Bertolini Giovanni, Romano Fausto, Straumann Dominik, Keller Katharine, Palla Antonella, Feddermann-Demont Nina
Swiss Concussion Center, Schulthess Clinic, Zurich, Switzerland.
Department of Neurology, University Hospital and University of Zurich, Frauenklinikstrasse 26, CH-8091, Zurich, Switzerland.
J Neurol. 2021 May;268(5):1747-1761. doi: 10.1007/s00415-020-10359-8. Epub 2020 Dec 26.
Concussed patients with chronic symptoms commonly report dizziness during exposure to environments with complex visual stimuli (e.g. supermarket aisles, busy crossroads). Such visual induced dizziness is well-known in patients with vestibular deficits, in whom it indicates an overreliance on visual cues in sensory integration. Considering that optokinetic after-nystagmus (OKAN) reflects the response of the central network integrating visual and vestibular self-motion signals (velocity storage network), we investigated OKAN in 71 patients [17 (23.9%) females, 30.36 ± 9.05 years old] who suffered from persistent symptoms after a concussion and presented clinical signs suggesting visual dependence. Data were retrospectively compared with 21 healthy individuals [13 (61.9%) females, 26.29 ± 10.00 years old]. The median values of the slow cumulative eye position and of the time constant of OKAN were significantly higher in patients than in healthy individuals (slow cumulative eye position: 124.15 ± 55.61° in patients and 77.87 ± 45.63° in healthy individuals-p = 0.012; time constant: 25.17 ± 10.27 s in patients and 13.95 ± 4.92 s in healthy individuals-p = 0.003). The receiving operating curve (ROC) estimated on the time constant had an overall area under the curve of 0.73. Analysis of the ROC suggests that a test measuring the OKAN time constant could obtain a sensitivity of 0.73 and specificity of 0.72 in determining the origin of the visual-related disturbances in those patients (threshold 16.6 s). In a subset of 43 patients who also performed the Sensory Organization Test (SOT), the proposed OKAN test was twice as sensitive as the SOT. This study suggests that concussed patients with persisting visual symptoms may have an underlying impairment of the velocity storage mechanism and that measuring the OKAN time constant can objectify such impairment.
患有慢性症状的脑震荡患者在接触具有复杂视觉刺激的环境（如超市过道、繁忙的十字路口）时，通常会报告头晕。这种视觉诱发的头晕在前庭功能缺损患者中很常见，这表明他们在感觉整合中过度依赖视觉线索。鉴于视动性眼震后效（OKAN）反映了整合视觉和前庭自我运动信号的中枢网络（速度存储网络）的反应，我们对71例患者[17例（23.9%）女性，年龄30.36±9.05岁]进行了OKAN研究，这些患者在脑震荡后出现持续症状，并表现出提示视觉依赖的临床体征。数据回顾性地与21名健康个体[13例（61.9%）女性，年龄26.29±10.00岁]进行了比较。患者的OKAN慢相累积眼位和时间常数的中位数显著高于健康个体（慢相累积眼位：患者为124.15±55.61°，健康个体为77.87±45.63°，p=0.012；时间常数：患者为25.17±10.27秒，健康个体为13.95±4.92秒，p=0.003）。根据时间常数估计的接受操作曲线（ROC）的曲线下总面积为0.73。ROC分析表明，在确定这些患者视觉相关障碍的起源时，测量OKAN时间常数的测试可获得0.73的敏感性和0.72的特异性（阈值为16.6秒）。在43例还进行了感觉组织测试（SOT）的患者子集中，所提议的OKAN测试的敏感性是SOT的两倍。这项研究表明，有持续视觉症状的脑震荡患者可能存在速度存储机制的潜在损害，并且测量OKAN时间常数可以使这种损害客观化。
