Affiliations: [a] Health Sciences Institute, Portuguese Catholic University, Lisbon, Portugal | [b] Translational Clinical Physiology Unit, Institute of Molecular Medicine, Faculty of Medicine, University of Lisbon, Portugal | [c] Otolaryngology Unit, Hospital de Cascais, Cascais, Portugal | [d] German Center for Vertigo and Balance Disorders, Munich University Hospital, Germany | [e] Department of Neurology, Munich University Hospital, Germany | [f] EMG and Motor Control Unit, Neurology Department, Hospital Clínic, Universitat de Barcelona, IDIBAPS, Spain | [g] Institute for Clinical Neurosciences, Munich University Hospital, Germany | [h] Institute of Medical Technology, Brandenburg University of Technology, Cottbus-Senftenberg, Germany
Correspondence:
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Corresponding author: Leonel Luis, Clinical Physiology Translational Unit, IMM, Faculty of Medicine, University of Lisbon, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal. Tel.: +351 935 345 051; E-mail:[email protected]
Abstract: BACKGROUND: Differentiating central from peripheral origins of
spontaneous nystagmus (SN) is challenging. Looking for a simple sign of
peripheral disease with the video Head Impulsive Test we noticed
anti-compensatory eye movements (AQEM) in patients with peripheral
etiologies of spontaneous nystagmus (SN). Here we assess the diagnostic
accuracy of AQEM in differentiating peripheral from central vestibular
disorders. METHODS: We recorded the eye movements in response to horizontal
head impulses in a group of 43 consecutive patients with acute
vestibular syndrome (12 with central, 31 with peripheral disorders), 5
patients after acute vestibular neurectomy (positive controls) and 39
healthy subjects (negative controls). AQEM were defined as quick eye
movements (peak velocity above 50°/s) in the direction of the head
movement. RESULTS: All patients with peripheral disorders and positive
controls had AQEM (latency 231 ± 53 ms, amplitude 3.4 ± 1.4°,
velocity 166 ± 55°/s) when their head was moved to the opposite side
of the lesion. Central patients did not have AQEM. AQEM occurrence rate was
higher in peripheral patients with contralesional (74 ± 4%, mean ± SD)
in comparison to ipsilesional (1 ± 4%) impulses (p< 0.001).
Overall diagnostic accuracy for differentiating central from peripheral
patients was 96% (95% CI for AUC ROC curve: 0.90 to 1.0) for VOR gain
and 100% (95% CI: 1.0 to 1.0) for AQEM occurrence rate. CONCLUSIONS: These results suggest that AQEM are a sign of
vestibular imbalance in a peripheral deficit. In addition to VOR gain they
should be added to the evaluation of the head impulse test.
Keywords: Neuro-otology, vestibulo-ocular reflex (VOR), vestibular function tests
