Intraoperative cranial nerve monitoring

Harper, C. Michel

doi:10.1002/mus.10506

Cited by 59 publications

(44 citation statements)

References 102 publications

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“…Neurotonic discharges do not necessarily indicate nerve damage and their absence do not exclude nerve injury. Controlled studies are not available to determine whether or not cranial nerve monitoring during MCF surgery reduces the risk of postoperative ophthalmoplegia, 22 although there are controlled data to suggest that monitoring reduces the risk of cranial nerve injury in selected situations (e.g., facial nerve during acoustic schwannoma resection, and auditory nerve during acoustic schwannoma and microvascular decompression for hemifacial spasm). [23][24][25] …”

Section: Discussionmentioning

confidence: 99%

Transzygomatic Approach with Intraoperative Neuromonitoring for Resection of Middle Cranial Fossa Tumors

et al. 2011

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Access to the floor of the middle cranial fossa (MCF) is often required when performing cranial base approaches to expose various lesions of the petrous apex, petroclival junction, internal auditory canal, and posterior cavernous sinus. In many patients with these lesions, a temporal craniotomy is sufficient to reach the floor of the MCF. However, the caudal limit of a simple temporal craniotomy is the zygomatic arch, which can present an obstacle in accessing the MCF in some individuals. Several authors have advocated mobilizing the zygomatic arch by performing a simple zygomatic osteotomy or using extended frontotemporo-orbitozygomatic approaches to reach low-lying lesions. [1][2][3] Intraoperative neuromonitoring (IOM) is one of the methods in which modern neurosurgery can improve surgical results while reducing morbidity. Motor-evoked potentials (MEPs) obtained by transcranial electrocortical stimulation is routinely used to monitor major motor pathways intraoperatively during several neurosurgical procedures. 4-6 Monitoring of oculomotor, trochlear, trigeminal, and facial nerve function is usually performed using free-running electromyography (EMG) or by direct stimulation of each cranial nerve. 7-9 Keywords ► middle fossa approach ► skull base surgery ► motor-evoked potentials ► intraoperative monitoring ► neurophysiology AbstractThe authors reviewed the surgical experience and operative technique in a series of 11 patients with middle fossa tumors who underwent surgery using the transzygomatic approach and intraoperative neuromonitoring (IOM) at a single institution. This approach was applied to trigeminal schwannomas (n ¼ 3), cavernous angiomas (n ¼ 3), sphenoid wing meningiomas (n ¼ 3), a petroclival meningioma (n ¼ 1), and a hemangiopericytoma (n ¼ 1). An osteotomy of the zygoma, a low-positioned frontotemporal craniotomy, removal of the remaining squamous temporal bone, and extradural drilling of the sphenoid wing made a flat trajectory to the skull base. Total resection was achieved in 9 of 11 patients. Significant motor pathway damage can be avoided using a change in motor-evoked potentials as an early warning sign. Four patients experienced cranial nerve palsies postoperatively, even though free-running electromyography of cranial nerves showed normal responses during the surgical procedure. A simple transzygomatic approach provides a wide surgical corridor for accessing the cavernous sinus, petrous apex, and subtemporal regions. Knowledge of the middle fossa structures is essential for anatomic orientation and avoiding injuries to neurovascular structures, although a neuronavigation system and IOM helps orient neurosurgeons.

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Section: Discussionmentioning

confidence: 99%

Transzygomatic Approach with Intraoperative Neuromonitoring for Resection of Middle Cranial Fossa Tumors

et al. 2011

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“…In addition, particular changes in LSR and BAEP monitoring can be used to predict postoperative function [27]. The term ‘LSR’ is used to describe an electrophysiological phenomenon, which is a result of ephaptic transmission between facial axons at the site of vascular compression or hyperexcitability of the pontine facial nucleus [17]. Consequently, LSR is only a valuable factor for adequate nerve decompression and aids in predicting clinical outcomes [17].…”

Section: Discussionmentioning

confidence: 99%

“…Although most cases of postoperative facial weakness are transient and have ambiguous causes, permanent facial weakness resulting from intraoperative damage to the facial nerve may develop [15]. During MVD for HFS, intraoperative facial electromyography (EMG) and brainstem auditory evoked potential (BAEP) are generally needed for several reasons including reduction of nerve damage and assessment of the lateral spread response (LSR) as a prognostic indicator of treatment outcome [16,17]. However, to our knowledge, intraoperative facial EMG and BAEP in patients with delayed facial weakness after MVD have not been studied.…”

Section: Introductionmentioning

confidence: 99%

Intraoperative Facial Electromyography and Brainstem Auditory Evoked Potential Findings in Microvascular Decompression for Hemifacial Spasm: Correlation with Postoperative Delayed Facial Palsy

