Intraoperative Facial Monitoring Research Articles

Stratifying the risk of facial nerve palsy after benign parotid surgery

Post-operative facial palsy is the most important potential complication of parotid surgery for benign lesions. The published prevalence of facial weakness is up to 57 per cent for temporary weakness and up to 7 per cent for permanent weakness. We aimed to identify potential risk factors for post-operative facial palsy. One hundred and fifty patients who had undergone parotid surgery for benign disease were retrospectively reviewed. Tumour factors (size, location and histopathology), patient factors (age and sex) and operative factors (operation, surgeon grade, surgeon specialty and use of intra-operative facial nerve monitoring) were all analysed for significant associations with post-operative facial palsy. The overall incidence of facial palsy was 26.7 per cent for temporary weakness and 2.6 per cent for permanent weakness. The associations between facial palsy and all the above factors were analysed using Pearson's chi-square test and found to be non-significant. These outcomes compare favourably with the literature. No significant risk factors were identified, suggesting that atraumatic, meticulous surgical technique is still the most important factor affecting post-operative facial palsy.

The utility of facial nerve amplitude and latency ratios in predicting postoperative facial nerve function after vestibular schwannoma surgery.

Despite advances in vestibular schwannoma (VS) surgery and intraoperative electrophysiological monitoring, immediate and delayed facial nerve outcomes are difficult to accurately predict consistently. To determine the utility of proximal to distal facial nerve amplitude and latency ratios in predicting the long-term postoperative facial nerve function in patients undergoing excision of VS. One hundred consecutive patients undergoing surgery for VS with intraoperative facial nerve monitoring were included. Clinical, radiological, electrophysiological, and postoperative outcome data were prospectively entered into a database. Other parameters such as brainstem distance, size of the porus acousticus, and facial nerve length were also analyzed. Of the 100 patients, 53 were women. The mean age was 42.5 ± 14.1 years (range, 14-71 years) and the average tumor size was 4.1 ± 0.8 cm (range, 2.4-6.5 cm). Total excision was done in 89% of patients. Intraoperatively, the facial nerve was anatomically preserved in 86 patients, but electrophysiological responses were obtained from the root entry zone (REZ) in only 77 patients at the end of surgery, 75% of which had good facial function at long-term follow-up. In nine patients where no responses were obtained but the facial nerve was anatomically intact, 50% had good facial function at long-term follow-up. Proximal and distal amplitude and latency ratios, size or consistency of the tumor, brainstem distance, size of the porus acousticus, and length of the facial nerve were not useful in predicting long-term functional outcome. While a positive response to facial nerve stimulation at the end of VS surgery is a good predictor of long-term postoperative function, the absence of responses in an anatomically intact nerve does not preclude good function in the long term. Proximal to-distal amplitude and latency ratios did not correlate with the final facial function.

92. The role of blink reflex in intraoperative neurophysiological facial nerve monitoring during cerebellopontine angle (CPA) surgery

Intraoperative neurophysiological monitoring of Facial nerve (FN) has become an integral part of CPA surgery, mainly to preserve nerves functional integrity. Deletis et al. (2009) described a technique to elicit the blink reflex (BR) during anaesthesia. Our aim was to investigate technical aspects, success rate of BR during IOM, its reliability and usefulness in predicting FN outcome. 19 pts affected by APC tumours (neurinoma, meningioma and brainstem astrocytoma) and hemifacial spasm were studied. Free run EMG, FN cMAP and BR were recorded during surgery. BR was recordable in 90%. There was a good correlation between BR stability and positive outcome. The patient who showed BR decrement or disappearance had a severe FN deficit at postIOM evaluation. BR is a method of simple execution that does not interfere with neurosurgeon activity. It can be added to other classical techniques to improve IOM reliability.

Surgery for traumatic facial nerve paralysis: Does intraoperative monitoring have a role?

