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Background: The petrosal artery supplies several structures at the skull base and is often the focus of various neurointerventional procedures. Therefore, knowledge of its anatomy and variations is important to surgeons and interventionalists., Materials and Methods: Twenty latex injected cadaveric heads (40 sides) underwent microsurgical dissection of the petrosal artery. Documentation of the course of the artery and its branches were made. Measurements of the petrosal artery's length and diameter were performed using microcallipers., Results: A petrosal artery was identified on all sides. The mean length and diameter of the artery within the middle cranial fossa was 2.4 cm and 0.38 mm, respectively. Branches included the following: dural, ganglionic, V3 branches, branches extending through the foramen ovale, branches directly to the greater petrosal and lesser petrosal nerves, branches to the floor of the hiatus of the greater and lesser petrosal nerves, branch to the arcuate eminence, and superior tympanic artery. No statistically significant differences were noted between male and female specimens, but right-sided petrosal arteries were in general, larger in diameter than left sides., Conclusions: A thorough anatomical knowledge of the petrosal artery and to its relationship to the facial nerve and other neurovascular structures is necessary to facilitate effective endovascular treatment and to preclude facial nerve complications.

Objective: Parasympathetic network damage results in facial nerve damage, sublingual ganglion degeneration, sublingual gland dysfunction, and dry mouth. In this study, subarachnoid hemorrhage (SAH) was considered to be the cause of dry mouth., Methods: We assessed 23 hybrid rabbits, including 5 control (group 1, Control). One milliliter of serum saline was injected into the cisterna magna of 5 animals (group 2). SAH was induced by injecting 1 mL of autologous blood into the cisterna magna of 13 animals (group 3). The animals were killed after 3 weeks of induction. The animals' sublingual ganglion and sublingual gland were excised for histopathological examination. The number of degenerated cells in the sublingual ganglion, secretory vesicles, and secretory granules in the sublingual gland that contain salivary components were estimated using Sequential Window Acquisition of All Theoretical Mass Spectra data analysis. The values were compared by the Mann-Whitney U-test., Results: The numbers of secretory vesicles in the sublingual gland were 5.3 ± 1.1 × 10 3 (group 1), 4.23 ± 0.45 × 10 3 (group 2), and 1.56 ± 0.22 × 10 3 (group 3); the numbers of secretory vesicles containing saliva in the sublingual gland were 324 ± 12.18 (group 1), 263 ± 36.23 (group 2), and 114 ± 23.14 (group 3); and the numbers of degenerated cells in the sublingual ganglion were 11 ± 3/mm 3 (group 1), 98.43 ± 15.54/mm 3 (group 2), and 346 ± 12.28/mm 3 (group 3) (P < 0.05)., Conclusions: Clinical findings in infection and diseases such as Sjögren syndrome, aseptic meningitis, and SAH are similar. However, until now, SAH has not been demonstrated experimentally to cause dry mouth. Discovering that SAH might cause dry mouth might prevent unnecessary use of antibiotics and decrease morbidity due to the wrong or late diagnosis., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objectives: At our institution, in vivo facial nerve mapping (FNM) is used during vascular anomaly (VAN) surgeries involving the facial nerve (FN) to create an FN map and prevent injury. During mapping, FN anatomy seemed to vary with VAN type. This study aimed to characterize FN branching patterns compared to published FN anatomy and VAN type., Study Design: Retrospective study of surgically relevant facial nerve anatomy., Methods: VAN patients (n = 67) with FN mapping between 2005 and 2018 were identified. Results included VAN type, FN relationship to VAN, FNM image with branch pattern, and surgical approach. A Fisher exact test compared FN relationships and surgical approach between VAN pathology, and FN branching types to published anatomical studies. MATLAB quantified FN branching with Euclidean distances and angles. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) analyzed quantitative FN patterns amongst VAN types., Results: VANs included were hemangioma, venous malformation, lymphatic malformation, and arteriovenous malformation (n = 17, 13, 25, and 3, respectively). VAN FN patterns differed from described FN anatomy (P < .001). PCA and HCA in MATLAB-quantified FN branching demonstrated no patterns associated with VAN pathology (P = .80 and P = .91, one-way analysis of variance for principle component 1 (PC1) and priniciple component 2 (PC2), respectively). FN branches were usually adherent to hemangioma or venous malformation as compared to coursing through lymphatic malformation (both P = .01, Fisher exact)., Conclusions: FN branching patterns identified through electrical stimulation differ from cadaveric dissection determined FN anatomy. This reflects the high sensitivity of neurophysiologic testing in detecting small distal FN branches. Elongated FN branches traveling through lymphatic malformation may be related to abnormal nerve patterning in these malformations., Level of Evidence: NA Laryngoscope, 130:2708-2713, 2020., (© 2020 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: To study the surgical anatomy of the labyrinthine artery (LA) and the subarcuate artery (SA), their anatomic relationships, and clinical implications, as injury of the LA can result in hearing loss., Methods: Ten formalin-fixed, latex-colored specimens were studied (20 sides). After retrosigmoid craniotomy and neurovascular dissection under microscopic magnification, 4-mm 0° and 30° endoscopic lenses were used to improve visualization. Results were statistically analyzed., Results: The LA was a constant artery that followed the vestibulocochlear nerve into the internal auditory canal. The SA was an inconstant artery that ended in the dura mater around the subarcuate fossa in 35% of cases. The LA originated from the anterior inferior cerebellar artery in 89.3% of specimens and from the basilar artery in 10.7% of specimens. The SA branched off from the anterior inferior cerebellar artery when present. The origin of the LA was inferomedial to the vestibulocochlear nerve in most cases (71.4%), whereas the SA was usually lateral (70%). The distal portion of the LA was inferomedial to the vestibulocochlear nerve in 71.4% of cases. The distal portion of the SA was superolateral to the nerve in all cases (P < 0.00001)., Conclusions: Knowledge of the different trajectory and anatomic relationship of the LA and the SA with the vestibulocochlear nerve is of paramount importance to differentiate them during surgery. The LA is usually inferomedial to the vestibulocochlear nerve at its distal and proximal aspects, whereas the SA usually originates lateral and ends superolateral to the nerve., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background and Purpose: Endovascular treatment of petrous dural AVFs may carry a risk of iatrogenic facial nerve palsy if the facial nerve arterial arcade, an anastomotic arterial arch that supplies the geniculate ganglion, is not respected or recognized. Our purpose was to demonstrate that the use of a treatment strategy algorithm incorporating detailed angiographic anatomic assessment allows identification of the facial nerve arterial arcade and therefore safe endovascular treatment., Materials and Methods: This was a retrospective cohort study of consecutive petrous dural AVF cases managed at Toronto Western Hospital between 2006 and 2018. Our standard of care consists of detailed angiographic assessment followed by multidisciplinary discussion on management. Arterial supply, primary and secondary treatments undertaken, angiographic outcomes, and clinical outcomes were assessed by 2 independent fellowship-trained interventional neuroradiologists., Results: Fifteen patients had 15 fistulas localized over the petrous temporal bone. Fistulas in all 15 patients had direct cortical venous drainage and received at least partial supply from the facial nerve arterial arcade. Following multidisciplinary evaluation, treatment was performed by endovascular embolization in 8 patients (53%) and microsurgical disconnection in 7 patients (47%). All patients had long-term angiographic cure, and none developed iatrogenic facial nerve palsy., Conclusions: By means of our treatment strategy based on detailed angiographic assessment and multidisciplinary discussion, approximately half of our patients with petrous AVFs were cured by endovascular treatment, half were cured by an operation, and all had preserved facial nerve function., (© 2020 by American Journal of Neuroradiology.)

