The petrosal artery and its variations: a comprehensive review and anatomical study with application to skull base surgery and neurointerventional procedures.

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.

Surgical Anatomy of the Labyrinthine and Subarcuate Arteries and Clinical Implications.

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.

Facial Nerve Branching Patterns Vary With Vascular Anomalies.

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.

Transposition of the Culprit Artery Passing Between the Facial Nerve and Auditory Nerve in Microvascular Decompression Surgery for Hemifacial Spasm.

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.

Endoscopic Transcanal Approach to Geniculate Ganglion Hemangioma and Simultaneous Facial Nerve Reinnervation: A Case Report.

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.

Microcirculation evaluation of facial nerve palsy using laser speckle contrast imaging: a prospective study.

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.

Treatment of Head and Neck Arteriovenous Malformations Involving the Facial Nerve: A Tailored Algorithm.

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.

Facial Palsy Following Embolization of a Juvenile Nasopharyngeal Angiofibroma.

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.

The Effects of Combined Intraoperative Monitoring of Abnormal Muscle Response and Z-L Response for Hemifacial Spasm.

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.

Management of vessels passing through the facial nerve in the treatment of hemifacial spasm.

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.

Reconstruction of Multiple Facial Nerve Branches Using Skeletal Muscle-Derived Multipotent Stem Cell Sheet-Pellet Transplantation.

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.

Vascularized versus nonvascularized facial nerve grafts using a new rabbit model.

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.

MRI findings in patients with a history of failed prior microvascular decompression for hemifacial spasm: how to image and where to look.

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.

Intermediate nerve neuralgia can be diagnosed and cured by microvascular decompression.

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.

Three-dimensional temporal bone reconstruction from histological sections.

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.

The fallopian canal: a comprehensive review and proposal of a new classification.

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.

Microvascular decompression for hemifacial spasm: focus on late reoperation.

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.

Microvascular decompression of the root emerging zone for hemifacial spasm: evaluation by fusion magnetic resonance imaging and technical considerations.

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.

Microvascular decompression treatment for post-Bell's palsy hemifacial spasm.

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.

[Guiding values of facial nerve 3D-TOF-MRA and 3D-FIESTA scan for primary hemifacial spasm operation].

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.