面神经ENoG和MEP检查在面肌麻痹诊断及预后方面的应用

Application of Facial Nerve ENoG and MEP in the Diagnosis and Prognosis of Facial Nerve Palsy

应用面神经电图(ENoG)和面神经运动诱发电位(MEP),对60名正常人(ENoG30名,MEP30名)和40例面肌麻痹患者(ENoG20例,MEP20例)的测试结果表明:①ENoG是1种客观的电生理诊断技术,能较准确地反映面神经纤维状态,对诊断和判断预后有指导意义。但在面肌麻痹早期,仅靠此项检查来判断预后不够,还需结合其它电生理检查。②MEP是1种新的测试方法,能通过颅骨刺激到颅内近端面神经,对了解近端面神经状态大有帮助。初步研究表明,该技术安全、可靠,诱发电位重复性好,正常人与患者间差异显著。③两种方法结合使用,有助于早期了解病变的性质和程度,较全面地了解面神经的完整性,对判断预后,拟定治疗方案有重要意义。

Electroneurography (ENoG) , an objective electrophysiologic measurement of compound muscle action potentials (CMAPs), is used to assess the integrity of a peripheral motor nerve. This method has been used for many years. In our study using an electrophysiologic instrument (Medelec MS6), the stimulating electrode was placed over the facial nerve anterior to the tip of the mastoid process and was manipulated to obtain the maximum CMAPs amplitude from the frontal muscle. With 30 normal subjects and 20 patients with facial nerve palsy, the results showed that the latencies and amplitudes were different between the two groups. Motor evoked potential (MEP) is a new method. Ipsilatera] facial muscles are excited by magnetic stimulation over the scalp when the coil is placed over the parieto-occipital region. Using a magnetic stimulator and EMG instrument (l500C4 DISA) , CMAPs from the orbicu-laris oris and frontal muscle were measured. In 30 normal subjects,the CMAPs were similar in form but of longer latency than those obtained with electrical stimulation (ENoG).In 20 patients with lateral facial nerve palsy due to Bell's palsy, Hunt's syndrome or trauma, the latencies on the lesion sides were apparently longer and the amplitudes much lower than in the normals.Our studies suggest that magnetic stimulation will detect facial nerves in the region inside the temporal bone where they cannot be touched by electrical stimulation from in front of mastoid process. The use of both ENoG and MEP methods together allows for accurate measurement of proximal facial nerve conduction and also provides some quanitative measurement; thus, we can detect conduction block or axonal degeneration early. This is important not only for diagnosis but also for evaluating treatments and prognoses.