Background: Decompression of the culprit artery causing hemifacial spasm (HFS), which passes between the facial nerve (cranial nerve [CN] VII) and the auditory nerve (CN VIII), can be difficult, especially if the artery compresses CN VII right after passing between the 2 nerves. Perforators or small arteries branching from near the compression site to adjacent structures can hinder the decompression process because such vessels can anchor the passing condition. The effect of such perforators or small arteries on the decompression process in such cases was investigated., Methods: The culprit artery passed between any part of CN VII and VIII in 59 of 396 consecutive patients with HFS who underwent microvascular decompression. The culprit artery compressed CN VII right after passing between the 2 nerves in 22 of the 59 cases. Direction of the perforators or small arteries from near the compression site and direction of decompression of the culprit artery were analyzed in these 22 cases., Results: Perforators or small arteries were observed in 20 cases, predominantly in the medial direction. The culprit artery was mobilized toward the petrous bone direction in most cases. No clear relationship was found between the 2 factors., Conclusions: Variation of curvature or tortuosity of the culprit artery and length of perforators or small branches may also have affected the decompression process and the directions. Adequate dissection near the compression site to obtain maximum mobilization of the culprit artery is necessary to achieve successful decompression in such cases., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Hemangioma of the facial nerve (FN) is a very rare benign tumor whose origin is the vascular plexi that surround the nerve. The transpetrous, retrosigmoid, and middle cranial fossa (MCF) routes are the traditional and most widely used approaches to reach these lateral skull base neoformations. However, this very complex region can be reached through an exclusive transcanal endoscopic procedure in selected cases. One of these was a 42-year-old patient who had been presenting a worsening left FN paralysis (grade VI according to the House-Brackmann scale at the time of visit) for 22 months without a history of trauma or infection. Radiological studies showed a lesion in the region of the geniculate ganglion. A suprageniculate endoscopic approach was performed to remove the lesion, with the sacrifice of the FN and a simultaneous hypoglossal-facial anastomosis. The aim of this minimally invasive surgery is the complete excision of the disease, maintaining the hearing function intact and restoration of facial function, whenever possible, avoiding more invasive approaches.

Objective: Facial nerve palsy (FNP) is a common disease in the otorhinolaryngological department. Besides the main symptom of motionlessness occurring in the ipsilateral facial muscles in FNP, there are other common complaints of numbness, stiffness and tightness in ipsilateral face described by the patients. Based on our pilot study, we further investigated the relevance between these complaints and facial microcirculation., Method: Function of facial microcirculation was evaluated by laser speckle contrast imaging (LCSI). Facial perfusion was measured in 143 patients with facial nerve palsy (FNP) at the first visit and follow-up visit under the same conditions., Results: Difference in FNP patients' facial microvascular perfusions between ipsilateral and contralateral side was significant (P = 0.0002613). Facial perfusion of patients with Bell's palsy (P = 00089) and facial nerve tumors (P = 0.025110) was significantly decreasing in the ipsilateral side. Improvement of perfusion could be seen after treatment., Conclusion: A positive correlation of FNP severity and microvascular impairment can be noticed. During treatment, patients' ipsilateral perfusion could increase. Therefore, this objective method can measure ipsilateral perfusion in the patients with FNP and the ipsilateral microvascular impairment can be detected through this method.

Aim: To understand possible mechanisms underlying lacrimal gland degeneration when facial nerve root ischemia induces pterygopalatine ganglion injury and subsequent dry eye in a rabbit model of subarachnoid hemorrhage., Material and Methods: Rabbits were divided into four groups: control, sham, moderate subarachnoid hemorrhage, and severe subarachnoid hemorrhage. Autologous blood recovered from the auricular artery was injected into the cisterna magna to induce subarachnoid hemorrhage in the two subarachnoid hemorrhage groups; animals were then monitored for dry eye development over 21 days before removal of their facial nerve roots, pterygopalatine ganglia, and lacrimal glands for immunohistochemical analyses. Neuronal viability in the pterygopalatine ganglia was measured; lacrimal gland vesicles were counted by stereological methods., Results: The mean tear-filled vesicle number and lacrimal gland volumes significantly decreased with an increase in facial nerve root injury severity and damaged neuron numbers in the pterygopalatine ganglion. Increase in injury severity most significantly decreased the tear-filled vesicle numbers in the pterygopalatine ganglion., Conclusion: Subarachnoid hemorrhage degenerates facial nerve parasympathetic branches entering the pterygopalatine ganglion, and neuronal density in this ganglion may be correlated with tear secretion. Our data suggest that pterygopalatine ganglion degeneration following subarachnoid hemorrhage induces dry eye.

Background: Head and neck arteriovenous malformations (AVMs) involving branches of the facial nerve often cause tremendous cosmetic, functional, and psychological problems that are challenging to treat. We proposed an algorithm to obtain the optimal treatment and esthetic outcome., Methods: Medical records of 24 patients were reviewed between 2002 and 2015. The lesions were classified into 4 types: type 1, involving no more than 2 facial nerve branches, with a maximal diameter of lesion of 5 cm or less (n = 7); type 2, involving no less than 2 facial nerve branches, with a maximal diameter of lesion of greater than 5 cm (type 2a, facial nerve preservation, n = 8; type 2b, facial reanimation, n = 5); and type 3, involving the mastoid segments or the trunk of the facial nerve (n = 4). Treatment efficacy was assessed and facial function was evaluated using the regional House-Brackmann Facial Nerve Grading System., Results: Cure was achieved in 11 (45.8%) patients, and improvement was achieved in 12 (50.0%) patients, with a follow-up of 36.3 ± 32.9 months (range, 12-144 months). There was no significant difference of the regional House-Brackmann Facial Nerve Grading System score before and after treatment (type 1, unchanged; type 2a, P = 0.356; type 2b, P = 0.423; type 3, unchanged). Treatment outcomes were not significantly related to the type of nerve involvement (P = 1.000) and the facial reanimation procedure (P = 1.000)., Conclusions: Surgical excision or ethanol embolization alone is efficient for type 1 AVMs. The optimal approach for type 2a AVMs was surgery, followed by well-vascularized tissue transfer. In type 2b AVMs, the satisfied treatment results are achieved by lesion excision and immediate facial reanimation. A 2-stage strategy may result in contented treatment outcome in type 3 AVMs.

