The active head-impulse test in unilateral peripheral vestibulopathy.
BACKGROUND
The head-impulse test, which is sensitive and specific for detecting severe unilateral peripheral vestibulopathy, is an accepted part of the neurological examination, especially in patients with vertigo and balance disorders.


OBJECTIVE
To discover if the head-impulse test is just as useful diagnostically when patients are asked to rotate their own heads, the active head-impulse test, rather than when the clinician does so as in the standard passive head-impulse test.


METHODS
Clinical observation of compensatory saccades and search coil measurement of compensatory eye rotations, during active and passive horizontal head-impulses in 6 patients with total unilateral vestibular deafferentation.


RESULTS
Clinical observation showed the expected compensatory saccades with rotations toward the side with the lesion with passive head-impulses but not with active head-impulses. Search coil recordings revealed 2 reasons for this. With active head-impulses not only was vestibulo-ocular reflex gain higher, but compensatory saccade latency was shorter resulting in an occult saccade that occurred during, rather than after, head rotation.


CONCLUSIONS
Passive head-impulses are necessary to detect a severe unilateral peripheral vestibulopathy; active head-impulses will produce a false-negative result.
Black
Ross A
RA
Department of Neurology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Sydney, Australia. rossb@icn.usyd.edu.au
Halmagyi
G Michael
GM
Thurtell
Matthew J
MJ
Todd
Michael J
MJ
Curthoys
Ian S
IS
D000328:Adult; D000368:Aged; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D004574:Electromagnetic Fields; D005133:Eye Movements / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006257:Head / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012399:Rotation; D013997:Time Factors; D014724:Vestibular Function Tests; D020338:Vestibular Neuronitis / Q000175:diagnosis / Q000503:physiopathology*