Optimizing Location of Subdermal Recording Electrodes for Intraoperative Facial Nerve Monitoring.

OBJECTIVE: The purpose of this study is to determine if different facial muscle groups demonstrate different responses to facial nerve stimulation, the results of which could potentially improve intraoperative facial nerve monitoring (IOFNM). METHODS: IOFNM data were prospectively collected from patients undergoing cochlear implantation. At different stages of nerve exposure, three sites were stimulated using a monopolar pulse. Peak electromyography (EMG) amplitude (µV) in four muscle groups innervated by four different branches of the facial nerve (frontalis-temporal, inferior orbicularis oculi-zygomatic, superior oribularis oris-buccal, and mentalis-marginal mandibular) were recorded. RESULTS: A total of 279 peak EMG amplitudes were recorded in 93 patients. At all three stimulating sites, the zygomatic branch mean peak EMG amplitudes were statistically greater than those of the temporal, buccal, and marginal mandibular branches (P < .05). At stimulating Site C, the marginal mandibular branch mean peak EMG was stronger than the temporal or buccal branches (P < .05). Of the 279 stimulations, the zygomatic branch demonstrated the highest amplitude in 128 (45.9%) trials, followed by the marginal mandibular branch (22.2%). CONCLUSIONS: When utilized, IOFNM should be performed with at least two electrodes, one of which is placed in the orbicularis oculi muscles and the other in the mentalis muscle. However, there is wide variability between patients. As such, in cases of suspected variant nerve anatomy or increased risk of injury (intradural procedures), surgeons should consider using more than two recording electrodes, with at least one in the orbicularis oculi muscle. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:E2329-E2334, 2021.

Reliability of Preoperative Prediction of the Location of the Facial Nerve Using Diffusion Tensor Imaging-Fiber Tracking in Vestibular Schwannoma: A Systematic Review and Meta-Analysis.

The popularization and application of microscopy, the in-depth study of the microanatomy of the cerebellopontine angle, and the application of intraoperative electrophysiological monitoring technology to preserve facial nerve function have laid a solid foundation for the modern era of neurosurgery. The preoperative prediction of the location of the facial nerve is a long-desired goal of neurosurgeons. The advances in neuroimaging seem to be making this goal a reality. Many studies investigating the reliability of the preoperative prediction of the location of the facial nerve using diffusion tensor imaging-fiber tracking in vestibular schwannoma have been reported in the last 20 years. The PubMed, Embase, and Cochrane databases were searched for articles published before March 30, 2020. A comprehensive review of published studies was carried out in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Authors performed a systematic review and meta-analysis of the reported data to assess the reliability of the preoperative prediction of the location of the facial nerve using diffusion tensor imaging-fiber tracking in vestibular schwannoma. The data were analyzed using a fixed-effects model. The estimated overall intraoperative verification concordance rate was 89.05% (95% confidence interval 85.06%-92.58%). Preoperatively predicting the location of the facial nerve using diffusion tensor imaging-fiber tracking in vestibular schwannoma is reliable, but the extent to which it contributes to long-term facial nerve function is still unclear. To further verify these results, studies with larger sample sizes are needed in the future, especially prospective randomized controlled trials focusing on the long-term functional preservation of the facial nerve.

Is there a relationship between mastoid pneumatisation and facial canal dimensions?

OBJECTIVE: To evaluate mastoid pneumatisation and facial canal dimensions. METHOD: In this retrospective study, 169 multidetector computed tomography scans of temporal bone were reviewed. Facial canal dimensions were evaluated at the labyrinthine, tympanic and mastoid segments using axial and coronal multidetector computed tomography scans of temporal bone. Mastoid pneumatisation and facial canal dehiscence were evaluated. Facial canal dehiscence was measured if it was found to be present. RESULTS: This study showed that facial canal dimensions decreased in pneumatised mastoids. Facial canal dimensions in females were smaller than in males. Facial canal dehiscence was detected in 5.9 per cent and 6.5 per cent of the patients on the right and left sides, respectively. No correlations were found between facial canal dehiscence and mastoid pneumatisation. The length of dehiscence was 1.92 ± 0.44 mm (range, 0.86-2.51 mm) on the left side. In older subjects, left facial canal dehiscence was detected more, and the length of the dehiscence increased. CONCLUSION: This study concluded that during surgery, facial canal dehiscence should be kept in mind in order to avoid complications.

