Bedside Vestibular Examination: Oculomotor, Positional, and Head Impulse Testing
Oculomotor battery
Begin with visual acuity, pupils, and alignment. Test smooth pursuit, saccades, and gaze holding. Saccadic pursuit and dysmetric saccades suggest cerebellar or brainstem disease. Check for spontaneous nystagmus with and without fixation (Frenzel or ophthalmoscopy), and for gaze-evoked nystagmus, which is central. The head impulse test assesses the angular VOR: with the patient fixating a target, turn the head rapidly 10-20 degrees and look for a corrective saccade. A positive test indicates a deficient VOR on that side.
Positional testing
Dix-Hallpike moves the patient from sitting to supine with the head turned 45 degrees and extended 20 degrees, testing the posterior canal. A positive response is a latency of seconds, upbeat-torsional nystagmus, and fatigability. The supine roll test turns the head 90 degrees each way in supine to test the horizontal canal; geotropic nystagmus is more intense on the affected side, while apogeotropic suggests cupulolithiasis or an anterior arm variant.
Head impulse nuances
Covert saccades occur during the head turn and can mask a deficit; overt saccades occur after. In acute vestibulopathy, a positive head impulse supports a peripheral lesion, but a normal impulse in severe vertigo raises concern for stroke. Skew deviation is tested with alternate cover; vertical misalignment suggests a central lesion.
Common traps
Performing Dix-Hallpike too slowly, missing latency, or testing only one side. Confusing the direction of nystagmus with the affected canal. Failing to remove fixation, which suppresses peripheral nystagmus.
Worked example
A patient reports brief vertigo when rolling over in bed. Supine roll to the right produces geotropic nystagmus stronger on the right. This indicates right horizontal canal canalithiasis; the affected side is the one with the stronger response.