Sindou M, Mercier P
University Lyon 1, domaine Rockefeller, 69000 Lyon, France; Groupe ELSAN, clinique Bretéché, 44000 Nantes, France.
CS74521, department of anatomy, faculté de Santé, 28, rue Roger-Amsler, 49045 Angers cedex 1, France.
Neurochirurgie. 2018 May;64(2):133-143. doi: 10.1016/j.neuchi.2018.04.003. Epub 2018 May 18.
Primary hemifacial spasm with few exceptions is due to the vascular compression of the facial nerve that can be evidenced with high resolution MRI. Microvascular decompression is the only curative treatment for this pathology. According to literature review detailed in chapter "conflicting vessels", the compression is located at the facial Root Exit Zone (REZ) in 95% of the cases, and in 5% distally at the cisternal or the intrameatal portion of the root as the sole conflict or in addition to one at brainstem/REZ. Therefore, exploration has to be performed on the entire root, from the ponto-medullary fissure to the internal auditory meatus. Because microvascular decompression is functional surgery, the procedure should be as harmless as possible and with a high probability of permanent efficacy. Besides facial palsy, main complications are hearing loss, tinnitus and gait disturbances. Causes are cochlea/labyrinth ischemia due to manipulations of their nutrient arteries and/or stretching of the eight nerve complex. To minimize the latter, the approach should not be with lateral-to-medial retraction of the cerebellar hemisphere, but along an infra-floccular trajectory, from below. In fact, most of the neurovascular conflicts are situated ventro-caudally to facial REZ at the brainstem, particularly those from a megadolicho-vertebrobasilar artery and its posterior inferior-cerebellar branch. Also, care should be taken not to cause any injury of the manipulated vessels or stretching of their perforators to brainstem. Heating from bipolar coagulation must be avoided. The inserted material used to maintain the offending vessel(s) away must not be neo-compressive. Intraoperative neuromonitoring is considered to be useful for achieving safe surgery at least until the learning curve has reached an optimal level, particularly BrainstemAuditory Evoked Potentials recordings. Increase in latency and/or decrease in amplitude of wave V warn excessive stretching or damage to the cochlear nerve, and decrease in amplitude of wave I signals possible ischemia of the cochlea. Free-running EMG of the facial muscles may warn against excessive manipulation of the facial nerve. Recording of the lateral spread responses - which are a sign of hyperexcitabilty of the facial motor system - may provide information on completeness of the decompression.
原发性面肌痉挛除少数情况外，是由于面神经受到血管压迫，这可通过高分辨率磁共振成像得以证实。微血管减压术是针对这种病症的唯一根治性治疗方法。根据“冲突血管”章节中详细的文献综述，95%的病例中压迫位于面神经根部出口区（REZ），5%的病例中压迫位于神经根的脑池段或内耳道段远端，这是唯一的冲突部位，或者除了脑干/REZ处的冲突之外还有此处的冲突。因此，必须对从脑桥延髓沟到内耳道的整个神经根进行探查。由于微血管减压术是功能性手术，该手术应尽可能无害且具有高概率的永久疗效。除了面神经麻痹外，主要并发症是听力丧失、耳鸣和步态障碍。其原因是在操作其营养动脉和/或牵拉第八神经复合体时导致的耳蜗/迷路缺血。为了尽量减少后者，手术入路不应采用小脑半球从外侧向内侧的牵拉，而应从下方沿着绒球下轨迹进行。实际上，大多数神经血管冲突位于脑干处面神经REZ的腹侧尾端，特别是来自巨大延长型椎基底动脉及其小脑后下分支的冲突。此外，应注意避免对被操作血管造成任何损伤或牵拉其穿支至脑干。必须避免双极电凝产生的热效应。用于将肇事血管推开的植入材料不得产生新的压迫。术中神经监测被认为有助于实现安全手术，至少在学习曲线达到最佳水平之前是如此，特别是脑干听觉诱发电位记录。波V潜伏期延长和/或波幅降低提示耳蜗神经过度牵拉或损伤，波I波幅降低提示耳蜗可能缺血。面肌自由运行肌电图可警示对面神经的过度操作。记录侧方扩散反应——这是面肌运动系统兴奋性增高的标志——可提供减压是否彻底的信息。