Traumatic Injury of the Petrous Part of the Temporal Bone: Keys for Reporting a Complex Diagnosis. / Patología traumática de peñascos, un diagnóstico complejo. Claves para el informe.

Fractures of the petrous part of the temporal bone are a common lesion of the base of the skull; most of these fractures result from high-energy trauma. In patients with multiple trauma, these injuries can be detected on CT scans of the head and neck, where the direct and indirect signs are usually sufficient to establish the diagnosis. It is important to these fractures because the temporal bone has critical structures and the complexity of this region increases the risk of error unless special care is taken. This article reviews the key anatomical points, the systematization of the imaging findings, and the classifications used for temporal bone fracture. We emphasize the usefulness of identifying and describing the findings in relation to important structures in this region, of looking for unseen fractures suspected through indirect signs, and of identifying anatomical structures that can simulate fractures. We point out that the classical classifications of these fractures are less useful, although they continue to be used for treatment decisions.

Comparison between early and delayed facial nerve decompression in traumatic facial nerve paralysis - A retrospective study.

Purpose To study the intraoperative findings in case of early and delayed decompression of facial nerve paralysis and compare their results. Methods Retrospective data analysis of 23 cases of longitudinal temporal bone fracture with House-Brackmann grade V and VI facial nerve paralysis. All cases were thoroughly evaluated and underwent facial nerve decompression through the transmastoid approach. All cases were under regular follow-up till the date of manuscript submission. Results Clinical improvement of the facial nerve function was observed for early vs. delayed facial nerve decompression. In the early decompression group, facial nerve function improved to grade II in eight cases (80%) and grade III in two cases (20%), whereas in the delayed decompression group it improved to grade II in one case (7.70%), grade III in four cases (30.76%), grade IV in seven cases (53.84%), and grade V in one case (7.70%). Conclusions Early decompression of facial nerve provides better results than delayed decompression because it enables early expansion of the nerve.

Comparison between early and delayed facial nerve decompression in traumatic facial nerve paralysis - A retrospective study

ABSTRACT Purpose To study the intraoperative findings in case of early and delayed decompression of facial nerve paralysis and compare their results. Methods Retrospective data analysis of 23 cases of longitudinal temporal bone fracture with House-Brackmann grade V and VI facial nerve paralysis. All cases were thoroughly evaluated and underwent facial nerve decompression through the transmastoid approach. All cases were under regular follow-up till the date of manuscript submission. Results Clinical improvement of the facial nerve function was observed for early vs. delayed facial nerve decompression. In the early decompression group, facial nerve function improved to grade II in eight cases (80%) and grade III in two cases (20%), whereas in the delayed decompression group it improved to grade II in one case (7.70%), grade III in four cases (30.76%), grade IV in seven cases (53.84%), and grade V in one case (7.70%). Conclusions Early decompression of facial nerve provides better results than delayed decompression because it enables early expansion of the nerve.

Temporal bone fracture: Evaluation in the era of modern computed tomography.

