A multi-institutional machine learning algorithm for prognosticating facial nerve injury following microsurgical resection of vestibular schwannoma.

Vestibular schwannomas (VS) are the most common tumor of the skull base with available treatment options that carry a risk of iatrogenic injury to the facial nerve, which can significantly impact patients' quality of life. As facial nerve outcomes remain challenging to prognosticate, we endeavored to utilize machine learning to decipher predictive factors relevant to facial nerve outcomes following microsurgical resection of VS. A database of patient-, tumor- and surgery-specific features was constructed via retrospective chart review of 242 consecutive patients who underwent microsurgical resection of VS over a 7-year study period. This database was then used to train non-linear supervised machine learning classifiers to predict facial nerve preservation, defined as House-Brackmann (HB) I vs. facial nerve injury, defined as HB II-VI, as determined at 6-month outpatient follow-up. A random forest algorithm demonstrated 90.5% accuracy, 90% sensitivity and 90% specificity in facial nerve injury prognostication. A random variable (rv) was generated by randomly sampling a Gaussian distribution and used as a benchmark to compare the predictiveness of other features. This analysis revealed age, body mass index (BMI), case length and the tumor dimension representing tumor growth towards the brainstem as prognosticators of facial nerve injury. When validated via prospective assessment of facial nerve injury risk, this model demonstrated 84% accuracy. Here, we describe the development of a machine learning algorithm to predict the likelihood of facial nerve injury following microsurgical resection of VS. In addition to serving as a clinically applicable tool, this highlights the potential of machine learning to reveal non-linear relationships between variables which may have clinical value in prognostication of outcomes for high-risk surgical procedures.

Immediate Facial Nerve Palsy Secondary to Otological Surgery: A Systematic Review and Narrative Synthesis.

OBJECTIVES: Iatrogenic facial nerve palsy following otological surgery is a devastating complication that results in adverse aesthetic and functional outcomes. This study aims to review studies that have reported cases of immediate facial nerve palsy to learn why and where injuries occurred and to assess outcomes following management. DATABASES REVIEWED: MEDLINE, Embase, Cochrane CENTRAL, and Pubmed up to June 20, 2023. METHODS: Clinical studies of immediate facial nerve palsies following middle ear and cochlear implantation surgery were included. Risk of bias was examined using the Brazzelli risk of bias tool. Due to the inconsistency in reporting of outcomes, we were unable to perform a meta-analysis. RESULTS: Of 234 studies identified, 11 met the inclusion criteria. The most common causes of injury were excessive drilling, use of sharp hooks to remove disease, or disorientation of the surgeon secondary to bleeding or inflammation. Variable usage of preoperative computed tomography (CT) imaging and intraoperative facial nerve monitoring was reported. The tympanic segment was the most common site of injury. A variety of surgical techniques were employed to approach the facial nerve injury including facial nerve decompression, direct closure, and repair using an autologous nerve graft. CONCLUSIONS: Otological surgeons should consider utilizing preoperative CT imaging to establish a three-dimensional mental image of key landmarks and anatomical variations before embarking on surgery. Intraoperative FN monitoring enables safe practice. Despite these measures, complex disease processes and hostile intraoperative conditions can present difficulty. Multiple treatment options are available to treat the underlying injury.

Management of facial nerve trauma.

PURPOSE OF REVIEW: To present the current literature on management of facial nerve disorder secondary to trauma, with a focus on the utility of electrodiagnostic testing in this setting. RECENT FINDINGS: Patients with facial palsy related to temporal bone fractures should be started on high-dose corticosteroids as early as possible. Recent literature on the benefit of surgical intervention in the setting of temporal bone fracture is mixed. Some studies support early surgical decompression whereas others have found no benefit compared with conservative treatment. SUMMARY: The management of facial nerve trauma is based on location and extent of injury. Extratemporal trauma and transected nerve should be treated with surgical exploration and tension-free coaptation ideally within 72 h. There are no guidelines for intratemporal facial nerve trauma. Surgical decompression compared with medical management is debated in the literature without consensus and more large studies are needed.

