Department of Plastic and Reconstructive Surgery, Shinshu University School of Medicine and Graduate School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
J Plast Reconstr Aesthet Surg. 2010 Jan;63(1):59-64. doi: 10.1016/j.bjps.2008.07.021. Epub 2008 Nov 14.
We have proposed a hypothetical mechanism to involuntarily sustain the effective eyelid retraction, which consists of not only voluntary but also reflexive contractions of the levator palpebrae superior muscle (LPSM). Voluntary contraction of fast-twitch fibres of the LPSM stretches the mechanoreceptors in Mueller's muscle to evoke trigeminal proprioception, which induces continuous reflexive contraction of slow-twitch fibres of the LPSM through the trigeminal proprioceptive nerve fibres innervating the mechanoreceptors in Mueller's muscle via the oculomotor neurons, as a tonic trigemino-oculomotor reflex. In the common skeletal mixed muscles, electrical stimulation of the proprioceptive nerve, which apparently connects the mechanoreceptors in muscle spindles to the motoneurons, induces the electromyographic response as the Hoffmann reflex. To verify the presence of the trigemino-oculomotor reflex, we confirmed whether intra-operative electrical simulation of the transverse trigeminal proprioceptive nerve on the proximal Mueller's muscle evokes an electromyographic response in the LPSM under general anaesthesia in 12 patients. An ipsilateral, phasic, short-latency response (latency: 2.8+/-0.3 ms) was induced in the ipsilateral LPSM in 10 of 12 subjects. As successful induction of the short-latency response in the ipsilateral LPSM corresponds to the Hoffmann reflex in the common skeletal mixed muscles, the present study is the first electromyographic verification of the presence of the monosynaptic trigemino-oculomotor reflex to induce reflexive contraction of the LPSM. The presence of the trigemino-oculomotor reflex may elucidate the unexplainable blepharoptosis due to surgery, trauma and tumour, all of which may damage the trigeminal proprioceptive nerve fibres to impair the trigemino-oculomotor reflex.
我们提出了一个假设性的机制来无意识地维持有效的眼睑提起，这个机制不仅包括提上睑肌的自愿收缩，还包括反射性收缩。提上睑肌快肌纤维的自愿收缩拉伸 Mueller 肌中的机械感受器，引起三叉神经本体感觉，通过支配 Mueller 肌机械感受器的三叉神经本体感觉纤维，通过动眼神经引起提上睑肌慢肌纤维的持续反射性收缩，作为一种紧张性三叉神经-动眼反射。在常见的骨骼肌混合肌中，对本体感觉神经的电刺激，显然将肌梭中的机械感受器与运动神经元连接起来，会引起肌电图反应，即 Hoffmann 反射。为了验证三叉神经-动眼反射的存在，我们在 12 名患者全身麻醉下，确认在近端 Mueller 肌上对横形三叉神经本体感觉神经进行术中电刺激是否会引起提上睑肌的肌电图反应。在 12 名受试者中的 10 名中，同侧出现了一个相性、短潜伏期的反应（潜伏期：2.8+/-0.3 ms）。由于同侧提上睑肌中短潜伏期反应的成功诱导与常见骨骼肌混合肌中的 Hoffmann 反射相对应，本研究是首次用电生理学方法验证单突触三叉神经-动眼反射引起提上睑肌反射性收缩的存在。三叉神经-动眼反射的存在可能阐明了由于手术、创伤和肿瘤引起的无法解释的眼睑下垂，所有这些都可能损伤三叉神经本体感觉纤维，从而损害三叉神经-动眼反射。