Kim

Park

Ryu³

et al. 2012

Stereotact Funct Neurosurg

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Background: Delayed facial palsy (DFP) after microvascular decompression (MVD) in patients with hemifacial spasm (HFS) is not uncommon, but the cause remains unknown. Objectives: To assess whether intraoperative electromyography (EMG) and brainstem auditory evoked potential (BAEP) can predict DFP after MVD. Methods: Between September 2009 and February 2011 we examined 86 patients, 9 of whom (10.4%) developed DFP after MVD on the same side. All patients underwent MVD and were followed-up for a median period of 13 months (range 6–22). We retrospectively examined intraoperative facial EMG and BAEP findings using our MVD patients’ registry. We excluded secondary HFS and immediate postoperative facial palsy after MVD in this study. We assessed the prevalence and clinical characteristics of DFP and compared EMG and BAEP findings between DFP and non-DFP groups. Results: All patients recovered completely, with a mean time to recovery of 37.8 days (range 22–57). There were no significant differences between DFP and non-DFP patients in terms of the amplitude and latency of intraoperative EMG and BAEP. Conclusion: The usefulness of intraoperative facial EMG and BAEP is limited and cannot predict DFP after MVD for HFS. We speculate that DFP after MVD is not associated with permanent nerve damage according to the EMG findings.

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“…However, if a nerve is transected abruptly, there will be only brief or no EMG activity. 12 We also observed that free-run EMG has a lower sensitivity for detecting cranial deficits during EES. Free-run EMG activity is observed secondary to the activation of a CN due to manipulation during tumor dissection, bipolar use, as well as other maneuvers during the surgery.…”

Section: Emg Monitoringmentioning

confidence: 56%

“…Based on this study and published suggestions, CN free-run EMG and triggered EMG monitoring, especially during staged procedures and for recurrent tumors, might be valuable for reducing morbidity by identifying the nerve during tumor dissection. 11,12 Communicating free-run EMG activity to the surgeon plays a key role in complex decision making during tumor dissection. The predictability of the increased risk of clinically significant injury by free-run EMG and the lack of deficits in those few cases with documented triggered EMG strongly support the role of these modalities during EES.…”

Section: Emg Monitoringmentioning

confidence: 99%

Intraoperative neurophysiological monitoring during endoscopic endonasal surgery for pediatric skull base tumors

Elangovan¹,

Singh²,

Gardner³

et al. 2016

PED

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OBJECT The aim of this study was to evaluate the value of intraoperative neurophysiological monitoring (IONM) using electromyography (EMG), brainstem auditory evoked potentials (BAEPs), and somatosensory evoked potentials (SSEPs) to predict and/or prevent postoperative neurological deficits in pediatric patients undergoing endoscopic endonasal surgery (EES) for skull base tumors. METHODS All consecutive pediatric patients with skull base tumors who underwent EES with at least 1 modality of IONM (BAEP, SSEP, and/or EMG) at our institution between 1999 and 2013 were retrospectively reviewed. Staged procedures and repeat procedures were identified and analyzed separately. To evaluate the diagnostic accuracy of significant free-run EMG activity, the prevalence of cranial nerve (CN) deficits and the sensitivity, specificity, and positive and negative predictive values were calculated. RESULTS A total of 129 patients underwent 159 procedures; 6 patients had a total of 9 CN deficits. The incidences of CN deficits based on the total number of nerves monitored in the groups with and without significant free-run EMG activity were 9% and 1.5%, respectively. The incidences of CN deficits in the groups with 1 staged and more than 1 staged EES were 1.5% and 29%, respectively. The sensitivity, specificity, and negative predictive values (with 95% confidence intervals) of significant EMG to detect CN deficits in repeat procedures were 0.55 (0.22–0.84), 0.86 (0.79–0.9), and 0.97 (0.92–0.99), respectively. Two patients had significant changes in their BAEPs that were reversible with an increase in mean arterial pressure. CONCLUSIONS IONM can be applied effectively and reliably during EES in children. EMG monitoring is specific for detecting CN deficits and can be an effective guide for dissecting these procedures. Triggered EMG should be elicited intraoperatively to check the integrity of the CNs during and after tumor resection. Given the anatomical complexity of pediatric EES and the unique challenges encountered, multimodal IONM can be a valuable adjunct to these procedures.

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Intraoperative cranial nerve monitoring

Cited by 59 publications

References 102 publications

Transzygomatic Approach with Intraoperative Neuromonitoring for Resection of Middle Cranial Fossa Tumors

Transzygomatic Approach with Intraoperative Neuromonitoring for Resection of Middle Cranial Fossa Tumors

Intraoperative Facial Electromyography and Brainstem Auditory Evoked Potential Findings in Microvascular Decompression for Hemifacial Spasm: Correlation with Postoperative Delayed Facial Palsy

Intraoperative neurophysiological monitoring during endoscopic endonasal surgery for pediatric skull base tumors

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