The use of intraoperative facial nerve (FN) monitoring during surgical decompression of the FN is underscored because surgery is indicated when the FN shows more than 90 % axonal degeneration. The present study proposes including intraoperative monitoring to facilitate decision taking and provide prognostication with more accuracy. This prospective study was conducted on ten patients presenting with complete FN paralysis due to temporal bone fracture. They were referred after variable time intervals for FN exploration and decompression. Intraoperative supramaximal electric stimulation (2-3 mA) of the FN was attempted in all patients both proximal and distal to the site of injury. Postoperative FN function was assessed using House-Brackmann (HB) scale. All patients had follow-up period ranging from 7 to 42 months. Three different patterns of neurophysiological responses were characterized. Responses were recorded proximal and distal to the lesion in five patients (pattern 1); only distal to the lesion in two patients (pattern 2); and neither proximal nor distal to the lesion in three patients (pattern 3). Sporadic, mechanically elicited EMG activity was recorded in eight out of ten patients. Patients with pattern 1 had favorable prognosis with postoperative function ranging between grade I and III. Pattern 3 patients showing no mechanically elicited activity had poor prognosis. Intraoperative monitoring affects decision taking during surgery for traumatic FN paralysis and provides prognostication with sufficient accuracy. The detection of mechanically elicited EMG activity is an additional sign predicting favorable outcome. However, absence of responses did not alter surgeon decision when the nerve was found evidently intact.

The Role of Intraoperative Facial Nerve Monitoring during Parotidectomy for Benign Parotid Gland Tumors

Objectives: 1) Compare outcomes of parotidectomy with and without electrophysiologist-assisted intraoperative nerve monitoring (IOM) for the treatment of benign parotid gland tumors. 2) Recognize potential benefits of IOM in parotidectomy. Methods: Retrospective case control of 151 consecutive patients undergoing parotidectomy for treatment of benign tumors between March 2006 and December 2011 at Weill Cornell Medical College. Interventions included parotidectomy and IOM. Outcome measures included complications from intervention(s). Results: Sixty-four percent of patients were female, and the median age at surgery was 57 years (range 17 - 86 years). The majority of patients (70%) had pleomorphic adenomas. One surgeon performed all 81 parotidectomies with IOM (54%), while another surgeon performed the remainder without IOM (46%). IOM use depended on the attending surgeon and was not due to any other factor. Superficial parotidectomies comprised 81% and 70% of surgeries performed with and without IOM, respectively. Temporary facial nerve dysfunction occurred in 10.6% of patients. No statistically significant difference was seen in temporary facial nerve paralysis rates post-operatively between groups with IOM (9.9%) and those without (11.4%) ( P = 0.76). In cases with IOM, electrical mapping and presence of transient nerve irritation did not influence the rate of complications ( P = 0.19). Conclusions: Use of IOM does not appear to impact the rate of facial paralysis post-parotidectomy for benign parotid gland tumors. However, IOM may be beneficial in aiding the surgeon in difficult cases, to preserve smaller branches, or when the tumor lies particularly close to the facial nerve.

Reversal of moderate and intense neuromuscular block induced by rocuronium with low doses of sugammadex for intraoperative facial nerve monitoring

We report two cases in which moderate and intense rocuronium-induced neuromuscular block was reversed intraoperatively with low sugammadex doses in order to facilitate electromyographic evaluation of facial nerve function during surgery of the parotid gland and the middle ear. Acceleromyography was used to assess reversal of neuromuscular block before starting electromyography monitoring. Rocuronium-induced neuromuscular block was reversed with sugammadex 0.22mgkg−1 when the TOF ratio was 0.14 in the first patient, and with sugammadex 2mgkg−1 during intense block (PTC 0) in the second patient. In each case, appropriate neuromuscular function (TOF ratio≥0.9) was established soon after sugammadex administration, and electromyographic evaluation of facial nerve was successfully conducted. The use of rocuronium and sugammadex, coupled with objective neuromuscular monitoring with acceleromyography, assured complete restoration of neuromuscular function and created the optimal conditions for the surgical team.

Supramaximal stimulation during intraoperative facial nerve monitoring as a simple parameter to predict early functional outcome after parotidectomy

Conclusion: A supramaximal stimulation at 2 mA during intraoperative electromyographic (EMG) facial nerve monitoring appears to be a simple and effective parameter to predict immediate postoperative injury. Objectives: To assess the role of systematic intraoperative facial nerve monitoring in predicting the early functional outcomes obtained after parotidectomy. Methods: Data were collected from patients who underwent parotidectomy. Intraoperative EMG monitoring of the facial nerve was performed by registering two parameters, event intensity (>100 μV) and amplitude of response after a supramaximal stimulation at 2 mA, at the beginning and end of gland removal. Early postoperative clinical functional facial nerve disorder was assessed at day 2. Results: Overall, 50 patients were included and an early facial dysfunction was detected in 27 cases (54%). The maximal response amplitude after supramaximal stimulation at the trunk of the facial nerve was higher in patients with normal facial function compared with those with poor outcomes at the end of surgery (p < 0.01). The postdissection to predissection ratios of maximal response amplitude, but not the stimulation thresholds, were indicative of a nerve conduction block and were significantly lower in the patient group with a poor outcome compared with the group with a normal facial outcome (p < 0.02).