Objectives: To describe a case of the rare complication of facial palsy following preoperative embolization of a juvenile nasopharyngeal angiofibroma (JNA). To illustrate the vascular supply to the facial nerve and as a result, highlight the etiology of the facial nerve palsy., Methods: The angiography and magnetic resonance (MR) imaging of a case of facial palsy following preoperative embolization of a JNA is reviewed., Results: A 13-year-old male developed left-sided facial palsy following preoperative embolization of a left-sided JNA. Evaluation of MR imaging studies and retrospective review of the angiographic data suggested errant embolization of particles into the petrosquamosal branch of the middle meningeal artery (MMA), a branch of the internal maxillary artery (IMA), through collateral vasculature. The petrosquamosal branch of the MMA is the predominant blood supply to the facial nerve in the facial canal. The facial palsy resolved since complete infarction of the nerve was likely prevented by collateral blood supply from the stylomastoid artery., Conclusions: Facial palsy is a potential complication of embolization of the IMA, a branch of the external carotid artery (ECA). This is secondary to ischemia of the facial nerve due to embolization of its vascular supply. Clinicians should be aware of this potential complication and counsel patients accordingly prior to embolization for JNA.

Background: Microvascular decompression (MVD) is the most effective treatment for hemifacial spasm (HFS). During MVD surgery, abnormal muscle response (AMR) is widely used. Z-L response (ZLR) is a new monitoring method for HFS. We compared the effectiveness of AMR plus ZLR and simple AMR., Methods: In a retrospective study of 1868 cases of HFS treated using intraoperative monitoring between January 2013 and December 2015, 896 patients underwent simple AMR monitoring and 972 underwent combined intraoperative monitoring of AMR and ZLR., Results: AMR waveforms were observed in 837 (93.42%) patients in the AMR group and in 898 (92.39%) patients in the AMR plus ZLR group (P > 0.05). During MVD, AMR waveforms disappeared in 772 patients in the AMR group and 854 patients in the AMR plus ZLR group (P < 0.05). The efficacy rate of MVD in the AMR plus ZLR group was higher compared with the AMR group when AMR was not detected or disappeared during the operation (P < 0.05). When AMR persisted during the operation, there was no significant difference between the 2 groups in efficacy of the operation (P > 0.05)., Conclusions: Regardless of whether the compression vessels of the facial nerve are simple or complicated, combined intraoperative monitoring of AMR plus ZLR monitoring provides more valuable neurosurgical guidance than simple AMR during MVD for HFS., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background & Objective: The effect of direct application of local lidocaine with epinephrine on the facial nerve (FN) has not been reported. The aim of this study is to assess the effects of 2% lidocaine with 1:100,000 epinephrine at clinically relevant concentrations in a rat FN model with respect to facial nerve blood flow (FNBF) and subsequent electrophysiological changes., Materials and Methods: To assess the influence of drugs on FNBF and electrically evoked muscle action potential (EMAP), small pieces of gelfoam were soaked in PBS 100μl (n=5, control group), 50μl (n=5, treatment group A) and 100μl (n=5, group B) of 2% lidocaine with 1:100,000 epinephrine, and 50μl (n=5, group C) and 100μl (n=5, group D) of 2% lidocaine. After 5min of stable recordings, we applied a 2% lidocaine with or without 1:100,000 epinephrine impregnated gelfoam over the main trunk of the facial nerve of rats for 30min. After removing the applied gelfoam, FNBF and threshold of EMAP were measured separately in each group., Results: Compared to the control group, the treatment groups showed a significant reduction in FNBF in a dose-dependent manner. The maximal reductions in FNBF were observed in all treatment groups for a period after 10min of the application. Synergistic reduction in FNBF was greater in groups A and B than in the lidocaine applied groups (C and D). The maximal increase in the EMAP threshold was observed immediately after the respective drug application in all groups. The greatest increase in the EMAP threshold was observed in group B. The increased EMAP threshold returned to the baseline value within 120min in groups A and C., Conclusion: From these results, it can be considered that the topical application of lidocaine with epinephrine caused reduction in FNBF and elevation of EMAP threshold. These acute reductions in FNBF and elevations in the EMAP threshold were restored in a time-dependent manner., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: In hemifacial spasm, it is extremely rare to find a vessel passing through the facial nerve. In this study, we present our experience of the surgical treatment of four such patients., Methods: From January 2010 to Match 2015, we treated 2,576 hemifacial spasm patients with microvascular decompression in our department. Of these, four had an intraneural vessel. Intraoperative findings and treatment were recorded, and postoperative outcomes were analyzed., Results: In three patients, the intraneural vessel was the anterior inferior cerebellar artery, which we wrapped with small pieces of wet gelatin and Teflon sponge. A small vein found in the fourth patient was treated with facial nerve combing. Complete decompression was achieved and abnormal muscle response disappeared. Three patients got an excellent result and one patient got a good result. One patient had postoperative facial paralysis, which improved over 10 months of follow-up., Conclusion: If an artery passes through the facial nerve, it can be decompressed by wrapping the vessel with wet gelatin and Teflon sponge. If a vein passes through the facial nerve, combing can be used. Intraoperative abnormal muscle response monitoring is very helpful in achieving complete decompression.

Many studies have demonstrated that ischemia could induce facial nerve (FN) injury. However, there is a lack of a suitable animal model for FN injury study and thus little knowledge is available about the precise mechanism for FN injury. The aims of this study were to establish a reliable FN injury model induced by blocking the petrosal artery and to investigate whether dysfunctional interaction between cyclophilin D (CypD) and mitochondrial permeability transition pore (MPTP) can mediate cell dysfunction in ischemic FN injury. The outcomes of ischemia-induced FN injury rat model were evaluated by behavioral assessment, histological observation, electrophysiology, and electron microscopy. Then the levels of CypD and protein that forms the MPTP were evaluated under the conditions with or without the treatment of Cyclosporin A (CsA), which has been found to disrupt MPTP through the binding of CypD. The blocking of petrosal artery caused significant facial palsy signs in the ischemia group but not in the sham group. Furthermore, ischemia can induce the dysfunction of facial nucleus neurons and destruction of the myelin sheath and increase the protein levels of CypD and MPTP protein compared with sham group. Interestingly, treatment with CsA significantly improved neurological function and reversed the ischemia-induced increase of CypD and MPTP proteins in ischemia group. These results demonstrated that blocking of petrosal artery in rats can induce FN injury and the mechanism may be related to the disruption of MPTP by CypD.

