The role of vertical semicircular canal function in the vertical component of skull vibration-induced nystagmus

Background: Generally, vertical component of the skull vibratory nystagmus (VCN) is ignored in the clinical practise. Thus, the relative contribution of the vestibular organs in the presence of VCN remains unknown.

Objectives: To determine the association between vertical semicircular canal (vSCC) function and the presence of VCN.

Material and methods: Comparisons were made between Video Head Impulse Test and SVINT (100 Hz) results at the time of the acute peripheral vestibular lesion (PVL) and at the post-acute phase in patients diagnosed PVL. Later on, a paired analysis was performed restricting the assessments to patients with vestibular explorations in both the acute and post-acute phases.

Results: In an univariable analysis, larger mean total gain differences (TGD) between vSCC VOR gains, significantly related with the appearance of VCN in nystagmography in the acute phase (p = .001), unlike the post-acute phase (p = .46). After a multivariate analysis, mean TGD was the only predictive factor of the VCN (p = .013). In the paired analysis, we found an increase in the post-acute phase mean TGD, approaching zero value.

Conclusions and significance: Global relation between all vertical canals has at least a contributory role in the presence of the vertical component of nystagmus in SVINT.