Modified Endaural Approach With a Peripheral Dissection of the Superficial Musculoaponeurotic System to Access the Temporomandibular Joint to Prevent Facial Nerve Injury.

The purpose of this study was to assess the effects of protecting the facial nerve with a modified endaural approach with a peripheral dissection of the superficial musculoaponeurotic system to access the temporomandibular joint which allows an excellent operative field of visualization, multiple surgical procedures of the temporomandibular joint, and general care which improves the immediate postoperative period, making this a less morbid surgery. This study included 33 patients (39 sides) who underwent surgical treatment for disorders of the temporomandibular joint from the years 2021 to 2023 at the maxillofacial department of the clinic "Colsanitas" located in Bogota, Colombia. Therapeutic results were evaluated by postoperative facial nerve injury, with the House-Brackman scale; every patient was examined for adequate facial musculature function immediately after surgery. Notably, zero patients presented facial nerve injury. These results imply that the modified endaural approach with a peripheral dissection of the superficial musculoaponeurotic system to access the temporomandibular joint reduces the incidence of facial nerve injuries, improves operative site exposure, and lowers the frequency of complications.

Subclassification of Koos grade 4 vestibular schwannoma: insights into tumor morphology for predicting postoperative facial nerve function.

OBJECTIVE: Koos grade 4 vestibular schwannoma (KG4VS) is a large tumor that causes brainstem displacement and is generally considered a candidate for surgery. Few studies have examined the relationship between morphological differences in KG4VS other than tumor size and postoperative facial nerve function. The authors have developed a landmark-based subclassification of KG4VS that provides insights into the morphology of this tumor and can predict the risk of facial nerve injury during microsurgery. The aims of this study were to morphologically verify the validity of this subclassification and to clarify the relationship of the position of the center of the vestibular schwannoma within the cerebellopontine angle (CPA) cistern on preoperative MR images to postoperative facial nerve function in patients who underwent microsurgical resection of a vestibular schwannoma. METHODS: In this paper, the authors classified KG4VSs into two subtypes according to the position of the center of the KG4VS within the CPA cistern relative to the perpendicular bisector of the porus acusticus internus, which was the landmark for the subclassification. KG4VSs with ventral centers to the landmark were classified as type 4V, and those with dorsal centers as type 4D. The clinical impact of this subclassification on short- and long-term postoperative facial nerve function was analyzed. RESULTS: In this study, the authors retrospectively reviewed patients with vestibular schwannoma who were treated surgically via a retrosigmoid approach between January 2010 and March 2020. Of the 107 patients with KG4VS who met the inclusion criteria, 45 (42.1%) were classified as having type 4V (KG4VSs with centers ventral to the perpendicular bisector of the porous acusticus internus) and 62 (57.9%) as having type 4D (those with centers dorsal to the perpendicular bisector). Ventral extension to the perpendicular bisector of the porus acusticus internus was significantly greater in the type 4V group than in the type 4D group (p < 0.001), although there was no significant difference in the maximal ventrodorsal diameter. The rate of preservation of favorable facial nerve function (House-Brackmann grades I and II) was significantly lower in the type 4V group than in the type 4D group in terms of both short-term (46.7% vs 85.5%, p < 0.001) and long-term (82.9% vs 96.7%, p = 0.001) outcomes. Type 4V had a significantly negative impact on short-term (OR 7.67, 95% CI 2.90-20.3; p < 0.001) and long-term (OR 6.05, 95% CI 1.04-35.0; p = 0.045) facial nerve function after surgery when age, tumor size, and presence of a fundal fluid cap were taken into account. CONCLUSIONS: The authors have delineated two different morphological subtypes of KG4VS. This subclassification could predict short- and long-term facial nerve function after microsurgical resection of KG4VS via the retrosigmoid approach. The risk of postoperative facial palsy when attempting total resection is greater for type 4V than for type 4D. This classification into types 4V and 4D could help to predict the risk of facial nerve injury and generate more individualized surgical strategies for KG4VSs with better facial nerve outcomes.

