Bedside HST and SVINT as Clinical Indicators Associated with Caloric DP and UW: A Retrospective Exploratory Study

Background: Caloric testing provides quantitative measures of unilateral weakness (UW) and directional preponderance (DP). By contrast, skull vibration-induced nystagmus (SVINT) and the head-shaking test (HST) are bedside procedures that use different stimuli and operate within distinct temporal response domains. Objectives: This study was designed as a retrospective exploratory analysis of associations between categorical SVINT findings and caloric UW, and between categorical HST findings and caloric DP. Methods: We retrospectively evaluated 76 patients who underwent caloric testing, SVINT, and HST. Because the available records classified SVINT and HST only as present or absent, we restricted the analysis to associations between categorical findings and caloric classifications. Results: Pathological UW was associated with pathological SVINT, and pathological DP was associated with pathological HST. These findings are exploratory and do not demonstrate that the bedside procedures measure UW or DP, nor do they establish proportionality, physiological equivalence, interchangeability, or caloric-like quantitative information. Conclusions: SVINT and HST should therefore be interpreted as distinct and complementary bedside observations. Prospective studies with standardised quantitative eye-movement recordings are required to examine their temporal and physiological relationships with caloric responses.