Spontaneous and evoked facial muscle electromyogram in monitoring nervous function in acoustic neuroma surgery and nervous prognosis: A character analysis in 120 cases / 中国组织工程研究

ABSTRACT

BACKGROUND: The anatomical position of facial nerve is often abnormal because of the acoustical neuroma growth, so sometimes, the facial nerve injury is inevitable in the surgery treatment for acoustic neuroma.OBJECTIVE: To investigate the technology, veracity and practicality as well as the relationship between intraoperative monitorning and prognosis of facial nerve, and the clinical experiment was summed up of facial nerve function monitoring in 120 cases of acoustic neuroma surgery.DESIGN: Self-control observation.SETTING: Department of Neurosurgery, General Hospital of Chinese PLA.PARTICIPANTS: Totally 120 patients with acoustic neuroma who received treatment in the Department of Neurosurgery, General Hospital of Chinese PLA from May 1996 to February 2000 were recruited. Among them, 3 cases suffered from small-type acoustic neuroma (＜ 2 cm in diameter), 9 cases from middle-type acoustic neuroma (＞ 2 cm in diameter) and 108 from large-type acoustic neuroma (＞ 3 cm in diameter), including 1 case of bilateral acoustic neuroma and 1 cases of recrudescent acoustic neuroma; Suboccipital retromastoid approach was used in 119 cases and transretrolabyrinthine approach in 1 case.METHODS: American Viking-Ⅳ type monitor was used to monitor facial nervous function. When facial nervous function was monitored, recording electrode was put on orbicular muscle of eye, orbicular muscle of mouth or quadrate muscle of upper lip. When trigeminal motor branch was monitored, recording electrode was put on masseter muscle; When accessory nerve was monitored, recording electrode was put on trapezius muscle.Measurement of evoked auditory brainstem potential recording electrode was positive electrode and was put at the midline in the frontal region (electroencephalogram 10-20 classification system). The recorded waveshape presented upward deflection. Reference electrode A1 or A2 and ground electrode were put in the midline of frontal pole (relevant to root of nose); Recording electrodes were all needle electrodes and were fixed with adhesive tape. Common stimulus intensity was 80 to 90 nHL, and 40 nHL noise was used in contralateral ear. Facial nerve was reserved following intraoperative monitoring. CT (enhancement scanning was necessary) or MRI was rechecked after operation to investigate the cutting degree of tumor; Facial nerve function was evaluated by H-B scoring (at 2 weeks, or 6 to 9 months following operation).MAIN OUTCOME MEASURES: Facial nerve function by H-B scoring before and after acoustic neuroma surgery.RESULTS: Totally 120 patients were enrolled, and no one dropped out.① Facial nerve anatomy was reserved in 117 cases; One case was failure to reserve facial nerve anatomy because pinnate facial nerve lay behind of acoustic neuroma, and electrical stimulation was not given at the beginning of neuroma resecting, then he received anastomosis of hypoglossal and facial nerve. Nerve of 2 cases was pulled and broken carelessly, and its two stumps were long enough that end-to-end anastomosis of facial nerve was performed with 7-0 absorbable suture following trimming. H-B score was Ⅳ to Ⅴ in the 6th month after surgery. ②Grade Ⅰ of facial nervous function at postoperative 2 weeks was found in 10 cases, grade Ⅱ in 57 cases,grade Ⅲ in 44 eases, grade Ⅳ in 4 cases, grade Ⅴ in 2 cases and gradeⅥ in 3 cases. ③Grade Ⅰ of facial nervous function at postoperative 9 weeks was found in 94 cases, grade Ⅱ in 18 cases, grade Ⅲ in 4 cases,grade Ⅳ in 1 case and grade Ⅵ in 2 cases.CONCLUSION: Spontaneous and evoked facial muscle electromyogram may be helpful to make sure the facial nervous position exactly and estimate the prognosis of facial nerve.