Borel Liliane, Honoré Jacques, Bachelard-Serra Mathilde, Lavieille Jean-Pierre, Saj Arnaud
Cognitive Neurosciences Laboratory, UMR 7291, Aix Marseille University, CNRS, Marseille, France.
SCALab, UMR 9193, University of Lille, CNRS, Lille, France.
Front Syst Neurosci. 2021 Oct 27;15:733684. doi: 10.3389/fnsys.2021.733684. eCollection 2021.
The unilateral vestibular syndrome results in postural, oculomotor, perceptive, and cognitive symptoms. This study was designed to investigate the role of vestibular signals in body orientation representation, which remains poorly considered in vestibular patients. The subjective straight ahead (SSA) was investigated using a method disentangling translation and rotation components of error. Participants were required to align a rod with their body midline in the horizontal plane. Patients with right vestibular neurotomy (RVN; =8) or left vestibular neurotomy (LVN; = 13) or vestibular schwannoma resection were compared with 12 healthy controls. Patients were tested the day before surgery and during the recovery period, 7 days and 2 months after the surgery. Before and after unilateral vestibular neurotomy, i.e., in the chronic phases, patients showed a rightward translation bias of their SSA, without rotation bias, whatever the side of the vestibular loss. However, the data show that the lower the translation error before neurotomy, the greater its increase 2 months after a total unilateral vestibular loss, therefore leading to a rightward translation of similar amplitude in the two groups of patients. In the early phase after surgery, SSA moved toward the operated side both in translation and in rotation, as typically found for biases occurring after unilateral vestibular loss, such as the subjective visual vertical (SVV) bias. This study gives the first description of the immediate consequences and of the recovery time course of body orientation representation after a complete unilateral vestibular loss. The overall evolution differed according to the side of the lesion with more extensive changes over time before and after left vestibular loss. It is noteworthy that representational disturbances of self-orientation were highly unusual in the chronic stage after vestibular loss and similar to those reported after hemispheric lesions causing spatial neglect, while classical ipsilesional biases were reported in the acute stage. This study strongly supports the notion that the vestibular system plays a major role in body representation processes and more broadly in spatial cognition. From a clinical point of view, SSA appeared to be a reliable indicator for the presence of a vestibular disorder.
单侧前庭综合征会导致姿势、动眼、感知和认知症状。本研究旨在探讨前庭信号在身体方位表征中的作用，而这在前庭疾病患者中一直未得到充分考虑。采用一种分离误差的平移和旋转成分的方法对主观直线方向（SSA）进行了研究。参与者被要求在水平面内将一根杆与身体中线对齐。将右侧前庭神经切断术（RVN；n = 8）或左侧前庭神经切断术（LVN；n = 13）患者或前庭神经鞘瘤切除术患者与12名健康对照者进行比较。在手术前一天以及术后7天和2个月的恢复期对患者进行测试。在单侧前庭神经切断术前后，即在慢性期，无论前庭丧失的是哪一侧，患者的SSA都表现出向右的平移偏差，而无旋转偏差。然而，数据表明，神经切断术前的平移误差越低，单侧前庭完全丧失后2个月其增加幅度就越大，因此导致两组患者向右的平移幅度相似。在术后早期，SSA在平移和旋转方面均向手术侧移动，这与单侧前庭丧失后出现的偏差（如主观视觉垂直（SVV）偏差）的典型情况相同。本研究首次描述了完全单侧前庭丧失后身体方位表征的即时后果和恢复时间进程。总体演变因病变侧不同而有所差异，左侧前庭丧失前后随时间的变化更为广泛。值得注意的是，自我定向的表征障碍在前庭丧失后的慢性期非常少见，类似于半球病变导致空间忽视后所报道的情况，而在急性期则报道有典型的同侧偏差。本研究有力地支持了前庭系统在身体表征过程中以及更广泛地在空间认知中起主要作用的观点。从临床角度来看，SSA似乎是前庭疾病存在的可靠指标。
