Allum John H J, Scheltinga Alja, Honegger Flurin
*Division of Audiology and Neurootology, Department of ORL, University of Basel Hospital, Switzerland †Radboud University, Nijmegen, The Netherlands.
Otol Neurotol. 2017 Dec;38(10):e531-e538. doi: 10.1097/MAO.0000000000001477.
Patients with an acute unilateral peripheral vestibular deficit (aUPVD), presumed to be caused by vestibular neuritis, show asymmetrical vestibular ocular reflexes (VORs) that improve over time. Questions arise regarding how much of the VOR improvement is due to peripheral recovery or central compensation, and whether differences in peripheral recovery influence balance control outcomes.
Thirty patients were examined at aUPVD onset and 3, 6, and 13 weeks later with four different VOR tests: caloric tests; rotating (ROT) chair tests performed in yaw with angular accelerations of 5 and 20 degrees/s; and video head impulse tests (vHIT) in the yaw plane. ROT and vHIT responses and balance control of 11 patients who had a caloric canal paresis (CP) more than 90% at aUPVD onset and no CP recovery (no-CPR) at 13 weeks in caloric tests were compared with those of 19 patients with CP recovery (CPR) to less than 30%, on average. Balance control was measured with a gyroscope system (SwayStar) recording trunk sway during stance and gait tasks.
ROT and vHIT asymmetries of no-CPR and CPR patients reduced over time. The reduction was less at 13 weeks (36.2% vs. 83.5% on average) for the no-CPR patients. The no-CPR group asymmetries at 13 weeks were greater than those of CPR patients who had normal asymmetries. The greater asymmetries were caused by weaker deficit side responses which remained deficient in no-CPR patients at 13 weeks. Contra-deficit side vHIT and ROT responses remained normal. For all balance tests, sway was slightly greater for no-CPR compared with CPR patients at aUPVD onset and 3 weeks later. At 13 weeks, only sway during walking eyes closed was greater for the no-CPR group. A combination of 5 degrees/s ROT and balance tests could predict at onset (90% accuracy) which patients would have no-CPR at 13 weeks.
These results indicate that for ROT and vHIT tests, central compensation is observed in CPR and no-CPR patients. It acts primarily by increasing deficit side responses. Central compensation provides approximately 60% of the VOR improvement for CPR patients. The rest of the improvement is due to peripheral recovery which appears necessary to reduce VOR asymmetry to normal at 13 weeks on average. Balance control improvement is more rapid than that of the VOR and marginally affected by the lack of peripheral recovery. Both VOR and balance control measures at onset provide indicators of future peripheral recovery. For these reasons VOR and balance control needs to be tested at aUPVD onset and at 13 weeks.
急性单侧外周前庭功能减退（aUPVD）患者，推测由前庭神经炎引起，其前庭眼反射（VOR）不对称，且随时间改善。关于VOR改善中有多少归因于外周恢复或中枢代偿，以及外周恢复的差异是否影响平衡控制结果，出现了一些问题。
30例患者在aUPVD发病时以及发病后3周、6周和13周接受了四种不同的VOR测试：冷热试验；在偏航方向以5度/秒和20度/秒的角加速度进行的旋转（ROT）椅试验；以及在偏航平面的视频头脉冲试验（vHIT）。将11例在aUPVD发病时冷热试验半规管麻痹（CP）超过90%且在13周时冷热试验无CP恢复（无CPR）患者的ROT和vHIT反应及平衡控制，与19例CP恢复（CPR）至平均低于30%的患者进行比较。使用陀螺仪系统（SwayStar）测量平衡控制，记录站立和步态任务期间的躯干摆动。
无CPR和CPR患者的ROT和vHIT不对称性随时间降低。无CPR患者在13周时降低程度较小（平均分别为36.2%和83.5%）。无CPR组在13周时的不对称性大于不对称性正常的CPR患者。更大的不对称性是由于缺陷侧反应较弱，在13周时无CPR患者的缺陷侧反应仍不足。对侧缺陷侧vHIT和ROT反应保持正常。对于所有平衡测试，在aUPVD发病时和3周后，无CPR患者的摆动略大于CPR患者。在13周时，仅闭眼行走时无CPR组的摆动更大。5度/秒的ROT和平衡测试相结合可以在发病时（准确率90%）预测哪些患者在13周时无CPR。
这些结果表明，对于ROT和vHIT测试，在CPR和无CPR患者中均观察到中枢代偿。其主要作用是增加缺陷侧反应。中枢代偿为CPR患者提供了约60%的VOR改善。其余的改善归因于外周恢复，外周恢复似乎是平均在13周时将VOR不对称性降低至正常所必需的。平衡控制的改善比VOR更快，且受外周恢复缺乏的影响较小。发病时的VOR和平衡控制测量均提供了未来外周恢复的指标。因此，需要在aUPVD发病时和13周时测试VOR和平衡控制。
