Static cervico-ocular reflex in healthy humans

Abstract

Background

Dynamic cervico- (COR) and vestibulo-ocular reflex (VOR) contribute to stabilise visual images in the retina. The gain in dynamic COR is small in healthy individuals but increases in patients with vestibular dysfunction. Conversely, static COR has not been directly observed in healthy individuals.

Objectives

To elucidate the presence of static COR and quantify it in normal individuals in the roll plane.

Methods

Eleven healthy participants were included in the study. Eye torsions were measured using video oculography to evaluate the static COR induced by lateral neck flexion during a head-upright-with-body-tilt position at 15°, 30°, and 45°. The ocular counterroll (OCR) was compared during whole-body and head tilts to assess the influence of static COR on OCR.

Results

Static COR was significantly observed as eye torsion in the direction opposite to the body tilt. The head tilt OCR was significantly smaller than the whole-body tilt OCR to the right side but not to the left side.

Conclusion

Static COR exists in healthy individuals and tends to show higher amplitude as neck flexion stimulation increases.

Chinese Abstract

背景：动态颈椎反射 (COR) 和前庭眼反射 (VOR) 有助于稳定视网膜中的视觉图像。 动态 COR 的增益在健康个体中很小, 但对于前庭功能障碍患者会增加。 相反, 尚未直接观察到健康的人具有静态 COR。

目的：阐明静态 COR 在正常人中的存在, 并对处于滚动平面中的正常人将其进行量化。

方法：本研究包括 11 名健康参与者。 使用视频眼动描记术测量眼扭转, 评估头部直立而身体倾斜 15°、30° 和 45°时由侧颈屈曲引起的静态 COR。 比较在全身和头部倾斜期间的眼部反卷（OCR）, 评估静态 COR 对 OCR 的影响。

结果：经观察, 静态 COR 显然是与身体倾斜方向相反的眼扭转。 头部倾斜 OCR 明显小于全身向右倾斜而不是向左倾斜时的 OCR。

结论：静态 COR 存在于健康个体中, 并且当颈部屈曲刺激增加时趋向于表现出更高的振幅。

Keywords:

• Cervico-ocular reflex
• ocular counterroll
• vestibulo-ocular reflex
• vestibular dysfunction
• video oculography

Acknowledgements

The authors thank Editage (www.editage.com) for English language editing.

Ethical approval

This study, which involved human participants, was reviewed and approved by the ethical committee of Tokyo Medical and Dental University Hospital. All participants provided written informed consent to participate in this study.

Author contributions

The conception, design, and data acquisition were performed by TO, KH, and TT. Drafting and data analysis were performed by TO. KH and TT critically reviewed and revised the manuscript. All participated in the final approval of the work.

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest.

Data availability statement

The raw data supporting the conclusions of this article will be made available by the authors without undue reservation.

Additional information

Funding

This work was supported by JSPS KAKENHI [grant number JP21K09557].