BACKGROUND: Temporal bone fractures (TBFs) are harbingers of high energy head trauma that can result in a variety of significant complications of the auditory, vestibular, nervous, and vascular systems. Multiple cohort studies have identified the incidence and proper evaluation of these fractures. We hypothesize that these have changed with the advent of modern high resolution computer tomography (CT) imaging. METHODS: We performed a retrospective review of all TBFs admitted to an urban level one trauma center between June 1, 2011 and May 31, 2015. A database was compiled including demographics, physical exam findings, imaging performed and results, morphology and directionality of fracture as well as outcomes and follow-up. RESULTS: One hundred thirteen patients were identified, representing 4.7% of skull fractures and 35.9% of skull base fractures. Most were subsequent to falls (41.6%) followed by pedestrian vehicular trauma (19.5%). The majority of TBF patients (67.3%) had additional fractures of the skull and 77.9% of TBF patients also had some kind of intracranial hemorrhage. The morphology of TBF and the overall mortality (7.9%) was consistent with previous reports. The incidence of facial nerve paralysis (1.6%), CSF leak (1.7%), and hearing loss (18.6%) were all lower than previously reported. Trauma imaging was able to identify 98.6% of TBF, calling the utility of routine temporal bone CT imaging into question. CONCLUSION: TBFs are less common than they once were and though they still carry a mortality rate similar to previously reported cohorts, the incidence of complications among survivors has dramatically improved. Additionally, modern CT imaging is very capable of identifying these injuries and dedicated temporal bone CT may only be of utility in cases where facial nerve injury or vascular injury is suspected. LEVEL OF EVIDENCE: Epidemiologic study, Level III.

Clinical features and outcomes of delayed facial palsy after head trauma.

OBJECTIVE: To investigate clinical features and outcomes of delayed facial palsy after head trauma. METHODS: The cases who had delayed facial palsy after head trauma treated from March 2008 to March 2013 at our hospital were enrolled in the study, and their clinical features and outcomes were analyzed. RESULTS: Thirty-five of 1620 cases developed delayed facial palsy after head trauma. Facial palsy occurred within day 3-7 in 23 cases, during day 8-14 in 8 cases, and 2 weeks later in 4 cases. Thirty-three cases were treated by prednisolone alone, and two cases who showed ≥90% degeneration of nerve fibers underwent surgical exploration and decompression. Among the 33 cases who received conservative treatment, 27 cases (81.8%) recovered completely, 3 cases (9.1%) recovered to Grade II, and only 3 cases (9.1%) recovered to Grade III or IV. The two surgically treated patients recovered to Grade II and III, respectively. CONCLUSION: The incidence of delayed facial palsy was 2.2% after head trauma. Delayed facial palsy mainly occurred within 2 weeks after head trauma. And over 90% patients achieved good recovery (HB Grade I or II) of facial nerve after conservative treatment.

Accuracy of high-resolution computed tomography in revealing fallopian canal fracture of patients with traumatic facial paralysis.

OBJECTIVES: To investigate accuracy of high-resolution computed tomography (HRCT) of temporal bone in revealing fallopian canal fracture among the patients with traumatic facial paralysis. METHODS: HRCT of temporal bone with cross-sectional scanning and multi-planar reformation (MPR) was performed on 31 patients with traumatic facial paralysis, and fracture sites of fallopian canal revealed by HRCT were retrospectively analyzed and compared with surgical findings. RESULTS: HRCT of temporal bone showed fracture of fallopian canal at geniculate ganglion in 25 cases, at tympanic segment in 15 cases, at labyrinthine segment in 5 cases, at pyramid segment in 2 cases, and at mastoid segment in one case, while surgical findings revealed that fracture involved geniculate ganglion in 27 cases, labyrinthine segment in 5, tympanic segment in 19, pyramid segment in 12, and mastoid segment in 9; the sensitivity of HRCT of temporal bone to detect fracture at such sites was 88.9%, 100%, 52.6%, 16.7% and 11.1%, respectively, and the specificity was 96.0%, 100%, 66.7%, 100% and 100%, respectively. CONCLUSION: HRCT of temporal bone was able to accurately reveal fracture of fallopian canal at geniculate ganglion and labyrinthine segment in the vast majority cases, but severely underestimated fracture at pyramid segment and mastoid segment of fallopian canal.

Using coronary computerized tomographic images to predict the bulging second genu of the facial nerve in mastoidectomy.