Head and neck cancer is often diagnosed at advanced stages, and surgical resection with wide margins is generally indicated, despite this treatment being associated with poor postoperative quality of life (QOL). We have previously reported on the therapeutic effects of skeletal muscle-derived multipotent stem cells (Sk-MSCs), which exert reconstitution capacity for muscle-nerve-blood vessel units. Recently, we further developed a 3D patch-transplantation system using Sk-MSC sheet-pellets. The aim of this study is the application of the 3D Sk-MSC transplantation system to the reconstitution of facial complex nerve-vascular networks after severe damage. Mouse experiments were performed for histological analysis and rats were used for functional examinations. The Sk-MSC sheet-pellets were prepared from GFP-Tg mice and SD rats, and were transplanted into the facial resection model (ST). Culture medium was transplanted as a control (NT). In the mouse experiment, facial-nerve-palsy (FNP) scoring was performed weekly during the recovery period, and immunohistochemistry was used for the evaluation of histological recovery after 8 weeks. In rats, contractility of facial muscles was measured via electrical stimulation of facial nerves root, as the marker of total functional recovery at 8 weeks after transplantation. The ST-group showed significantly higher FNP (about three fold) scores when compared to the NT-group after 2-8 weeks. Similarly, significant functional recovery of whisker movement muscles was confirmed in the ST-group at 8 weeks after transplantation. In addition, engrafted GFP+ cells formed complex branches of nerve-vascular networks, with differentiation into Schwann cells and perineurial/endoneurial cells, as well as vascular endothelial and smooth muscle cells. Thus, Sk-MSC sheet-pellet transplantation is potentially useful for functional reconstitution therapy of large defects in facial nerve-vascular networks.

Background and Purpose: A minority of patients who undergo microvascular decompression for hemifacial spasm do not improve after the first operation. We sought to determine the most common locations of unaddressed neurovascular contact in patients with persistent or recurrent hemifacial spasm despite prior microvascular decompression., Materials and Methods: Eighteen patients with a history of a microvascular decompression presented with persistent hemifacial spasm. All patients underwent thin-section steady-state free precession MR imaging. Fourteen patients underwent repeat microvascular decompression at our institution. Images were evaluated for the following: the presence of persistent vascular compression of the facial nerve, type of culprit vessel (artery or vein), name of the culprit artery, segment of the nerve in contact with the vessel, and location of the point of contact relative to the existing surgical pledget. The imaging findings were compared with the operative findings., Results: In 12 of the 18 patients (67%), persistent vascular compression was identified by imaging. In 11 of these 12 patients, the culprit vessel was an artery. Compression of the attached segment (along the ventral surface of the pons) was identified in most patients (58%, 7/12). The point of contact was proximal to the surgical pledget in most patients (83%, 10/12). The imaging interpretation was concordant with the surgical results regarding artery versus vein in 86% of cases and regarding the segment of the nerve contacted in 92%., Conclusions: In patients with persistent hemifacial spasm despite microvascular decompression, the unaddressed vascular compression is typically proximal to the previously placed pledget, usually along the attached segment of the nerve. Re-imaging with high-resolution T2-weighted MR imaging will usually identify the culprit vessel., (© 2015 by American Journal of Neuroradiology.)

Background: The medial zygomaticotemporal vein (MZTV), clinically known as sentinel vein, has been observed in the vicinity of the temporal branch of the facial nerve during endoscopic procedures aiming to lift the upper face. The aim of the present study was to describe the topography of the MZTV with reference to the superficial landmarks for providing detailed anatomical information during injectable treatment procedures., Methods: Eighteen hemifaces were harvested from nine embalmed Korean adult cadavers (5 males and 4 females, mean age 76 years). The piercing location, vascular diameter, drainage pattern of the MZTV, and its relationship with the orbicularis oculi muscle (OOc) were recorded photographically, and using diagrams and written notes., Results: The piercing point of the MZTV was located 26.8 ± 5.9 mm from the lateral epicanthus, 18.8 ± 6.9 mm lateral to the plane (HP) through the tragus and the lateral epicanthus, and 19.0 ± 5.4 mm superior to the plane (VP) through the lateral epicanthus point and perpendicular to the HP. The diameter of the MZTV at the piercing point was 1.9 ± 0.8 mm. All of the MZTV ultimately connected with the middle temporal vein (MTV). In particular, the MZTV was connected the MTV by anastomosing with the periorbital vein. Anastomosis of the MZTV and a well-developed periorbital vein was found in 27.8 % of cases., Conclusion: The physician must determine the location of the MZTV and should be able to accurately estimate its connection with significant veins at the temple to reduce the risk of severe complications during injectable treatments.

Background: The use of vascularized nerve graft models has been limited because of the complexity of the operation. The authors sought to develop a simple and effective rabbit model for facial nerve repair and evaluated its advantages over conventional nerve grafts., Methods: Rabbits were divided into three groups consisting of six rabbits each. The central auricular nerve and its nutrient vessels were used as a vascularized graft. Rabbits were grafted with a vascularized facial nerve graft (vascularized nerve graft group), with a free nerve graft (free nerve graft group), or with a vascularized nerve graft and a free nerve graft on each side of the face (vascularized nerve graft/free nerve graft group). Four months after surgery, facial performance and electrophysiologic monitoring were evaluated. The rabbits were then killed to prepare the nerve specimens for histologic, immunohistochemical, and transmission electron microscope study., Results: At 4 months after the facial nerve repair, the functional recovery of the facial nerve was observed and analyzed. The side grafted with vascularized nerve graft was superior to the side grafted with free nerve graft. Regenerated nerve fibers were observed in all groups, and rabbits grafted with vascularized nerve grafts had more regenerated axons than those that underwent free nerve grafting, although the regenerated nerves were not as good as the natural nerves., Conclusions: This study demonstrates that it is feasible to establish a vascularized nerve graft model in rabbits. The model offers the obvious advantages of operability and reliability. The vascularized nerve graft is demonstrated to have a superior value for facial nerve repair.

Here, we present a case of a 55-year-old woman with a 10-year history of hemifacial spasm accompanied by 1-month ipsilateral paroxysmal otalgia. Magnetic resonance imaging revealed the presence of vessels around the facial nerve root. Surgical exploration via suboccipital retromastoid craniotomy showed converging compression of the facial nerve root and intermediate nerve from both sides by an anterior inferior cerebellar artery loop. The patient's hemifacial spasm and ipsilateral otalgia were completely relieved after microvascular decompression of the facial nerve root and intermediate nerve. Intraoperative findings and the postoperative result of this case confirmed that vascular compression of the intermediate nerve was the exclusive cause of paroxysmal otalgia. The presence of ipsilateral hemifacial spasm, combined with preoperative neuroimaging studies, contributed to the diagnosis of intermediate nerve neuralgia. Microvascular decompression should be considered for the management of patients with intermediate nerve neuralgia.