Single‐Stage Excision of Localized Head and Neck Venous Malformations Using Preoperative Glue Embolization

Describe single-stage removal of head and neck venous malformations using percutaneous embolization with n-butyl cyanoacrylate (n-BCA) glue prior to surgical resection. Case series with chart review. Tertiary-care pediatric hospital. A total of 169 venous malformations were identified between 2000 and 2012, and 102 (60.1%) were in the head and neck. Thirty-five of 102 (34.3%) were observed, 56 of 102 (54.9%) had invasive therapy, and 11 of 102 (10.8%) underwent n-BCA embolization and surgery ("GES procedure"). The median age of the glue embolization and surgery cohort was 14 years (range, 6-19), and 7 of 11 (63.6%) were female. Treated venous malformations involved the oral cavity/tongue (4/11; 36.4%) and parotid/face (7/11; 63.6%). During facial lesion excision, intraoperative facial nerve monitoring was used. All surgical sites (11/11) were closed primarily. No patient in this cohort had any posttreatment nerve deficits, dysarthria, and dysphagia or lesion persistence. Localized venous malformations can be treated with preoperative percutaneous embolization with n-BCA glue followed by surgical excision. This technique, with selective motor nerve monitoring, appears safe and allows for complete venous malformation removal with limited nerve dissection, to allow maximal tissue and functional preservation.

The value of intraoperative facial nerve monitoring and preoperative FNAC in superficial parotidectomy: facial nerve morbidity outcome

AbstractIntraoperative use of nerve integrity monitors has been advocated to enhance nerve identification. We evaluate the impact of two controversial procedures used in surgical management of parotid tumors on postoperative facial nerve morbidity in University Kebangsaan Medical Centre, Malaysia: fine needle aspiration cytology and continuous facial monitoring using a nerve integrity monitor (NIM). This is a retrospective study on 15 cases of superficial parotidectomy performed during a 2-year period (2008–2010). In our opinion, using an NIM is optional for parotid tumors of the superficial lobe; however, performing preoperative fine needle aspiration cytology and using an NIM may help operative planning and improve medical education in a teaching hospital.

Use of supramaximal stimulation to predict facial nerve outcomes following vestibular schwannoma microsurgery: results from a decade of experience

The goal of vestibular schwannoma surgery is tumor removal and preservation of neural function. Intraoperative facial nerve (FN) monitoring has emerged as the standard of care, but its role in predicting long-term facial function remains a matter of debate. The present report seeks to describe and critically assess the value of applying current at supramaximal levels in an effort to identify patients destined for permanent facial paralysis. Over more than a decade, the protocol for stimulating and assessing the FN during vestibular schwannoma surgery at the authors' institution has consisted of applying pulsed constant-current stimulation at supramaximal levels proximally and distally following tumor resection to generate an amplitude ratio, which subtracted from 100% yields the degree to which the functional integrity of the FN "dropped off" intraoperatively. These data were prospectively collected and additional variables that might impact postoperative FN function were retrospectively reviewed from the medical record. Only patients with anatomically intact FNs and > 12 months of follow-up data were analyzed. There were 267 patients available for review. The average posterior fossa tumor diameter was 24 mm and the rate of long-term good (House-Brackmann Grade I-II) FN function was 84%. Univariate logistic regression analysis revealed that prior treatment, neurofibromatosis Type 2 status, tumor size, cerebellopontine angle extension, subjectively thinned FN at the time of operation, minimal stimulation threshold, percent dropoff by supramaximal stimulation (SMS), and postoperative FN function all correlated statistically (p < 0.05) with long-term FN function. When evaluating patients with significant FN weakness at the time of hospital discharge, only the percent dropoff by SMS remained a significant predictor of long-term FN function. However, the positive predictive value of SMS for long-term weakness is low, at 46%. In a large cohort of patients, the authors found that interrogating intraoperative FN function with SMS is safe and technically simple. It is useful for predicting which patients will ultimately have good facial function, but is very limited in identifying patients destined for long-term facial weakness. This test may prove helpful in the future in tailoring less than gross-total tumor removal to limit postoperative facial weakness.

