Møller A R
Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pennsylvania 15213.
Exp Neurol. 1987 Oct;98(1):110-9. doi: 10.1016/0014-4886(87)90076-8.
Hemifacial spasm is a rare disorder that is caused by a blood vessel cross-compressing the facial nerve near the nerve's entry into the brain stem. Electrical stimulation of one branch of the facial nerve on the affected side in patients elicits a response from muscles that are innervated by another branch. Intraoperative recording of this abnormal muscle response, together with measurements of conduction times in parts of the facial nerve, in earlier studies have shown evidence that the cross-transmission of antidromic activity that causes this response occurs central to the site of vascular compression of the facial nerve. In this study we show that in rare circumstances during microvascular decompression operations, a small EMG potential precedes the regular abnormal muscle response. This early response has a latency that is equal to the sum of the conduction times of the portions of the facial nerve that would have been involved if the cross-transmission had occurred at the site of vascular compression of the facial nerve, and it may thus be a result of ephaptic transmission in the nerve at that location. Thus, cross-transmission of antidromic activity can indeed occur in the facial nerve at the site of compression, although we have observed this early potential in only 3 of more than 50 patients who were operated upon for hemifacial spasm; further, in those three patients it occurred only for a short time and only during surgical manipulation of the facial nerve. In view of the fact that this early response occurs only after the nerve has been manipulated, and because it is of such small magnitude, it seems unlikely that such cross-transmission (ephaptic transmission) at the site of the vascular compression plays a direct role in generating the spasm and the antidromic activity that spreads from one branch of the facial nerve to another.
面肌痉挛是一种罕见的疾病，由血管在面神经进入脑干附近对面神经进行交叉压迫所致。对患侧面神经的一个分支进行电刺激时，患者会引发受另一分支支配肌肉的反应。在早期研究中，术中记录这种异常肌肉反应，并测量面神经各部分的传导时间，结果显示，引起这种反应的逆向冲动的交叉传导发生在面神经血管压迫部位的中枢侧。在本研究中，我们发现在微血管减压手术的罕见情况下，在常规异常肌肉反应之前会出现一个小的肌电图电位。这种早期反应的潜伏期等于面神经各部分传导时间之和，而这些部分在面神经血管压迫部位发生交叉传导时会参与其中，因此它可能是该部位神经电突触传递的结果。所以，逆向冲动的交叉传导确实可以在面神经的压迫部位发生，尽管在接受面肌痉挛手术的50多名患者中，我们仅在3例患者中观察到了这种早期电位；此外，在这3例患者中，这种情况仅在短时间内出现，且仅在对面神经进行手术操作时出现。鉴于这种早期反应仅在神经受到操作后才出现，而且其幅度很小，血管压迫部位的这种交叉传导（电突触传递）似乎不太可能在引发痉挛以及从面神经一个分支传播到另一个分支的逆向冲动中起直接作用。
