Transcranial Electrocortical Stimulation to Monitor the Facial Nerve Motor Function During Cerebellopontine Angle Surgery

2010 ◽  
Vol 66 (suppl_2) ◽  
pp. ons354-ons362 ◽  
Author(s):  
Marcus André Acioly ◽  
Marina Liebsch ◽  
Carlos Henrique Carvalho ◽  
Alireza Gharabaghi ◽  
Marcos Tatagiba
Keyword(s):  
Facial Nerve ◽  
Cerebellopontine Angle ◽  
Amplitude Ratio ◽  
Motor Evoked Potential ◽  
Postoperative Outcome ◽  
Abductor Pollicis Brevis ◽  
Orbicularis Oculi ◽  
Control Response ◽  
Orbicularis Oris Muscle ◽  
Facial Function

Abstract OBJECTIVE This study was conducted to investigate the success rate of using the facial motor evoked potential (FMEP) of orbicularis oculi and oris muscles for facial nerve function monitoring with use of a stepwise protocol, and its usefulness in predicting facial nerve outcome during cerebellopontine angle (CPA) surgeries. METHODS FMEPs were recorded intraoperatively from 60 patients undergoing CPA surgeries. Transcranial electrocortical stimulation (TES) was performed using corkscrew electrodes positioned at hemispheric montage (C3/C4 and CZ). The contralateral abductor pollicis brevis muscle was used as the control response. Stimulation was always applied contralaterally to the affected side using 1, 3, or 5 rectangular pulses ranging from 200 to 600 V with 50 μs of pulse duration and an interstimulus interval of 2 ms. Facial potentials were recorded from needles placed in the orbicularis oculi and oris muscles. RESULTS FMEP from the orbicularis oris and oculi muscles could be reliably monitored in 86.7% and 85% of the patients, respectively. The immediate postoperative facial function correlated significantly with the FMEP ratio in the orbicularis oculi muscle at 80% amplitude ratio (P = .037) and orbicularis oris muscle at 35% ratio (P = .000). FMEP loss was always related to postoperative facial paresis, although in different degrees. CONCLUSION FMEPs can be obtained reliably by using TES with 3 to 5 train pulses. Stable intraoperative FMEPs can predict a good postoperative outcome of facial function. However, further refinements of this technique are necessary to minimize artifacts and to make this method more reliable.

scholarly journals Impact of Motor-Evoked Potential Monitoring on Facial Nerve Outcomes after Vestibular Schwannoma Resection

2018 ◽  
Vol 128 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Kareem O. Tawfik ◽  
Zoe A. Walters ◽  
Gavriel D. Kohlberg ◽  
Noga Lipschitz ◽  
Joseph T. Breen ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Vestibular Schwannoma ◽  
Predictive Value ◽  
Evoked Potential ◽  
Amplitude Ratio ◽  
Motor Evoked Potential ◽  
Level Of Evidence ◽  
Facial Function

Objectives: Assess the utility of intraoperative transcranial facial motor-evoked potential (FMEP) monitoring in predicting and improving facial function after vestibular schwannoma (VS) resection. Study Design: Retrospective chart review. Methods: Data were obtained from 82 consecutive VS resections meeting inclusion criteria. Sixty-two cases were performed without FMEP and 20 with FMEP. Degradation of FMEP response was defined as a final-to-baseline amplitude ratio of 0.5 or less. House-Brackmann (HB) grade was assessed preoperatively, postoperatively, at follow-up assessments, and it was compared between pre- and post-FMEP cohorts. Positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity of FMEP degradation in predicting facial weakness were calculated. Results: In the pre-FMEP group, at length of follow-up (LOF) ⩾9 months, 83.9% (52/62) of patients exhibited HB 1-2 outcome. In the post-FMEP cohort, 75.0% (15/20) exhibited HB 1-2 function at LOF ⩾9 months. There was no difference in rates of HB 1-2 outcomes between groups in the immediate postoperative period ( P = .35) or at long-term follow-up ( P = 1.0). With respect to predicting immediate postoperative facial function, FMEP demonstrated high specificity (88.9%) and moderate sensitivity (54.5%). The PPV and NPV for immediate postoperative facial function were 85.7% and 61.5%, respectively. With respect to long-term (⩾9 months LOF) facial function, intraoperative FMEP was moderately sensitive (71.4%) and highly specific (84.6%); PPV was moderate (71.4%), and NPV was high (84.6%). Conclusions: Intraoperative FMEP is highly specific and moderately sensitive in predicting postoperative facial function for patients undergoing VS resection, but its use may not be associated with improved facial nerve outcomes. Level of Evidence: 4