The aim of the present study is to determine whether coronary CT images of the temporal bone are useful to predict a bulging second genu of the facial nerve (SGFN) in mastoidectomy by measuring and comparing the heights of the SGFN above the prominence of the lateral semicircular canal (PLSC) in medial-to-lateral dimension on coronary CT images and in mastoidectomy. The relationship between the SGFN and the PLSC in medial-to-lateral dimension, which may have big variability, can be evaluated on the coronary CT images of the temporal bone. The heights of the SGFN above the PLSC in medial-to-lateral dimension were measured on coronary CT images and in mastoidectomy in 184 patients. If the SGFN is above the PLSC in medial-to-lateral dimension, we called the SGFN a bulging SGFN. The data measured on CT images and in surgery were described in histograms and compared. The sensitivity and the specificity in the diagnosis of a bulging SGFN on CT images were calculated by comparison with surgical measurement. Cohen's kappa coefficient was calculated. The heights of the SGFN above the PLSC measured in medial-to-lateral dimension varied from -2.9 to 2.9 mm on coronary CT images and varied from -3.0 to 3.0 mm in surgery. The data measured in surgery showed that the SGFN was above the PLSC in medial-to-lateral dimension in 27.7% (51/184) patients, at least 1 mm above the PLSC in 15.8% (29/184) patients and at least 2 mm above the PLSC in 6.0% (13/184) patients. The sensitivity and the specificity for CT diagnosis of a bulging SGFN were 100% (51/51) and 91.0% (121/133), respectively. Bulging SGFN can be predicted by measuring the height of the SGFN above the PLSC on coronary CT images of the temporal bone.

Accuracy of high-resolution computed tomography in locating facial nerve injury sites in temporal bone trauma.

In this study, high-resolution, multislice computed tomography findings are compared with surgical findings in terms of the fracture location in patients with traumatic facial paralysis. Patients with traumatic facial paralysis with grade VI House-Brackmann scale who met the criteria for surgical decompression between 2008 and 2012 were included in this study. All the patients underwent a multislice high-resolution, multislice computed tomography (HRCT) using 1-mm-thick slices with a bone window algorithm. The anatomical areas of the temporal bone (including the Fallopian canal) were assessed by CT and during the surgery (separately by the radiologist and the surgeon), and fracture line involvement was recorded. Forty-one patients entered this study. The perigeniculate area was the most commonly involved region (46.34 %) of the facial nerve. The sensitivity and specificity of HRCT to detect a fracture line seems to be different in various sites, but the overall sensitivity and specificity were 77.5 and 77.7 %, respectively. Although HRCT is the modality of choice in traumatic facial paralysis, the diagnostic value may differ according to the fracture location. The results of HRCT should be considered with caution in certain areas.

Post-traumatic peripheral facial nerve palsy: surgical and neuroradiological consideration in five cases of delayed onset.

The facial nerve is frequently injured after head trauma with or without temporal bone fractures. Computed tomography (CT) is the best procedure for detecting the fracture line at the level of the facial nerve canal and for assessing any associated lesions within the temporal bone. Magnetic resonance (MR) is required if there is a facial nerve paralysis, unexplained by CT findings. We present five cases of delayed post-traumatic facial nerve palsy without evidence of temporal bone fractures on CT, thus studied on MR. MR was essential for diagnosing the nerve impairment. Neuroradiological findings, clinical presentation, and electrodiagnostic tests influenced the management of the patients.

[High-resolution CT of temporal bone trauma: review of 38 cases]. / L'apport du scanner dans les traumatismes du rocher: à propos de 38 cas.

PURPOSE: Temporal bone trauma is frequent but difficult to assess due to the diversity of clinical presentations and complex anatomy. We have sought to assess the different types of fractures and complications on high-resolution CT. Materials and methods. Descriptive retrospective study over a 24 month period performed in the ENT radiology section of the Mohammed VI university medical center in Marrakech. A total of 38 cases of temporal bone trauma were reviewed. All patients underwent ENT evaluation and high-resolution CT of the temporal bone using 1mm axial and coronal sections. RESULTS: Mean patient age was 33 years (range: 14-55 years) with male predominance (sex ratio: 36/2). Clinical symptoms were mainly otorrhagia and conductive hearing loss. Oblique extra-labyrinthine fractures were most frequent. Two cases of pneumolabyrinth were noted. Management was conservative in most cases with deafness in 3 cases. CONCLUSION: High-resolution CT of the temporal bone provides accurate depiction of lesions explaining the clinical symptoms and helps guide management. MRI is complimentary to further assess the labyrinth and VII-VIII nerve complex.