An Artificial Neural Network Model for Predicting Postoperative Facial Nerve Outcomes After Vestibular Schwannoma Surgery.

BACKGROUND AND OBJECTIVES: The emergence of machine learning models has significantly improved the accuracy of surgical outcome predictions. This study aims to develop and validate an artificial neural network (ANN) model for predicting facial nerve (FN) outcomes after vestibular schwannoma (VS) surgery using the proximal-to-distal amplitude ratio (P/D) along with clinical variables. METHODS: This retrospective study included 71 patients who underwent VS resection between 2018 and 2022. At the end of surgery, the FN was stimulated at the brainstem (proximal) and internal acoustic meatus (distal) and the P/D was calculated. Postoperative FN function was assessed using the House-Brackmann grading system at discharge (short-term) and after 9-12 months (long-term). House-Brackmann grades I-II were considered good outcome, whereas grades III-VI were considered fair/poor. An ANN model was constructed, and the performance of the model was evaluated using the area under the ROC curve for internal validation and accuracy, sensitivity, specificity, and positive and negative predictive values for external validation. RESULTS: The short-term FN outcome was grades I-II in 57.7% and grades III-VI in 42.3% of patients. Initially, a model using P/D had an area under the curve of 0.906 (internal validation) and an accuracy of 89.1% (95% CI: 68.3%-98.8%) (external validation) for predicting good vs fair/poor short-term FN outcomes. The model was then refined to include only muscles with a P/D with a proximal latency between 6 and 8 ms. This improved the accuracy to 100% (95% CI: 79%-100%). Integrating clinical variables (patient's age, tumor size, and preoperative HB grade) in addition to P/D into the model did not significantly improve the predative value. A model was then created to predict the long-term FN outcome using P/D with latencies between 6 and 8 ms and had an accuracy of 90.9% (95% CI: 58.7%-99.8%). CONCLUSION: ANN models incorporating P/D can be a valuable tool for predicting FN outcomes after VS surgery. Refining the model to include P/D with latencies between 6 and 8 ms further improves the model's prediction. A user-friendly interface is provided to facilitate the implementation of this model.

Mandibular condylar fractures: a 5-year retrospective analysis comparing open versus closed reduction.

BACKGROUND: Mandibular fractures are common facial fractures, and contemporary management of mandibular condylar fractures is controversial. The purpose of this study was to compare the outcomes of patients who sustained a mandibular condylar fracture between 2016 and 2020, who were managed by either open or closed techniques. The outcomes of this study were: post-operative facial nerve function, occlusion, and maximal mouth opening. METHODS: This study is a retrospective multicentre cohort study which assessed clinical records for 246 patients with mandibular condyle fractures in three hospitals in Perth, Western Australia. The primary outcome measure was changes in post-operative facial nerve function. RESULTS: One hundred and thirty-two patients underwent open reduction and internal fixation (ORIF), and 114 patients had closed management. The overall rate of temporary facial nerve injury following ORIF was 3.28%. The overall rate of permanent facial nerve injury was 0.82%. Sialocoele occurred in 2.46% of all patients who underwent ORIF. 6.14% of patients had persisting malocclusion across both groups. There was a statistically significant association between the degree of fragment shortening and facial nerve injury (P = 0.0063), with more facial nerve changes in the group with 5 mm or greater of fragment shortening. CONCLUSIONS: There is still significant debate over the management of mandibular condylar injuries. This study demonstrates a similar rate of temporary and permanent facial nerve injury as previously described, as well as a similar rate of sialocoele occurrence. Further prospective studies may provide clarity about important characteristics that will help guide decision making for mandibular condylar fractures.

Delayed facial palsy after resection of vestibular schwannoma: does it influence long-term facial nerve functional outcomes?

