PREVALENCE OF HEAD-SHAKING NYSTAGMUS IN PATIENTS ACCORDING TO THEIR DIAGNOSTIC CLASSIFICATION IN A DIZZINESS UNIT

Objective: In a previous publication, the authors documented the preva lence and characteristics of head-shaking nystagmus (HSN) in over 1300 consecutive dizzy patients during formal electronystagmography (ENG) at the combined Otologic Function Unit (OFU) of the Toronto and Mount Sinai Hospitals. This companion study was done to prospectively analyz e a subgroup of 300 patients with known clinical diagnoses belonging t o the senior author (J.R.). Methods: The prevalence of HSN in this ser ies of patients with a known diagnosis is prospectively compared to th e presence of HSN in a series of normal controls. Results: Results ind icate that HSN is seen significantly (p < .05) in those patients with peripheral vestibular dysfunction and that the more globally the perip heral vestibular disorder involves end-organ (i.e., Meniere's) or prim ary afferent-neuron function (i.e., vestibular neuronitis), the more l ikely HSN will be present. Conclusion: We further comment on the usefu lness of the head-shake test and its clinical relevance in the bedside examination of the dizzy patient.