Objective: To produce a high-resolution, three-dimensional temporal bone model from serial sections, using a personal computer., Method: Digital images were acquired from histological sections of the temporal bone. Image registration, segmentation and three-dimensional volumetric reconstruction were performed using a personal computer. The model was assessed for anatomical accuracy and interactivity by otologists., Results: An accurate, high-resolution, three-dimensional model of the temporal bone was produced, containing structures relevant to otological surgery. The facial nerve, labyrinth, internal carotid artery, jugular bulb and all of the ossicles were seen (including the stapes footplate), together with the internal and external auditory meati. Some projections also showed the chorda tympani nerve., Conclusion: A high-resolution, three-dimensional computer model of the complete temporal bone was produced using a personal computer. Because of the increasing difficulty in procuring cadaveric bones, this model could be a useful adjunct for training.

Introduction: The facial nerve follows a complex course through the skull base. Understanding its anatomy is crucial during standard skull base approaches and resection of certain skull base tumors closely related to the nerve, especially, tumors at the cerebellopontine angle., Methods: Herein, we review the fallopian canal and its implications in surgical approaches to the skull base. Furthermore, we suggest a new classification., Conclusions: Based on the anatomy and literature, we propose that the meatal segment of the facial nerve be included as a component of the fallopian canal. A comprehensive knowledge of the course of the facial nerve is important to those who treat patients with pathology of or near this cranial nerve.

Hemifacial spasm (HFS) is characterized by involuntary unilateral contractions of the muscles innervated by the ipsilateral facial nerve, usually starting around the eyes before progressing inferiorly to the cheek, mouth, and neck. Its prevalence is 9.8 per 100,000 persons with an average age of onset of 44 years. The accepted pathophysiology of HFS suggests that it is a disease process of the nerve root entry zone of the facial nerve. HFS can be divided into two types: primary and secondary. Primary HFS is triggered by vascular compression whereas secondary HFS comprises all other causes of facial nerve damage. Clinical examination and imaging modalities such as electromyography (EMG) and magnetic resonance imaging (MRI) are useful to differentiate HFS from other facial movement disorders and for intraoperative planning. The standard medical management for HFS is botulinum neurotoxin (BoNT) injections, which provides low-risk but limited symptomatic relief. The only curative treatment for HFS is microvascular decompression (MVD), a surgical intervention that provides lasting symptomatic relief by reducing compression of the facial nerve root. With a low rate of complications such as hearing loss, MVD remains the treatment of choice for HFS patients as intraoperative technique and monitoring continue to improve.

Objective: To explore the operative guiding values of facial nerve three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) and three-dimensional fast imaging employing steady state acquisition three-dimensional fast imaging employing steady state acquisition (3D-FIESTA) scan., Methods: A total of 125 cases of primary hemifacial spasm was treated at our hospital from 2004 to 2012. Among them, 80 cases received preoperative facial nerve MRA scan. The imaging and intraoperative findings were compared to determine the responsible blood vessels., Results: Responsible blood vessels were found in all 80 cases. Sixty patients (75%) had the involvement of single vessel of anterior inferior cerebellar artery (AICA, n = 57), posterior inferior cerebellar artery (PICA, n = 1), superior cerebellar artery (SCA, n = 1) and vertebral artery (VA, n = 1). Two or more vessels were implicated in 9 patients (11.25%). The culprits were AICA+ internal auditory artery (n = 8) and PICA+ internal auditory artery (n = 1). The source of responsible vessels of 11 cases could not be determined before surgery. Through intraoperative anatomy, 59 patients had single vessel lesions, including AICA (n = 53), PICA (n = 4), SCA (n = 1) and VA (n = 1). Among 14 cases of multiple vessels, there were AICA + internal auditory artery (n = 7), internal auditory artery + PICA (n = 2), AICA + brain stem perforating artery (n = 3) and AICA + vein (n = 2). Seven cases were uncertain. No significant statistical difference existed between two groups., Conclusion: Facial nerve 3D-TOF-MRA and 3D-FIESTA scan can identify the status of responsible blood vessels to guide operations.

The objective of this study is to investigate late repeat microvascular decompression (MVD) with persistent or recurrent hemifacial spasm (HFS) and to compare the clinical characteristics, intraoperative findings, complications, and outcomes with first MVD. We analyzed MVDs performed at the University of Pittsburgh Medical Center between January 1, 2000 and December 31, 2007. Thirty-three patients who underwent late redo MVDs were classified as group I and 243 patients who underwent their first MVD as group II. Clinical data were collected to analyze the difference between the two groups. The mean follow-up period was 54.48 months (range, 9-102 months). There is no significant difference in preoperative clinical characteristics (gender, age, side of MVD, botox usage, facial weakness) between the two groups. In present study, we found a vein as the offending vessel in significantly more number of patients who underwent repeat MVD as compared to first MVD (P = 0.02). The lateral spread response disappeared in 66% of patients during repeat MVDs, which is not different from those undergoing their first MVD. No difference in the relief rate was found during the immediate postoperative, discharge, or follow-up stages between repeat and first MVD. Moreover, no difference was found in the incidence of complications between repeat MVD and first MVD. Late repeat MVD for HFS is an effective and safe procedure. No specific preoperative clinical characteristics were identified in patients with repeat MVD. Intraoperative monitoring with lateral spread response (LSR) is an effective tool to evaluate adequate decompression. In patients with persistent LSR at the end of the procedure, facial nerve compression from a vein should be examined. We believe that it is important to undergo a repeat MVD for failed HFS relief irrespective of the timing of the operation.

Object: The root exit zone (RExZ) of the facial nerve has been considered to be the target in microvascular decompression (MVD) for hemifacial spasm. However, more proximal segments with oligodendrocyte-derived myelin, where the facial nerve root emerges at the pontomedullary sulcus and adheres to the brainstem surface (root emerging zone [REmZ]), may also be susceptible to neurovascular compression. This study evaluated the predictive value of magnetic resonance (MR) imaging in detecting and assessing the features of vascular compression, especially in the pontomedullary sulcus, and describes the technical considerations of MVD procedures for the more proximal segments of the facial nerve., Methods: Twenty patients treated with MVD underwent three-dimensional constructive interference in steady-state MR imaging and three-dimensional time-of-flight MR angiography. Their fusion images were used to evaluate the anatomical neurovascular relationships and intraoperative findings were analyzed., Results: Most offending arteries at the REmZ and the RExZ of the facial nerve were correctly identified by fusion MR imaging. During surgery, neurovascular contacts were identified at one or more segments of the facial nerve in all patients. The REmZ of the facial nerve was affected in 55 % of the patients. The most common offending vessel at the REmZ was the posterior inferior cerebellar artery rather than the anterior inferior cerebellar artery. The key procedure to explore the deep-seated REmZ in the pontomedullary sulcus was full dissection of the lower cranial nerves to the brainstem origin., Conclusions: Our definition more correctly describes the specific anatomical relationship of the facial nerve origin from the brainstem and the clinically relevant target for MVD surgery. Fusion MR imaging is very useful to identify neurovascular contacts at both the RExZ and the REmZ of the facial nerve.