OBJECTIVE: Delayed facial palsy (DFP) is a common and unique complication after resection of vestibular schwannoma (VS). Few studies have focused on the clinical question of whether patients with DFP can be expected to have the same long-term prognosis in terms of facial nerve function as those without DFP based on their facial nerve function immediately postoperatively. This study aimed to clarify the clinical impact of DFP on the long-term functional status of the facial nerve after VS resection. METHODS: The authors retrospectively reviewed patients with sporadic VS who were treated surgically via a retrosigmoid approach between January 2002 and March 2020. DFP was defined as de novo deterioration of facial nerve function by a House-Brackmann (HB) grade ≥ I more than 72 hours postoperatively. The incidence of DFP after VS resection and its impact on long-term facial nerve function were analyzed. RESULTS: DFP developed in 38 (14.3%) of 266 patients who met the inclusion criteria. The median latency until DFP onset postoperatively was 8.5 days. When facial nerve function was normal immediately postoperatively, the rate of preservation of favorable facial nerve function (HB grade I or II) at 24 months postoperatively was 100% for all patients regardless of whether they developed DFP. In contrast, when facial nerve dysfunction was present immediately postoperatively, the rate of preservation of favorable facial nerve function at 24 months postoperatively was significantly lower in patients with DFP than in those without DFP (77.8% vs 100% in patients with HB grade II immediately postoperatively, p = 0.001; 50.0% vs 90.3% in those with HB grade III immediately postoperatively, p = 0.042). DFP development had a significantly negative impact on the long-term functional status of the facial nerve postoperatively when age, tumor size, and HB grade immediately postoperatively were taken into account (OR 0.04, 95% CI 0.01-0.20; p < 0.001). CONCLUSIONS: DFP can be a minor complication when normal facial nerve function is observed immediately after surgery. However, when facial nerve dysfunction is present immediately after surgery, even if mild, the long-term prognosis for facial nerve function is significantly worse in patients with DFP than in those without DFP.

The "low preauricular" transmasseteric anteroparotid (TMAP) technique as a standard way to treat extracapsular condylar fractures.

Condylar fracture treatment is a debated topic among maxillofacial surgeons. Various surgical techniques are used today, each one with advantages and disadvantages. The aim of this study is to present and evaluate our technique adopted for treatment of any type of extracapsular condylar fractures. Between 2020 and 2022, 16 condylar fractures were treated. In two patients with bilateral condylar fractures, the present technique was compared to the mini-retromandibular approach. All the patients were checked for clinical and radiological outcomes, facial nerve injury, scar visibility and presence of salivary complications. Dental occlusion was always restored, and facial nerve damage or salivary disorders were not observed. The skin incision, limited to the caudal two-thirds of the auricle, made the scar almost invisible and greatly improved the surgical field in the condylar neck area, facilitating the treatment. The proposed technique provides easier internal fixation for both neck and base condylar fractures with good cosmetic results, ensuring better protection of the facial nerve and parotid gland. The surgical technique described has not shown disadvantages in terms of operational difficulty, results, and complications. This novel surgical technique could represent a new choice in the treatment of extracapsular condylar fractures, although further studies are needed to support this new proposal.

Application of diffusion tensor imaging of the facial nerve in preoperative planning for large vestibular schwannoma: a systematic review.

The accurate identification and preservation of the facial nerve (FN) during vestibular schwannoma (VS) surgery is crucial for maintaining facial function. Investigating the application of diffusion tensor imaging (DTI) in preoperative planning for large VS surgery is provided. PubMed, Cochrane Library, Science Direct, ISI Web of Science, Embase, and additional sources were searched to identify cohort studies about the preoperative DTI usage for the FN tracking before large VS (≥ 2.5 cm) surgery published between 1990 and 2023. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed; the Newcastle-Ottawa Scale was used to assess the risk of bias and to evaluate limitations based on selection/outcome biases. A total of 8 publications yielding 149 VS (mean size 3.66 ± 0.81 cm) were included. Surgical concordance with preoperative DTI FN tracking was 91.67% (range 85-100%). Overall DTI reliability was 88.89% (range 81.81-95.83%). Larger tumor size predicted either DTI inaccurate finding or complete DTI failure (p = 0.001). VS size above > 3.5 cm was associated with a higher risk of DTI failure (p = 0.022), with a higher risk of inaccurate DTI finding preoperatively (p = 0.033), and with a higher House-Brackman score postoperatively (p = 0.007). Application of DTI in larger VS surgery is a valuable FN identification along with electrophysiological monitoring and neuronavigation, therefore also in its preservation and in lowering risk of complications. DTI represents a valuable adjunct to electrophysiological monitoring and neuronavigation in FN identification, applicable not only for smaller, but also larger VS.

