Chiarovano Elodie, Vidal Pierre-Paul, Magnani Christophe, Lamas Georges, Curthoys Ian S, de Waele Catherine
CNRS UMR 8257, Cognition and Action Group, Centre Universitaire des Saints-Pères, Université Paris Descartes, Paris, France; ENT Department, Salpetriere Hospital, Paris, France.
CNRS UMR 8257, Cognition and Action Group, Centre Universitaire des Saints-Pères, Université Paris Descartes , Paris , France.
Front Neurol. 2016 Jan 25;7:4. doi: 10.3389/fneur.2016.00004. eCollection 2016.
Falls in seniors are a major public health problem. Falls lead to fear of falling, reduced mobility, and decreased quality of life. Vestibular dysfunction is one of the fall risk factors. The relationship between objective measures of vestibular responses and age has been studied. However, the effects of age on vestibular perception during caloric stimulation have not been studied. Twenty senior subjects were included in the study, and separated in two groups: 10 seniors reporting postural instability (PI) and exhibiting absence of vestibular perception when they tested with caloric stimulation and 10 sex- and age-matched seniors with no such problems (controls). We assessed vestibular perception on a binary rating scale during the warm irrigation of the caloric test. The function of the various vestibular receptors was assessed using video head impulse test (vHIT), caloric tests, and cervical and ocular vestibular-evoked myogenic potentials. The Equitest was used to evaluate balance. No horizontal canal dysfunction assessed using both caloric test and vHIT was detected in either group. No significant difference was detected between PI and control groups for the peak SPV of caloric-induced ocular nystagmus or for the HVOR gain. All the controls perceived rotation when the maximal SPV during warm irrigation was equal to or ≥15°/s. None of the subjects in the PI group perceived rotation even while the peak SPV exceeded 15°/s, providing objective evidence of normal peripheral horizontal canal function. All the PI group had abnormal Equitest results, particularly in the two last conditions. These investigations show for the first time that vestibular perception can be absent during a caloric test despite normal horizontal canal function. We call this as dissociation vestibular neglect. Patients with poor vestibular perception may not be aware of postural perturbations and so will not correct for them. Thus, falls in the elderly may result, among other factors, from a vestibular neglect due to an inappropriate central processing of normal vestibular peripheral inputs. That is, failure to perceive rotation during caloric testing when the SPV is >15°/s, should prompt the clinician to envisage preventive actions to avoid future falls such as rehabilitation.
老年人跌倒问题是一个重大的公共卫生问题。跌倒会导致害怕跌倒、行动能力下降以及生活质量降低。前庭功能障碍是跌倒的风险因素之一。人们已经对前庭反应的客观测量指标与年龄之间的关系进行了研究。然而，年龄对冷热试验期间前庭感知的影响尚未得到研究。本研究纳入了20名老年受试者，并将他们分为两组：10名报告有姿势不稳（PI）且在冷热试验中表现出无前庭感知的老年人，以及10名年龄和性别匹配且无此类问题的老年人（对照组）。在冷热试验的温水冲洗过程中，我们采用二元评分量表评估前庭感知。使用视频头脉冲试验（vHIT）、冷热试验以及颈肌和眼肌前庭诱发肌源性电位评估各种前庭感受器的功能。使用Equitest评估平衡功能。两组中通过冷热试验和vHIT评估均未检测到水平半规管功能障碍。PI组和对照组在冷热诱发眼震的最大慢相速度峰值或头眼视动反射增益方面均未检测到显著差异。当温水冲洗期间的最大慢相速度峰值等于或≥15°/秒时，所有对照组受试者都能感知到旋转。即使最大慢相速度峰值超过15°/秒，PI组的所有受试者也均未感知到旋转，这为外周水平半规管功能正常提供了客观证据。所有PI组的Equitest结果均异常，尤其是在最后两种情况下。这些研究首次表明，尽管水平半规管功能正常，但在冷热试验期间仍可能无前庭感知。我们将此称为分离性前庭忽视。前庭感知较差的患者可能意识不到姿势扰动，因此不会对其进行纠正。因此，老年人跌倒可能是由于正常前庭外周输入的中枢处理不当导致前庭忽视等多种因素引起的。也就是说，当最大慢相速度>15°/秒时在冷热试验中未能感知到旋转，应促使临床医生考虑采取预防措施以避免未来跌倒，如康复治疗。