Subtemporal Epidural and Interdural Approach for the Greater Petrosal Nerve Schwannomas

Schwannomas arising from the greater petrosal nerve (GPN) are exceedingly rare: only 10 such cases have been reported in the English literature. We report on 4 cases of GPN schwannomas and discuss the surgical approach for their removal. 4 patients with GPN schwannomas underwent surgery at Keio University Hospital We present the pre- and postoperative clinical findings and describe the structures around the GPN schwannomas as observed during the surgery. Histological sections were performed around the GPN using Masson's trichrome stain to elucidate the membrane structures. Three patients presented with xerophthalmia, and one with facial palsy, hearing disturbance, and generalized convulsions. Contrast-enhanced magnetic resonance (MR) images revealed tumors in the temporal lobe. Bone-window computed tomography (CT) showed erosion of the anterior petrous apex. During the operation, the temporal lobe was retracted epidurally. The tumors were visible inside the interdural space and covered with the epineurium. In three cases, the tumors were completely removed, and in one case the tumor was subtotally removed with intraoperative facial monitoring. In the histological sections, we confirmed that the GPN ran within the interdural space.

Importance of Low Amplitude Positive Facial Nerve Stimulation Following CP Angle Tumor Surgery

Introduction: Preservation of facial nerve function is crucial to a successful CP angle tumor resection. Intraoperative facial nerve monitoring is a routine component of CP angle surgery. We sought to correlate short-term and long-term facial nerve function with respect to the minimum amplitude of stimulation required to obtain facial nerve identification at the conclusion of tumor resection.

New Insulated Dissectors for Intraoperative Facial Nerve Monitoring in Oto-neurosurgery

New Insulated Dissectors for Intraoperative Facial Nerve Monitoring in Oto-neurosurgery

P12.14 Intraoperative neurophysiological facial nerve monitoring during cerebellopontine angle (CPA) surgeries: the role of blink reflex

P12.14 Intraoperative neurophysiological facial nerve monitoring during cerebellopontine angle (CPA) surgeries: the role of blink reflex

Thirteen years’ experience with superficial partial parotidectomy as treatment for benign parotid tumours

IntroductionMost authors agree that surgery is the treatment of choice for benign tumours of the parotid gland. However, the best surgical technique and the extent of surgery remain controversial. This study attempts to establish whether the implementation of a partial superficial parotidectomy (PSP) is appropriate for the treatment of benign parotid gland tumours. Material and methodsWe selected 63 patients with benign parotid gland surgery, of whom 43 had a pleomorphic adenoma and 20, a Warthin tumour. Of this group of 63 patients, 6 could not be included. We consequently studied 57 patients, 41 of them diagnosed as pleomorphic adenoma and 16, as Warthin tumours. In all of them, a PSP was performed without intraoperative monitoring of the facial nerve. ResultsTransient facial nerve paralysis, 14 patients (24.5%). Ten cases were resolved within the first month after surgery and 4 before the third month, after indicating facial physiotherapy. One patient (1.7%) had a permanent difficulty in keeping one side of the lower lip aligned under pressure-mobility, without altering commissure mobility. None of the patients studied had a recurrence (control, 3–13 years). ConclusionsAlthough PSP is a technique with a few complications, it has a recurrence rate comparable to or lower than other techniques used for the treatment of pleomorphic adenomas or Warthin parotid tumours. Intraoperative facial nerve monitoring can be helpful during surgery. The lack of monitoring would not be considered a contraindication for surgery.

Retraction: Systematized Intraoperative Facial Nerve Monitoring in Middle Ear and Mastoid Surgery; 'Surgical Dehiscence' and 'Electrical Dehiscence'

The following original article from Korean Journal of Otolaryngology-Head and Neck Surgery, “Systematized Intraoperative Facial Nerve Monitoring in Middle Ear and Mastoid Surgery; ‘Surgical Dehiscence’ and ‘Electrical Dehiscence” by Yun-Hoon Choung, published on March 2006 has been withdrawn from publication by agreement among the authors, the journal Editor, Sung Won Chae, and the publisher ML communications Co., Ltd. The retraction has been agreed due to substantial overlap of the content of this article with previously published one. The author and the Journal apologize to readers.

Clinical Usefulness of a Special Mosquito Clamp for Intraoperative Facial Nerve Monitoring for Tumors of the Parotid Gland and Parapharyngeal Space

Surgery of parotid gland and parapharyngeal tumors is one of the most common operations and identification and functional preservation of the facial nerve are considered to be important procedure in these operations. We developed a special mosquito clamp for facial nerve monitoring during dissection. This clamp is connected to a Nerve Integrity Monitoring System (NIM-Response® 2.0, Medtronic USA). By using this clamp, we can always monitor the facial nerve function during tissue dissection without the stimulating probe. We report herein on the clinical usefulness of the monitoring mosquito clamp and NIM system to preserve the facial nerve function in 10 cases of parotid gland and parapharyngeal tumor. Facial nerve function was well preserved in all cases, thus this monitoring clamp and NIM system are very useful for the preservation of facial nerve function during parotid and parapharyngeal tumor surgery.