Facial Nerve Repair in Cerebellopontine Angle Surgery

1978 ◽  
Vol 87 (6) ◽  
pp. 772-777 ◽  
Author(s):  
Derald E. Brackmann ◽  
William E. Hitselberger ◽  
Jerald V. Robinson
Keyword(s):  
Facial Nerve ◽  
Brain Stem ◽  
Cerebellopontine Angle ◽  
Nerve Repair ◽  
Nerve Graft ◽  
Tumor Removal ◽  
Stylomastoid Foramen ◽  
Substitution Procedure ◽  
The Brain ◽  
Facial Function

Facial nerve continuity was restored during cerebellopontine angle tumor removal in nine cases. The distal facial nerve was rerouted from the stylomastoid foramen into the cerebellopontine angle. Direct suture was accomplished in seven cases while two required interposition of a greater auricular nerve graft. There was excellent return of facial function in eight of the nine cases. Overall results are superior to nerve substitution techniques. The facial nerve should be inspected for continuity following tumor removal. If one is not certain the nerve is intact, the proximal facial stump should be identified at the brain stem and facial nerve continuity reestablished. A nerve substitution procedure should be resorted to at a later time only when the proximal facial stump is not identifiable.

Electroneurography: Preoperative Facial Nerve Assessment for Tumors of the Temporal Bone

1987 ◽  
Vol 97 (3) ◽  
pp. 257-261 ◽  
Author(s):  
Jack M. Kartush ◽  
John K. Niparko ◽  
Malcolm D. Graham ◽  
John L. Kemink
Keyword(s):  
Facial Nerve ◽  
Motor Unit ◽  
Temporal Bone ◽  
Acoustic Neuroma ◽  
Tumor Size ◽  
Cerebellopontine Angle ◽  
Nerve Degeneration ◽  
Tumor Surgery ◽  
Clinically Normal ◽  
Facial Function

Tumors of the temporal bone and cerebellopontine angle may be associated with subclinical facial nerve degeneration, despite clinically normal facial function. To determine if preoperative neurophysiologic testing might predict postoperative facial function after tumor surgery, preoperative facial electroneurography (ENoG) was performed in 82 patients with confirmed tumors of the temporal bone and cerebellopontine angle. In patients with acoustic neuroma, preoperative ENoG amplitude reduction varied directly with tumor size. In addition, a statistically significant association between impaired postoperative facial function and acoustic neuroma size greater than 2.5 cm was found. However, preoperative ENoG amplitude reduction did not accurately predict postoperative facial function. These findings suggest that factors, such as the type and size of tumor, the microanatomic relationship between the facial nerve and the neoplasm, and/or desynchronization of the evoked motor-unit volley, may effect results obtained with ENoG in this setting.