Optimizing Facial Function in Patients With High-Risk Recurrent Pleomorphic Adenoma and a History of Facial Nerve Injury.

BACKGROUND: Parotid pleomorphic adenoma (PA) patients present significant diagnostic and surgical challenges rendering them high risk for facial nerve injury. Recurrent PA patients often present with history of facial nerve injury or previous reanimations making salvage of the facial nerve or previous reanimations significantly more complex. The study aim is to share our experience with this high risk for facial nerve injury population and review the literature. METHODS: Adult patients with recurrent PA and history of facial nerve injury with at least 3 months of follow-up were analyzed for demographics, facial palsy history, previous head and neck surgeries, previous facial paralysis reconstruction, preoperative imaging, surgical approach, and postoperative outcomes. RESULTS: Four female patients were identified with an average age of 62 years. All patients underwent an initial protective dissection of the facial nerve or previous reanimation reconstruction by the facial nerve reconstructive team followed by the extirpative team. The average number of previous head and neck surgeries was 5, the number of recurrences was 2, and follow-up was 20 months. Half had prior dynamic facial reanimation. Two patients underwent complete preextirpative dissection of the facial nerve resulting in neuropraxia, which recovered completely after an average of 143 days. A third patient presented with 2 recurrences, both during and after reanimation with a dually innervated free functional muscle transfer. The reconstruction was salvaged, and motion was achieved. A fourth patient presented with benign preoperative findings, but intraoperative findings confirmed malignancy, necessitating facial nerve sacrifice, followed by immediate intratemporal grafting of the facial nerve and masseteric nerve transfer. Motion appeared 139 days postoperatively. CONCLUSIONS: A multidisciplinary effort should be implemented in this high risk for facial nerve injury population with the primary goal of protecting the facial nerve or any previous reanimation procedures, yet with preparedness to apply any reconstructive strategy based on intraoperative findings.

[Professor LI De-hua's experience in treating facial nerve injury after total parotidectomy with blade needle based on jingjin theory].

The paper summarizes the academic thought and clinical experience of professor LI De-hua in treatment of facial nerve injury after total parotidectomy with blade needle based on jingjin (muscle region of meridian, sinew/fascia) theory. This disease is located at muscle regions of hand-/foot-three yang meridians; and the sinew/fascia adhesion is its basic pathogenesis, manifested by "transversely-distributed collaterals" and "knotted tendons". In treatment, the knotted tendons are taken as the points. Using the relaxation technique of blade needle, the lesions of sinews/fascia are dissected and removed to release the stimulation or compression to the nerves and vessels so that the normal function of sinews/fascia can be restored.

Treatment of extracapsular fractures of the mandibular condylar process: A retrospective evaluation of 377 cases.

BACKGROUND/AIM: Mandibular condylar fractures represent 25%-35% of all mandibular fractures. Despite profound research, there is still a controverse debate about treating these fractures conservatively or by open reduction and internal fixation (ORIF). The aim of this study is to analyse the outcome after open and closed treatment of extracapsular mandibular condyle fractures regarding general characteristics, post-treatment malocclusion, facial nerve palsy (FNP), maximum mouth opening (MMO) and parotid complications. METHODS: A retrospective cohort of 377 fractures (350 open, 27 closed treatment) was reviewed by reference to clinical and radiological pre- and postoperative documentation. Follow-up period was 12 months. Pearsons' chi-square-test, correlations, Kruskal-Wallis test and t-test were carried out for statistical analysis. RESULTS: The dominant type of fracture was type II in Spiessl and Schroll classification (50.1%). In the open treated fractures, the most common approach was retromandibular transparotid (91.7%). Post-treatment malocclusion occurred in 18.0% and was significantly increased in bilateral fractures (p = .039), in luxation fractures (p = .016) and in patients with full dentition (p = .004). After open reduction and internal fixation (ORIF), temporary FNP was documented in 7.1% whereas a permanent paresis occurred in 1.7%. FNP was significantly associated with high fractures (p = .001), comminution (p = .028) and increased duration of surgery (p = .040). Parotid complications were significantly associated with revision surgery (p = .009). Post-treatment reduction of MMO mainly occurred in female patients (p < .001) as well as in patients with bilateral fractures (p < .001), high fractures (p = .030) and concomitant mandibular (p = .001) and midfacial fractures (p = .009). CONCLUSION: Malocclusion seems to be the most frequent long-term complication after open reduction and osteosynthesis of extracapsular mandibular condyle fractures. We suggest ORIF by a transparotid approach to be an appropriate treatment with a low complication rate regarding especially FNP for extracapsular fractures of the mandibular condyle.