Objective: This retrospective study is to explore the clinical features and surgical outcomes of the patients who suffered from hemifacial spasm preceded by Bell's palsy., Methods: Seventeen patients with post-Bell's palsy hemifacial spasm underwent microvascular decompression surgery. A 3D-TOF-MRA examination was performed pre-operatively to confirm the existence of offending vessels around the facial nerve. Abnormal muscle response was monitored during operation. The results of spasm resolution and post-operative complications were assessed., Results: During operation, offending vessels were found and transposed in 15 patients. For the other two patients in whom offending vessel was absent, the facial nerve was treated by combing. The results of spasm resolution were 'cured' in 12 (70·5%) patients, 'improved' in 2 (11·8%) patients, 'fair' in 2 (11·8%) patient, and 'failed' in 1 (5·9%) patient. The complications included transient hearing loss in one case, and deterioration of facial weakness in two cases., Conclusion: Vascular compression may be an etiological factor of post-Bell's palsy hemifacial spasm, and microvascular decompression is an effective treatment to this disorder.

Ischemic stroke affects over 15 million patients per year and is a leading cause of death worldwide. Currently available treatments are indicated for less than 5% of patients. Stimulation of the facial nerve has been proposed as a possible new treatment of ischemic stroke that acts by increasing blood flow to the brain and thereby restoring perfusion through collateral vessels. The objective of this project was to evaluate the changes in brain perfusion, following facial nerve stimulation in an animal stroke model using MRI measures of cerebral blood flow. Autologous blood clot was injected in the internal carotid artery to occlude the middle cerebral artery (MCA) in 17 mongrel dogs. Occlusion in the MCA was verified using fluoroscopy and MRI angiography. Following baseline and post-stroke MRI images, the facial nerve at the site of the geniculate ganglion was located and then stimulated using a transcranial magnetic stimulator and a neuro-navigation system in 11 animals. Six animals followed the same procedure but were not stimulated (control group). The perfusion index of both sides of the brain was measured using gadolinium contrast MRI before and after stroke, and at 30 minute intervals after stimulation. Results show a significant and persistent increase in perfusion in the stroke side of the brain relative to the non-stroke / contralateral side, after stimulation, when compared to the control group. These results strongly support the future development and evaluation of a non-invasive facial nerve stimulator device for the early treatment of ischemic stroke.

The case history is described of a patient referred to our institution with facial nerve palsy following embolization of a middle cranial fossa dural arteriovenous fistula using ethylene vinyl alcohol copolymer (EVOH). Facial nerve decompression was performed which showed evidence of extensive penetration of EVOH into the vasa nervosa of the facial nerve. Facial nerve palsy is a debilitating complication that can be avoided by attention to the lower cranial nerve arterial supply during careful procedural planning and consideration of alternative strategies for fistula obliteration in cases where eloquent feeders are involved.

Given the length of axons reaching to distal regions, all peripheral nerves must derive nutrient supply not only for the nerve cell body, but also for the peripheral parts. Along the course of a peripheral nerve, in general, nutrient vessels accompany nerve fibers to peripheral regions in the form of "vasa nervorum" derived from the epineurium, reaching the endoneurium through the perineurium and forming a capillary plexus. In addition, in reconstructive procedures in plastic surgery, anastomosis of not only nerves, but also the vasa nervorum, has been reported to achieve improved outcomes. The present study therefore observed morphological features of the blood supply to the distal portion of the facial nerve in 14 sides of 14 adult cadavers (age at death, 46-86 years) under stereo microscopy after dye injection. The region of the epineurium was also observed under scanning electron microscopy (SEM). The vasa nervorum was seen to derive from a complex reticulation structure formed mainly by the superficial temporal, facial, transverse facial and zygomatico-orbital arteries with collateral supply from the supraorbital, deep temporal, buccal arteries and parotid branches. SEM showed that one capillary accompanied each perineurium in each nerve fascicle.

Aim: To demonstrate the enhanced radiological anatomy and common pathological conditions of the facial nerve by using magnetic resonance imaging (MRI)., Materials and Methods: A retrospective review of the MRI findings of the facial nerve of 146 patients who visited a tertiary academic referral center was conducted., Results: The radiological anatomy of the facial nerve was well illustrated using MRI, as were most of the common pathological conditions of the facial nerve., Conclusions: Enhancement of the facial nerve in MRI should be correlated with the clinical data. Normal individuals can show enhancement of the tympanic or vertical segments of the facial nerve. Enhancement of the labyrinthine portion of the nerve is almost diagnostic of Bell's palsy. No specific enhancement patterns were observed for tumours or for infections of the middle or external ear. A larger population study is required for the accurate assessment of facial nerve enhancement in multiple sclerosis patients., (Copyright © 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Background: Preservation of facial nerve function is one of the most important goals in acoustic neuroma surgery. We have been using intraoperative continuous monitoring of evoked facial nerve electromyograms (EMGs) since 1997 in acoustic neuroma surgery. We therefore investigated surgically treated patients to clarify the usefulness of this monitoring, and to determine safety criteria for preserving facial nerve function., Methods: This intraoperative continuous monitoring of evoked facial nerve EMG is a method for checking the EMG evoked by continuous direct electrical stimulation of the facial nerve during tumor excision. The greatest advantage of this method is the ability to identify changes in EMG in real time. We retrospectively investigated 216 patients with surgically treated acoustic neuroma to identify correlations between parameters in this monitoring and postoperative facial nerve function immediately and 1 year after surgery., Results: In these patients, the functional preservation rate of the facial nerve (House and Brackmann grade 1 or 2 at 1 year after surgery) was 98.6% with a 98.2% mean tumor resection rate. Amplitude preservation ratio correlated significantly with facial nerve function both immediately and 1 year after surgery. To avoid severe facial nerve palsy, a warning criterion of amplitude preservation ratio >50% appears useful., Conclusions: Postoperative course of facial nerve function appears predictable using intraoperative continuous monitoring of evoked facial nerve EMGs. This monitoring is useful to increase the tumor excision rate while avoiding severe postoperative facial nerve palsy in acoustic neuroma surgery.

An enlarged facial nerve canal can be a seen in both pathologic and nonpathologic processes. The purposes of this report are the following: 1) to present a rare cause of bony facial nerve canal enlargement, due to an enlarged vein, with high-resolution MDCT and histopathologic correlation; and 2) to discuss the vascular anatomy that gives rise to this variant.

