Ishikawa M, Ohira T, Namiki J, Kobayashi M, Takase M, Kawase T, Toya S
Department of Neurosurgery, School of Medicine, Keio University, Tokyo, Japan.
J Neurosurg. 1997 Apr;86(4):654-61. doi: 10.3171/jns.1997.86.4.0654.
In patients with hemifacial spasm, it has been said that the spasm is due to cross compression of the facial nerve by a blood vessel and that microvascular decompression (MVD) of the facial nerve is an effective treatment. The F waves, which result from backfiring of antidromically activated motor neurons of the facial motor nucleus, are indices of the excitability of the facial motor nucleus and are enhanced in patients with hemifacial spasm. Measuring blink reflexes and abnormal muscle responses (lateral spread), a characteristic sign of hemifacial spasm, has been used to investigate the mechanism of hemifacial spasm pathophysiologically. Thus the authors measured F waves of the facial muscle, blink reflexes, and abnormal muscle responses before and after MVD in patients suffering from hemifacial spasm to investigate the excitability of the facial motor nucleus and the course of the cure of hemifacial spasm after MVD. The authors obtained facial nerve-evoked electromyograms in 20 patients with hemifacial spasm before and after the MVD procedure. On the spasm side, the F waves and blink reflexes were enhanced preoperatively compared to those on the normal side and abnormal muscle responses were recorded in all patients. In 12 patients whose hemifacial spasm had not disappeared completely for 5.1 +/- 1.7 (mean +/- standard error) months following the MVD procedure, F waves were still enhanced significantly and abnormal muscle responses were still recordable, albeit at lower amplitude. Within 1 month after the hemifacial spasm had disappeared completely. F waves were still significantly enhanced in 17 patients and abnormal muscle responses were recorded in seven of 15 patients. Subsequently, the enhanced F waves and abnormal muscle responses disappeared completely. The authors' study supports the hypothesis that the cause of hemifacial spasm is hyperexcitability of the facial motor nucleus and suggests that additional surgery should not be performed for at least 2 years after MVD, because that period is necessary for the disappearance of the hyperexcitability of the facial motor nucleus.
在半面痉挛患者中，据说痉挛是由于血管对面神经的交叉压迫所致，而面神经微血管减压术（MVD）是一种有效的治疗方法。F波由面神经运动核的逆行激活运动神经元的回返放电产生，是面神经运动核兴奋性的指标，在半面痉挛患者中增强。测量眨眼反射和异常肌肉反应（侧向扩散），这是半面痉挛的一个特征性体征，已被用于从病理生理学角度研究半面痉挛的机制。因此，作者测量了半面痉挛患者在MVD术前和术后的面部肌肉F波、眨眼反射和异常肌肉反应，以研究面神经运动核的兴奋性以及MVD术后半面痉挛的治愈过程。作者在20例半面痉挛患者接受MVD手术前后获取了面神经诱发肌电图。在痉挛侧，术前F波和眨眼反射比正常侧增强，所有患者均记录到异常肌肉反应。在12例患者中，MVD术后5.1±1.7（平均±标准误）个月半面痉挛仍未完全消失，F波仍显著增强，异常肌肉反应仍可记录，尽管幅度较低。在半面痉挛完全消失后的1个月内，17例患者的F波仍显著增强，15例患者中有7例记录到异常肌肉反应。随后，增强的F波和异常肌肉反应完全消失。作者的研究支持半面痉挛的病因是面神经运动核兴奋性过高这一假说，并表明MVD术后至少2年内不应进行额外手术，因为这段时间是面神经运动核兴奋性过高消失所必需的。
