Effect of head roll‐tilt on the subjective visual vertical in healthy participants: Towards better clinical measurement of gravity perception

Abstract

Objective: Gravity perception is an essential function for spatial orientation and postural stability; however, its assessment is not easy. We evaluated the head-tilt perception gain (HTPG, that is, mean perceptual gain [perceived/actual tilt angle] during left or right head roll-tilt conditions) and head-upright subjective visual vertical (SVV) using a simple method developed by us to investigate the characteristics of gravity perception in healthy participants. Methods: We measured the SVV and head roll-tilt angle during head roll-tilt within ±30 of vertical in the sitting and standing positions while the participant maintained an upright trunk (sitting, 434 participants; standing, 263 participants). We evaluated the head-upright SVV, HTPG, and laterality of the HTPG. Results: We determined the reference ranges of the absolute head-upright SVV (<2.5), HTPG (0.80-1.25), and HTPG laterality (<10%) for the sitting position. The head-upright SVV and HTPG laterality were not influenced by sex or age. However, the HTPG was significantly greater in women than in men and in middle-aged (30-64 years) and elderly (65-88 years) participants than in young participants (18-29 years). The HTPG, but not the head-upright SVV or HTPG laterality, was significantly higher in the standing vs sitting position. Conclusion: The HTPG is a novel parameter of gravity perception involving functions of the peripheral otolith and neck somatosensory systems to the central nervous system. The HTPG in healthy participants is influenced by age and sex in the sitting position and immediately increases after standing to reinforce the righting reflex for unstable posture, which was not seen in the head-upright SVV, previously considered the only parameter.

Gravity perception disturbance in patients with unilateral Meniere disease

“…The HT‐SVV test was performed using a simple examination system (HT‐SVV system, UNIMEC, Fuchu, Japan), that we developed as described previously. 1 The participants sat on a chair ~60 cm from a bar‐display box and wore goggles to eliminate any visual reference cues outside the bar. At the beginning of each trial, the participant was asked to tilt the head slowly leftward or rightward (approximately −30°, 0°, or 30° head tilt; 0° is upright, that is, in the direction of gravity, and rightward is positive), according to the examiner's instructions, while keeping the participant's trunk upright and their eyes closed.…”

“…In this study, the reference values were set for HTPG (0.80–1.25), HTPG AR (<10%), and HU‐SVV (<2.5°). 1 If any of these values were beyond the reference ranges, the diagnosis of GPD was confirmed. Based on the abnormal result of HTPG (HTPG and/or HTPG AR) and HU‐SVV, GPD was classified into the following three types.…”

“…Patients with vertigo/dizziness observed in clinical practice exhibit a variety of clinical features, including gravity perception disturbance (GPD). 1 GPD occurs when there is an anomaly in the gravity perception mechanism, which consists of the central nervous system, 2 , 3 , 4 , 5 that integrates sensory input from the otolith organs; 6 , 7 , 8 somatosensory receptors; 9 and semicircular canals. 10 GPD is diagnosed using the subjective visual vertical (SVV) test, 11 , 12 which is a simple psychophysical paradigm for measuring the visually perceived direction of the gravitational vertical using a visual line stimulus.…”

“…To examine GPD in more detail, we established the head‐tilt SVV test (HT‐SVV test), which is performed with the head upright and statically tilted to the left and right. 14 We have previously reported the results of the HT‐SVV test in healthy participants 1 and patients with vertigo/dizziness. 15 , 16 The HT‐SVV test assesses the left and right head‐tilt perception gains (HTPGs), which is a parameter used to evaluate the magnitude of gravity perception with the head statically tilted to the left and right, in addition to the HU‐SVV.…”

Data_Sheet_1.PDF

“…In the current study, we aimed to investigate whether vestibular functions in the reflex and cortical pathways could predict individual MS susceptibility. Specifically, vestibular functions in the reflex and cortex pathway were assessed using two clinical tests: the ocular counter-rolling (OCR) test for otolith-reflex sensitivity to detect linear acceleration (13,14,29,30) and the head-tilt subjective visual vertical (HT-SVV) test (31,33). There are a variety of tests that assess the bilateral asymmetry of otolith function.…”