Purpose: To investigate the feasibility of repairing whole facial nerve defects with chemically extracted acellular whole facial allografts nerves and its effect on motor conductivity recovery., Materials and Methods: Whole nerve defects (branches and trunk) were made in 4 rabbit groups (n = 18), and the nerve defect was bridged using 1) acellular facial nerve allografts, 2) facial nerve isografts, 3) acellular peroneal nerve allografts, and 4) peroneal nerve isografts. Six months later, cell morphology, nerve microbeam distribution, angiogenesis, and collagen were observed in the distal and center of the grafts with special trichrome staining. The regenerated nerve fibers and Schwann cells in the anastomosis site were immunohistochemically stained. Nerve axon numbers and passing rates were analyzed with computer-captured images. The regenerated nerve ultrastructure was analyzed by transmission electron microscopy., Results: Regenerated nerve fibers and vessels were found in the grafts, with no differences between groups A and B. Groups C and D had poor nerve continuity with little vascular regeneration. The distal segments of nerve transplants in groups A and B showed strong positive neurofilament staining, higher than in groups C and D. In groups A and B, many long spindle-shaped Schwann cells proliferated longitudinally in the nerve transplant, but less in groups C and D. Myelinated nerve fibers were found in the distal facial nerve. There were no differences between groups A and B in fiber number and myelin sheath thickness, which were much lower than normal, whereas little myelin sheath regeneration was observed in groups C and D., Conclusion: Chemically extracted acellular whole facial nerve allografts are feasible for repairing whole facial nerve defects., (Copyright 2010 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Möbius sequence is a rare congenital disorder defined by partial or complete agenesis of the 6th and 7th cranial nerves, which control eye movement and facial expression. The etiology is unclear but genetic and teratogenic factors are thought to be involved. Ischemia affecting the cranial nerve nuclei is a possible pathomechanism of Möbius sequence. Most cases of Möbius sequence are sporadic but some familial cases are also known. The inheritance patterns of Möbius sequence are heterogeneous and can be autosomal recessive, autosomal dominant or even X-linked. Some candidate regions and candidate genes have been described but no causative gene has yet been confirmed.

In the cerebellopontine angle cistern, the nervus intermedius (NI) runs close to the motor division of the facial nerve (FN). A vascular loop compressing the FN in patients with hemifacial spasm (HFS) can thus also affect the NI. However, to our knowledge, taste has not been investigated in patients with HFS. In this pilot study, we assessed the sense of taste quantitatively in 10 female patients with HFS using filter paper strips impregnated with four taste qualities (sweet, sour, salty, and bitter) at four concentrations. The taste score did not differ between the ipsilateral and contralateral sides. The taste score for salty on the ipsilateral side increased with disease duration. Our findings suggest that a vascular loop compressing the FN does not affect the function of the NI. Further studies with greater numbers of patients are needed to confirm our results.

Background and Purpose: The purpose of this article is to assess the validity of the magnetic resonance imaging (MRI) CISS 3D sequence associated with 3D time of flight (TOF) angiographic sequence in order to detect neurovascular contact (NVC) between the facial nerve and neighbouring arteries in patients with essential hemifacial spasm (HFS) and to determine the relationship between HFS symptoms and NVC and NVC image features (type, number and site)., Materials and Methods: We prospectively enrolled 120 cerebellopontine angle (CPA) MRI studies, 44 cases with HFS symptoms and 76 which were asymptomatic (controls), using axial T2-weighted (CISS) and axial 3D TOF series with associated Maximal intensity (MIP) reconstructions. Prior TOF angiographic studies were available for 56 cases without associated CISS images and the results obtained from that study were compared with the results of the current study., Results: The diagnostic values obtained significantly favoured the protocol used in this study, which demonstrated a sensitivity of 77.27% and a specificity of 75%. There was a statistically significant relationship between the presence of NVC and HFS symptoms (p<0.0001). Only one statistically significant relationship was found between facial nerve displacement (in type of NVC) and HFS symptoms (p=0.019)., Conclusions: The proposed MRI protocol is sensitive and valid for detecting NVC in patients with HFS. The results of our study support a relationship between NVC and HFS symptoms. It is not a simple relationship, however. It may be influenced by other factors, such as displacement of the facial nerve due to NVC.

Object: In this paper, the authors' goal was to determine the utility of monitoring the abnormal muscle response (AMR) or "lateral spread" during microvascular decompression surgery for hemifacial spasm., Methods: The authors' experience with AMR as well as the data available in the English-language literature regarding resolution or persistence of AMR and the resolution or persistence of hemifacial spasm at follow-up was pooled and subjected to a meta-analysis., Results: The pooled OR revealed by the meta-analysis was 4.2 (95% CI 2.7-6.7). The chance of a cure if the AMR was abolished during surgery was 4.2 times greater than if the lateral spread persisted., Conclusions: The AMR should be monitored routinely in the operating room, and surgical decision-making in the operating room should be augmented by the AMR.

The article describes our results of surgical treatment of 37 patients with hemifacial spasm (HS) as well as results of morphological studies of facial nerve root exit zone (REZ). Morphological studies demonstrated that extension of central myelinated zone differed between 0.9 and 3.6 mm (mean 2.24 mm). This zone did not exceed 1.1 diameter of facial nerve. Intraoperative findings included 27 cases of compression by a single vessel and 9 cases of compression by multiple vessels. In cases of compression by a single vessel the offending artery was AICA in 11 cases, PICA in 12 cases and VA in 4 cases. In 35 patients complete decompression of facial nerve REZ was achieved. In one case complete decompression was not possible due to penetration o vestibular nerve by AICA which prevented safe manipulations of the artery and nerves. Excellent results of surgical treatment were achieved in 33 patients. In 1 described case the outcome was unsatisfactory. We observed no serious postoperative complications. Vascular decompression is highly effective and relatively safe procedure for treatment o HS. HS results from compression of central myelinated zone of facial nerve thus surgical decompression should be preformed close to REZ at the brainstem.

Background: The identification of the facial nerve can be difficult in a bloody operative field or by an incision that limits exposure; hence anatomical landmarks and adequate operative exposure can aid such identification and preservation. In this clinico-anatomic study, we examined the stylomastoid artery (SMA) and its relation to the facial nerve trunk; the origin of the artery was identified on cadavers and its nature was confirmed histologically., Methods: The clinical component of the study included prospective reviewing of 100 consecutive routine parotidectomies; while, the anatomical component of the study involved dissecting 50 cadaveric hemifaces., Results: We could consistently identify a supplying vessel, stylomastoid artery, which tends to vary less in position than the facial nerve. Following this vessel, a few millimetres inferiorly and medially, we have gone on to identify the facial nerve trunk, which it supplies, with relative ease. The origin of the stylomastoid artery, in our study, was either from the occipital artery or the posterior auricular artery., Conclusion: This anatomical aid, the stylomastoid artery, when supplemented by the other more commonly known anatomical landmarks and intra-operative facial nerve monitoring further reduces the risk of iatrogenic facial nerve damage and operative time.