Cerebellopontine Angle Surgery Assisted by Continuous Mapping of the Facial Nerve Via the Ultrasonic Aspirator

2020 ◽  
Author(s):  
Marco Cenzato ◽  
Roberto Stefini ◽  
Francesco Zenga ◽  
Maurizio Piparo ◽  
Alberto Debernardi ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Facial Nerve ◽  
Cerebellopontine Angle ◽  
Continuous Mapping ◽  
Cost Effective ◽  
Current Intensity ◽  
Vestibular Schwannomas ◽  
Constant Current ◽  
Surgical Workflow ◽  
Ultrasonic Aspirator

Abstract Background Cerebellopontine angle (CPA) surgery carries the risk of lesioning the facial nerve. The goal of preserving the integrity of the facial nerve is usually pursued with intermittent electrical stimulation using a handheld probe that is alternated with the resection. We report our experience with continuous electrical stimulation delivered via the ultrasonic aspirator (UA) used for the resection of a series of vestibular schwannomas. Methods A total of 17 patients with vestibular schwannomas, operated on between 2010 and 2018, were included in this study. A constant-current stimulator was coupled to the UA used for the resection, delivering square-wave pulses throughout the resection. The muscle responses from upper and lower face muscles triggered by the electrical stimulation were displayed continuously on multichannel neurophysiologic equipment. The careful titration of the electrical stimulation delivered through the UA while tapering the current intensity with the progression of the resection was used as the main strategy. Results All operations were performed successfully, and facial nerve conduction was maintained in all patients except one, in whom a permanent lesion of the facial nerve followed a miscommunication to the neurosurgeon. Conclusion The coupling of the electrical stimulation to the UA provided the neurosurgeon with an efficient and cost-effective tool and allowed a safe resection. Positive responses were obtained from the facial muscles with low current intensity (lowest intensity: 0.1 mA). The availability of a resection tool paired with a stimulator allowed the surgeon to improve the surgical workflow because fewer interruptions were necessary to stimulate the facial nerve via a handheld probe.

Intraoperative facial motor evoked potential monitoring for pontine cavernous malformation resection

2020 ◽  
Vol 132 (1) ◽  
pp. 265-271
Author(s):  
Ridzky Firmansyah Hardian ◽  
Tetsuya Goto ◽  
Yu Fujii ◽  
Kohei Kanaya ◽  
Tetsuyoshi Horiuchi ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Cavernous Malformation ◽  
Motor Evoked Potentials ◽  
Motor Evoked Potential ◽  
Warning Signs ◽  
Constant Current ◽  
Karnofsky Performance Scale ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Cavernous Malformations

OBJECTIVEThe aim of this study was to predict postoperative facial nerve function during pontine cavernous malformation surgery by monitoring facial motor evoked potentials (FMEPs).METHODSFrom 2008 to 2017, 10 patients with pontine cavernous malformations underwent total resection via the trans–fourth ventricle floor approach with FMEP monitoring. House-Brackmann grades and Karnofsky Performance Scale (KPS) scores were obtained pre- and postoperatively. The surgeries were performed using one of 2 safe entry zones into the brainstem: the suprafacial triangle and infrafacial triangle approaches. Six patients underwent the suprafacial triangle approach, and 4 patients underwent the infrafacial triangle approach. A cranial peg screw electrode was used to deliver electrical stimulation for FMEP by a train of 4 or 5 pulse anodal constant current stimulation. FMEP was recorded from needle electrodes on the ipsilateral facial muscles and monitored throughout surgery by using a threshold-level stimulation method.RESULTSFMEPs were recorded and analyzed in 8 patients; they were not recorded in 2 patients who had severe preoperative facial palsy and underwent an infrafacial triangle approach. Warning signs appeared in all patients who underwent the suprafacial triangle approach. However, after temporarily stopping the procedures, FMEP findings during surgery showed recovery of the thresholds. FMEPs in patients who underwent the infrafacial triangle approach were stable during the surgery. House-Brackmann grades were unchanged postoperatively in all patients. Postoperative KPS scores improved in 3 patients, decreased in 1, and remained the same in 6 patients.CONCLUSIONSFMEPs can be used to monitor facial nerve function during surgery for pontine cavernous malformations, especially when the suprafacial triangle approach is performed.

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