Predicting postoperative facial nerve paralysis by using intraoperative nerve monitoring during parotid surgery.

OBJECTIVES: To investigate a method for predicting postoperative facial nerve paralysis (POFNP) during parotid surgery using intraoperative nerve monitoring (IONM). METHODS: We assessed prediction for POFNP by using IONM, comparing between stimulation in the facial nerve trunk and each branch by using facial nerve monitoring. The amplitude response ratio (ARR) was calculated for the trunk/periphery. In addition, we then examined the correlation between ARR and time to recovery of paralyzed branches. RESULTS: 372 branches of 93 patients did not develop POFNP and were classified as group A. Among 20 patients who developed POFNP, 51 branches without POFNP were classified as group B, and 29 branches with POFNP were classified as group C. The ARR was approximately 1 in group A and B. but less than 0.5 in all branches in Group C. When the cut off value of ARR was set at 0.55, the sensitivity, specificity, and accuracy of POFNP diagnosis by ARR were 96.5%, 93.1%, and 96.8%, respectively. CONCLUSION: Using IONM during parotid surgery enables easy prediction of POFNP.

Facial palsy after orthognathic surgery: A systematic review.

It was the aim of the systematic review to evaluate the incidence of facial palsy following orthognathic surgery, and to assess the possible mechanisms of injury, subsequent management, and eventual outcomes. The protocol of this systematic review was registered in the International Prospective Register of Systematic Reviews. A thorough search of PubMed, Scopus, Cochrane Library, and CINAHL databases up to April 2022 was conducted. In total, 34 articles were selected for this review, including 54 facial palsies in 53 patients. The incidence of facial palsy was estimated to range from 0.04% to 0.77%. Most of the possible etiologies proposed involved intraoperative nerve compression or postoperative edema. Physical therapy and steroid administration were the most frequently employed management approaches. Surgical exploration for the facial nerve was executed in one patient. Forty-three facial palsies (79.6%) attained complete recovery with conservative management, whereas 11 facial palsies (20.4%) continued to show incomplete recovery during the follow-up period. Earlier facial palsy onset (timing after surgery) was related to a higher risk of continuing palsy (p = 0.018). Within the limitations of this review it seems that facial palsy following orthognathic surgery should be treated conservatively whenever appropriate.

Surgical and nonsurgical treatment outcomes in traumatic facial nerve palsy.

PURPOSE: Facial nerve decompression surgery is performed on patients with immediate, complete traumatic facial palsy. However, the clinical advantage of the surgical treatment has weak evidence because of lack of control groups in previous studies. Therefore, this study compared facial function outcomes between the patients who underwent surgery and those who did not. Furthermore, in cases of bilateral traumatic facial palsy, the outcomes of the surgical and nonsurgical sides were also discussed. METHODS: A retrospective medical chart review of immediate and severe (House-Brackman [HB] grade V and VI) traumatic facial palsy was conducted. Twenty-five ears from the surgical group and eight ears from the conservative treatment group were enrolled. Among the patients, three with immediate and severe bilateral facial palsy underwent unilateral surgery. RESULTS: The average HB grade after 1-year follow-up was 1.7 in the surgical group and 1.5 in the nonsurgical group. Four patients who have definite facial canal disruption in the imaging study have recovered to HB grades I-III without surgical intervention. In patients with bilateral facial palsy, the nonsurgical side showed the same or better facial functions than the surgical side. CONCLUSIONS: Compared with nonsurgical conservative treatment, facial nerve decompression surgery did not show superior outcomes in immediate HB grade V-VI traumatic facial palsy. The clinical advantage of facial nerve decompression is questionable and should be re-evaluated in a prospectively designed study.