Objective: To identify pathological changes to vessels in the facial nerve canal among patients with diabetes mellitus., Design: Histopathologic human temporal bone study., Subject: This study examined 26 temporal bones from 13 patients with type 1 diabetes mellitus and 40 temporal bones from 20 patients with type 2 diabetes mellitus. Temporal bones from patients with type 2 diabetes mellitus were divided into 2 groups according to the method of diabetes management: insulin (n = 11) and oral hypoglycemic agents (n = 9). For the control groups, 16 age-matched normal temporal bones from 11 subjects were recruited for type 1 diabetes mellitus and 11 age-matched normal temporal bones from 8 subjects were recruited for type 2 diabetes mellitus., Main Outcome Measures: Thicknesses of vessel walls in the labyrinthine, tympanic, and mastoid portions of the facial nerve canal were examined under light microscopy., Results: Vessel walls for all portions of the facial nerve canal were significantly thicker in diabetic patients than in normal controls for both types 1 and 2 diabetes. In type 2 diabetic patients, vessel wall thickness was significantly greater in patients treated with insulin therapy than in patients treated via oral hypoglycemic agents., Conclusion: The facial nerve in patients with diabetes mellitus is ischemic compared with normal controls. These findings suggest a histologic basis for the high incidence and difficulty in achieving improvement of facial nerve palsy in patients with diabetes mellitus.

Introduction: The aim of our study was to establish a systematization of collateral branches originating from posterior auricular artery to facial nerve in prestylian space., Materials and Methods: Thirty posterior auricular arteries were studied on 15 fresh cadavers after selective patent blue injection. We observed subsequent colouration of facial nerve. Number and topography of collateral branches were highlighted., Results: Posterior auricular artery supplied facial nerve in 67%. Collateral branches dedicated to facial nerve could be classified into three types: type 1 corresponded to one artery in prestylian space, type 2 to several branches in prestylian space; finally type 3 featured several branches originating from posterior auricular artery in prestylian space on the one hand, in superficial retroauricular area on the other hand., Conclusion: Posterior auricular artery is the main blood supply to facial nerve in prestylian space. In most of the cases, branches to facial nerve originate deeply in parotid space. Nevertheless nervous branches may originate from superficial retroauricular segment of posterior auricular artery. Their damage during surgical procedures as bat ear surgery can cause definitive facial nerve palsy.

Object: It is generally accepted that hemifacial spasm (HFS) is caused by pulsatile vascular compression upon the facial nerve root exit zone. This 2-3 mm area, considered synonymous with the Obersteiner-Redlich zone, is a transition zone (TZ) between central and peripheral axonal myelination that is situated at the nerve's detachment from the pons. Further proximally, however, the facial nerve is exposed on the pontine surface and emerges from the pontomedullary sulcus. The incidence and significance of neurovascular compression upon these different segments of the facial nerve in patients with HFS has not been previously reported., Methods: The nature of neurovascular compression was determined in 115 consecutive patients undergoing their first microvascular decompression (MVD) for HFS. The location of neurovascular compression was categorized to 1 of 4 anatomical portions of the facial nerve: RExP = root exit point; AS = attached segment; RDP = root detachment point that corresponds to the TZ; and CP = distal cisternal portion. The severity of compression was defined as follows: mild = contact without indentation of nerve; moderate = indentation; and severe = deviation of the nerve course. Success in alleviating HFS was documented by telephone interview conducted at least 24 months following MVD surgery., Results: Neurovascular compression was found in all patients, and the main culprit was the anterior inferior cerebellar artery (in 43%), posterior inferior cerebellar artery (in 31%), vertebral artery (in 23%), or a large vein (in 3%). Multiple compressing vessels were found in 38% of cases. The primary culprit location was at RExP in 10%, AS in 64%, RDP in 22%, and CP in 3%. The severity of compression was mild in 27%, moderate in 61%, and severe in 12%. Failure to alleviate HFS occurred in 9 cases, and was not related to compression location, severity, or vessel type., Conclusions: The authors observed that culprit neurovascular compression was present in all cases of HFS, but situated at the RDP or Obersteiner-Redlich zone in only one-quarter of cases and rarely on the more distal facial nerve root. Since the majority of culprit compression was found more proximally on the pontine surface or even pontomedullary sulcus origin of the facial nerve, these areas must be effectively visualized to achieve consistent success in performing MVD for HFS.

Objective: The protective effect of edaravone, an inhibitor of reactive oxygen species (ROS), against the development of ischemia-induced facial palsy was investigated., Methods: Experimental ischemic facial palsy was induced by interruption of the petrosal artery (PA) in guinea pigs. The application of edaravone was carried out by daily intraperitoneal injection for 1 week. The behavioral facial movement, fluorescence intensity of ROS, and morphological changes were investigated., Results: Edaravone injection from immediately after PA interruption significantly reduced dihydrotetramethylrosamine fluorescence intensity (indicative of ROS) in the facial nerve of the interrupted ear and attenuated the development of ischemia-induced facial palsy. Edaravone injection from the 2nd day following PA interruption also reduced the incidence of facial palsy. Light and electron microscopy revealed that edaravone application tended to prevent the degenerative changes of the facial nerve caused by ischemia., Conclusions: Edaravone suppressed the production of ROS and had a remarkable protective effect against the development of mild to moderate facial palsy. Morphologically, nerve damage was also decreased by edaravone injection.

Object: Microvascular decompression (MVD) of the facial nerve is an effective treatment for hemifacial spasm (HFS), but the procedure is associated with a significant risk of complications such as hearing loss and facial weakness. Many surgeons advocate the use of intraoperative brainstem auditory evoked response (BAER) monitoring in an attempt to improve surgical outcomes. The authors critically assessed a large series of patients with HFS who underwent MVD without neurophysiological monitoring., Methods: The authors retrospectively identified 114 consecutive patients, with a history of HFS and without a history of HFS surgery, in whom MVD was performed by a single surgeon without the use of neurophysiological monitoring. Postoperative outcomes were determined by reviewing records and through telephone interviews. At least 1 year of postoperative follow-up data were available for 91 of the 114 patients, and the median follow-up duration in all cases was 8 years (range 3 months-23 years). A Kaplan-Meier analysis showed that 86% of the patients were spasm free at 10 years postoperatively., Results: There were no surgical deaths or major deficits, and complications included 1 case of postoperative deafness, 1 of permanent subtotal hearing loss, and 10 of delayed facial palsy, 2 of which did not completely resolve at last follow-up. The outcomes, rates of hearing loss, and other complications compared well with those reported in studies in which investigators used intraoperative monitoring., Conclusions: The results suggest that MVD without neurophysiological monitoring is a safe and effective treatment option in patients with HFS. Although BAER monitoring may be a valuable adjunct to surgery at centers experienced with the modality, the absence of intraoperative monitoring should not prevent neurosurgeons from performing MVD in patients with HFS.