Résumé
ObjectiveTo study the methods of how to protect facial nerve function following complete resection of acoustic neurinomas and the value of the techniques of F wave assisted electrophysiological monitoring intraoperatively.Methods Retrospectivelysummarizing theresultsof combining three electrophysiological monitoring techniques such as nasal muscle F wave recording,online EMG and triggered EMG to monitor 46 cases of microoperations for acoustic neurinomas intraoperatively during the period of Feb.2004 to Dec. 2008. Correlating every intraoperative monitoring index with their follow-up results of facial nerve function 1 day and 6 months after their operations.The tendency of the two continuous monitoring techniques between nasal F wave recording and online EMG of facial muscles has also been studied in this paper. Results Among 46 cases of acoustic neurinomas, 45(97.83 %) tumors have been totally resected, and 1 (2.17 %) tumor subtotally resected,lcase (2.17 %)died after operation,and 2ases occurred the leakage of cerebrospinal fluid(CSF) which have been cured through conservative treatment. The whole anatomic protection rate of facial nerve is 97.83 %,and their functional protection rates 6 months after operation are:HB Ⅰ - Ⅱ,75.56 %;Ⅲ-Ⅳ,22.22 % and Ⅴ-Ⅵ,2.22 %.The completely accordant rate between the intraoperative findings of nasal F wave recording and online EMG is 52.17 %, partially accordant rate is 45.65 %, and totally opposite rate is 2.17 % (x2 趋势= 6.113, P ＜0.05). The intraoperative monitoring indexes in nasal muscle F wave recording are correlated well with the facial nerve function in the 6th month' s follow-up (κ=0.429, P ＜0.001).In triggered EMG monitoring after tumors being resected,the stimulus threshold ratio and maximum amplitude ratio of facial nerve between leaving brain stem part and inner acoustic porus part are also correlated well with the facial nerve function 6 months after operation(κ=0.576, P ＜0.001; κ=0.595, P ＜0.001). ConclusionNasal muscle F wa recording cooperated well with online EMG and triggered EMG intraoperatively and correlates well with the postoperative facial nerve function, so they should be routinely applied together intraoperatively.
Résumé
Objective To explore the value of F wave recording in evaluating facial nerve function and its pathological changes in the pressure-induced rat models of acoustic neurinoma. Methods 58 rats in different groups were conducted F wave recording and biotinylated dextran amine(BDA) retrograde tracing for their right facial nerve one week after establishing models. Their latencies, amplitudes and F/M rates were analyzed first. 72 hours after BDA was injected into right whisker muscle, the rats were infused with 4% polyoxymethylene, then pontines and facial nerves in the CPA cistern were obtained. Pontiues were cut into frozen sections for histochemical staining with avidin-horseradish peroxidase (HRP)-DAB and Nissl 's counterstaining, calculating the positive BDA neurons ratio(BDA+-N%)in facial nuclear. Facial nerves were cut and stained with toluidine blue for light-micrescope inspection, and/or stained for transmission electron microscope observation. Correlating F/M with BDA+-N% and the facial nerve pathological findings. Results F/M are 97.66 % and 97.48 % in normal and pseudo-operation group, respectively, when stimulus are 1.4 mA; while 77.13 %, 48.91% and 11.54 % in from small to large tumor model groups because F waves were delayed in latencies or increasinglylost (P <0.001). Similarly, BDA+-N% are 98.37 % and 97.96 % in the above two control groups, while 77.28 %, 48.28 % and 11.55 % in from small to large tumor model groups (P < 0.001). Thus F/M are positively correlated with their BDA+-N% in all groups (r =0.996,P <0.001). Facial nerve examinations under light and electron microscope show increasing pathological changes along with increasing "tumor" size. Conclusion The findings of F wave recording in facial nerve may reflect its functional status and pathological changes. Therefore, F wave detection may help electrophysiological monitoring during acoustic neurinoma resection and facial nerve function evaluation after surgery.