Endoscopic vs microscopic facial nerve decompression for traumatic facial nerve palsy: a randomized controlled trial.

PURPOSE: To explore a minimally invasive trans-canal endoscopic facial nerve decompression for traumatic facial nerve palsy and compare it with microscopic facial nerve decompression. METHODS: 35 and 38 patients underwent endoscopic and microscopic facial nerve decompression, respectively, for traumatic facial nerve palsy. Onset of symptoms, type of temporal bone fracture, day of surgical intervention following trauma, ossicular chain status and nature of insult to facial nerve were observed. Time period for recovery (House Brackmann grade ≤ 3), long term recovery rates, pre- and post-operative hearing status, surgical time and post-operative pain were compared between groups. RESULTS: Maximum patients in endoscopic and microscopic groups (77.1% and 76.3%, respectively) had acute onset of symptoms. 57.1% (20/35) had longitudinal, 17.1% (6/35) had transverse and 25.7% (9/35) had mixed fractures in endoscopic group. In the microscopic group, 57.9% (22/38) had longitudinal, 18.4% (7/38) had transverse and 23.7% (9/38) had mixed fractures. The mean (± S.D.) post-operative air-bone gap in endoscopic and microscopic group were 16.47 ± 4.5 dB and 19.4 ± 5.2 dB, respectively, which was statistically significant. The mean (± S.D.) time period for recovery of endoscopic and microscopic groups were 14.4 ± 5 days and 22.5 ± 7 days, respectively (p value < 0.05). The difference in post-operative pain between the two groups was also statistically significant. The difference in long term recovery rates was not statistically significant (p > 0.05). CONCLUSIONS: Endoscopic facial nerve decompression results in early recovery, less post-operative pain and better post-operative air-bone gap closure when compared to conventional microscopic technique.

Feasibility of facial nerve monitoring using adhesive surface electrodes during parotidectomy: a comparative study with needle electrodes.

PURPOSE: Electrophysiological monitoring of the facial nerve during parotidectomy has been reported as an adjunctive method to prevent facial nerve injury. Classically, a needle electrode is used to obtain electromyographic (EMG) signals from facial muscles during facial nerve monitoring (FNM) of parotid surgery, likewise adhesive surface electrodes. This study aimed to investigate the feasibility of performing FNM with surface electrodes during parotid surgery and to compare EMG values with needle electrodes. METHODS: Thirty patients who underwent parotidectomy under FNM using adhesive surface and needle electrodes were included. Two pairs of adhesive surface electrodes and needle electrodes were used for FNM during parotid surgery. Mean amplitudes were collected after electrical facial nerve stimulation at 1 mA after specimen removal. RESULTS: The mean amplitude of the adhesive surface electrodes was 226.50 ± 118.44 µV (orbicularis oculi muscle) and 469.6 ± 306.06 µV (orbicularis oris muscle), respectively. The mean amplitude of the needle electrodes was 449.85 ± 248.10 µV (orbicularis oculi muscle) and 654.66 ± 395.71 µV (orbicularis oris muscle), respectively. The mean amplitude of the orbicularis oris muscle was significantly greater than that of the orbicularis oculi. The amplitude values measured in the orbicularis oculi muscle showed significant differences between the needle and skin electrodes. CONCLUSIONS: Facial nerve monitoring (FNM) using adhesive surface electrodes is feasible in parotid surgery. Although the mean amplitude value of the surface electrode was relatively lower than that of the needle electrode, the surface electrode is considered a feasible and safe EMG recording device for FNM in parotid surgery.