Zygomatic root approach.

CONCLUSIONS: The zygomatic root (ZR) approach provides improved intraoperative exposure of the key areas around the geniculate ganglion without a craniotomy, combining the advantages of middle cranial fossa (MCF) and transmastoid extralabyrinthine (TMEL) approaches. The ZR approach may be useful in cases of traumatic facial palsy, Bell's palsy, iatrogenic facial palsy, superior semicircular canal dehiscence and primary cholesteatoma. OBJECTIVES: To describe and evaluate the new ZR approach technique in the treatment of traumatic intratemporal facial nerve injuries. PATIENTS AND METHODS: This is a prospective clinical study of three consecutive procedures performed between July 2007 and January 2008, and a detailed discription of the surgical technique. The setting is a tertiary referral center. The patients' age range was 3-7 years. Interventions were based on drilling the ZR area extensively, so that the perigeniculate area was exposed through the space created between the middle cranial fossa basal dura and skeletonized external auditory canal. The ZR approach can be performed as an isolated technique or can be combined with an inferior mastoidectomy protecting the bony bridge between. RESULTS: Two patients had a mixed-type fracture and one patient had a transverse fracture. All three patients received a ZR combined approach. There was no cerebrospinal fluid leak, hearing loss, tympanic membrane perforation or meatal stenosis.

[The diagnostic value of high resolution CT in assessment of temporal bone traumatic facial nerve paralysis].

OBJECTIVE: To investigate the diagnostic value of high resolution CT for temporal bone traumatic facial nerve paralysis and the guidance significance for surgery. METHOD: Twenty-nine patients of traumatic facial nerve paralysis were investigated. The predictive diagnosis was made according to the clinical data and the image features of HRCT, then a comparative analysis of the preoperative image features and the surgical findings were carried out. RESULT: The trend of temporal bone fracture displayed on the CT scan was basically consisted with the surgical findings. The direct CT signs of facial nerve injury include the bone fracture line went through the tube, bone tube rupture or continuity interruption, while the indirect CT signs include local incrassation of the facial nerve, lower bone density of the tube, geniculate fossa expansion, oppressed facial nerve, et al. The predictive diagnostic accordance rates of all the image features were above 90% as to the surgical findings. CONCLUSION: High resolution CT could localize the trend of temporal bone fracture,and is helpful to estimate the extent of facial nerve injury and other complications. High resolution CT could provide reliable basis for clinical diagnosis and treatment.

Diagnosis of the pathological exposure of the mastoid portion of the facial nerve by CT scanning.

CONCLUSIONS: High resolution CT imaging can provide useful information about the pathological exposure of the mastoid portion of the facial nerve before mastoid surgery and can assess the injury site of the facial nerve after operation. OBJECTIVES: To evaluate the diagnostic value of high resolution CT scanning of pathological exposure of the mastoid portion of facial nerve and provide valuable information for otologic surgery, and to analyse the cause of facial nerve paralysis after operation. MATERIALS AND METHODS: Routine CT scanning was used to examine patients with chronic suppurative otitis media and external auditory canal cholesteatoma preoperatively by axial-transverse and coronal views. If there was any pathological exposure of the mastoid portion of the facial nerve on CT imaging, then this was compared with intraoperative findings. In addition, one patient who had suffered postoperative facial nerve paralysis was also examined by CT scanning to determine whether any pre-existing pathological exposure of facial nerve could be found. RESULTS: Through routine CT scanning six patients with chronic suppurative otitis media and three patients with external auditory canal cholesteatoma were found to have pathological exposure of the mastoid portion of the facial nerve. Coronal views could more clearly show the size and the position of the exposure; the corresponding surgical findings (pathological exposure) for the facial nerve could be confirmed in all nine patients. CT imaging could also show that the patient who had suffered postoperative facial nerve paralysis did indeed have pre-existing pathological exposure of the mastoid portion of the facial nerve.