Tilikete C, Vighetto A
Université Lyon I, Lyon, France.
Neurochirurgie. 2009 Apr;55(2):127-31. doi: 10.1016/j.neuchi.2009.01.003. Epub 2009 Mar 17.
The vestibular system detects head movements such as angular rotation, translation, and head position relative to gravity. It acts to stabilize the eyes and posture through subcortical reflexes. Its signals are also integrated at the cortical level to participate in the elaboration of a body scheme, used for different functions such as spatial orientation and motor control. The vestibular nerve shows a resting discharge rate that is modulated up or down according to head motion or position. Central functioning depends on the detection of an asymmetry between signals coming from a pair of peripheral sensors, one on either side. In pathological cases, unilateral peripheral dysfunction is interpreted by the central system as an asymmetry resulting from a change in head position leading to nystagmus, postural disturbances, and vertigo. The dysfunction can be either a deficit, such as observed in vestibular neuronitis, or hyperactivity such as observed in neurovascular compression syndrome of the VIIIth nerve. Anatomically, the VIIIth nerve has a long Root Entry Zone (REZ) that extends over 10mm before entering the brainstem. The VIIIth nerve is also physiologically close to numerous vessels at the pontocerebellar angle and internal auditory meatus. Therefore, vestibular syndrome resulting from neurovascular compression syndrome of the VIIIth nerve may exist, but it is very difficult to prove using radiological imagery.
前庭系统可检测头部运动，如角旋转、平移以及头部相对于重力的位置。它通过皮质下反射来稳定眼睛和姿势。其信号也在皮质水平进行整合，以参与身体图式的构建，用于空间定向和运动控制等不同功能。前庭神经具有静息放电率，该放电率会根据头部运动或位置上调或下调。中枢功能取决于检测来自一对外周传感器（两侧各一个）的信号之间的不对称性。在病理情况下，中枢系统将单侧外周功能障碍解释为头部位置变化导致的不对称，进而引发眼球震颤、姿势紊乱和眩晕。功能障碍可能是一种缺陷，如在前庭神经炎中观察到的那样，也可能是活动亢进，如在第八对脑神经的神经血管压迫综合征中观察到的那样。从解剖学角度来看，第八对脑神经有一个长的神经根进入区（REZ），在进入脑干之前延伸超过10毫米。第八对脑神经在生理上也与脑桥小脑角和内耳道的许多血管接近。因此，第八对脑神经的神经血管压迫综合征导致的前庭综合征可能存在，但使用放射影像学很难证实。