New Development in Intraoperative Video Monitoring of Facial Nerve

The present study proposes an evolution of an intraoperative video-based facial nerve monitoring system for otologic and otoneurosurgical procedures in comparison with classical electromyographic (EMG) monitoring method. Single-subject design study. Tertiary referral center, university clinic. Fifteen patients undergoing a translabyrinthine approach for removal of 2 cm or less acoustic neuroma. Intraoperative monitoring during acoustic neuroma removal. Measurement of mouth angle displacement and EMG peak amplitude at different stimulation intensities were measured and compared to evaluate the validity and reliability of the proposed new system. The electrophysiologic method has been shown to be slightly more sensitive, although it shows limitations especially in terms of electrical artifacts during cauterization, totally masking the EMG monitoring. The present version of video system can be considered as valid and reliable as EMG; its main advantages are the absence of electrical artifacts, less invasivity, and much less cost.

Trece años de experiencia en parotidectomía parcial superficial como tratamiento de neoformaciones benignas parotideas

Introduction Most authors agree that surgery is the treatment of choice for benign tumours of the parotid gland. However, the best surgical technique and the extent of surgery remain controversial. This study attempts to establish whether the implementation of a partial superficial parotidectomy (PSP) is appropriate for the treatment of benign parotid gland tumours. Material and methods We selected 63 patients with benign parotid gland surgery, of whom 43 had a pleomorphic adenoma and 20, a Warthin tumour. Of this group of 63 patients, 6 could not be included. We consequently studied 57 patients, 41 of them diagnosed as pleomorphic adenoma and 16, as Warthin tumours. In all of them, a PSP was performed without intraoperative monitoring of the facial nerve. Results Transient facial nerve paralysis, 14 patients (24.5%). Ten cases were resolved within the first month after surgery and 4 before the third month, after indicating facial physiotherapy. One patient (1.7%) had a permanent difficulty in keeping one side of the lower lip aligned under pressure-mobility, without altering commissure mobility. None of the patients studied had a recurrence (control, 3-13 years). Conclusions Although PSP is a technique with a few complications, it has a recurrence rate comparable to or lower than other techniques used for the treatment of pleomorphic adenomas or Warthin parotid tumours. Intraoperative facial nerve monitoring can be helpful during surgery. The lack of monitoring would not be considered a contraindication for surgery.

Late traumatic aneurysm of the superficial temporal artery

A 47-year-old female presents with a pulsatile left temporal mass, which has been slowly enlarging over the past 3 years. She sustained blunt head trauma 10 years prior from a motor vehicle collision with no subsequent reported injury. Her presenting symptoms include headache, constant audible pulsation, and paresthesias over the left temporal region. Magnetic resonance angiography and computed tomography confirmed the presence of a 5.5 cm (length) 2.3 cm (diameter) proximal superficial temporal artery aneurysm (STA) with feeding branches from the middle temporal artery (A) and (B, Cover). The operative approach included a longitudinal incision directly overlying the aneurysm extending from the preauricular region to the temporal region. The proximal STA, which was nonaneurysmal, was dissected and ligated that rendered the aneurysm nonpulsatile (C). The aneurysm was exposed and dissected along its posterior aspect to avoid injury to the temporal branches of the facial nerve, which traverse anteriorly. The additional feeding branches were ligated, and the entire aneurysm was excised. The patient demonstrated no focal deficits on postoperative cranial nerve examination and remained stable in long-term follow-up. Aneurysms of the superficial temporal are rare and are usually degenerative because of blunt or penetrating trauma to the preauricular or temporal region. True aneurysms of the STA have also been described in isolated case reports. The anterior branch of the STA is most frequently affected. Symptoms may include headache, constant pulsatility, visual disturbances, dizziness, ear discomfort, and hemorrhage. Compression of the proximal superficial temporal artery in the preauricular region frequently diminishes pulsatility and flow. Treatment of choice is ligation of the STA and feeding branches with aneurysm excision. For aneurysms of the proximal STA, temporal branches of the facial nerve are present anteriorly and may cause facial hemiparesis if injured. Although not used in this patient, intraoperative facial nerve monitoring may help avoid iatrogenic injury.