of the macular receptors takes place and that the maculae are more sensitive than the ampulla or cochlea receptor to this kind of injury. We conclude that cervical VEMPs represent a valid and non-invasive technique to evaluate disability after whiplash injury.