Department of Clinical Neuroscience, Division of Eye and Vision, Marianne Bernadotte Centrum, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden.
Invest Ophthalmol Vis Sci. 2024 Apr 1;65(4):26. doi: 10.1167/iovs.65.4.26.
Post-concussion syndrome (PCS) is commonly associated with dizziness and visual motion sensitivity. This case-control study set out to explore altered motion processing in PCS by measuring gaze stabilization as a reflection of the capacity of the brain to integrate motion, and it aimed to uncover mechanisms of injury where invasive subcortical recordings are not feasible.
A total of 554 eye movements were analyzed in 10 PCS patients and nine healthy controls across 171 trials. Optokinetic and vestibulo-ocular reflexes were recorded using a head-mounted eye tracker while participants were exposed to visual, vestibular, and visuo-vestibular motion stimulations in the roll plane. Torsional and vergence eye movements were analyzed in terms of slow-phase velocities, gain, nystagmus frequency, and sensory-specific contributions toward gaze stabilization.
Participants expressed eye-movement responses consistent with expected gaze stabilization; slow phases were fastest for visuo-vestibular trials and slowest for visual stimulations (P < 0.001) and increased with stimulus acceleration (P < 0.001). Concussed patients demonstrated increased gain from visual input to gaze stabilization (P = 0.005), faster slow phases (P = 0.013), earlier nystagmus beats (P = 0.003), and higher relative visual influence over the gaze-stabilizing response (P = 0.001), presenting robust effect sizes despite the limited population size.
The enhanced neural responsiveness to visual motion in PCS, combined with semi-intact visuo-vestibular integration, presented a subcortical hierarchy for altered gaze stabilization. Drawing on comparable animal trials, findings suggest that concussed patients may suffer from diffuse injuries to inhibiting pathways for optokinetic information, likely early in the visuo-vestibular hierarchy of sensorimotor integration. These findings offer context for common but elusive symptoms, presenting a neurological explanation for motion sensitivity and visual vertigo in PCS.
脑震荡后综合征（PCS）常伴有头晕和视觉运动敏感。本病例对照研究旨在通过测量眼球稳定度来探索 PCS 中运动处理的变化，以此反映大脑整合运动的能力，并揭示在无法进行皮质下侵入性记录的情况下的损伤机制。
研究共分析了 10 名 PCS 患者和 9 名健康对照者在 171 次试验中的 554 次眼动。在头戴式眼动追踪器的记录下，参与者在滚轴平面中接受视觉、前庭和视前庭运动刺激，以测量视动和前庭眼反射。对扭转和聚散眼动进行慢相速度、增益、眼震频率以及对眼球稳定的感觉特异性贡献的分析。
参与者的眼动反应符合预期的眼球稳定度；视前庭试验的慢相速度最快，视觉刺激最慢（P<0.001），且随刺激加速而增加（P<0.001）。脑震荡患者在视觉输入到眼球稳定的增益增加（P=0.005）、慢相速度加快（P=0.013）、眼震起始更快（P=0.003）以及相对视觉对眼球稳定反应的影响更高（P=0.001），尽管研究人群规模有限，但仍呈现出显著的效应量。
PCS 中对视觉运动的神经反应增强，加上半完整的视前庭整合，呈现出改变的眼球稳定的皮质下层次结构。基于类似的动物试验，研究结果表明，脑震荡患者可能遭受了对视动信息抑制通路的弥漫性损伤，可能发生在视前庭感觉运动整合的早期。这些发现为常见但难以捉摸的症状提供了背景，为 PCS 中的运动敏感和视觉性眩晕提供了神经学解释。
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