Structural remodeling in related brain regions in patients with facial synkinesis

Facial synkinesis is a troublesome sequelae of facial nerve malfunction. It is difficult to recover from synkinesis, despite improved surgical techniques for isolating the peripheral facial nerve branches. Furthermore, it remains unclear whether long-term dysfunction of motor control can lead to irreversible plasticity-induced structural brain changes. This case-control study thus investigated the structural brain alterations associated with facial synkinesis. The study was conducted at Shanghai Ninth People''s Hospital, Shanghai Jiao Tong University School of Medicine, China. Twenty patients with facial synkinesis (2 male and 18 female, aged 33.35 ± 6.97 years) and 19 healthy volunteers (2 male and 17 female, aged 33.21 ± 6.75 years) underwent magnetic resonance imaging, and voxel-based and surface-based morphometry techniques were used to analyze data. There was no significant difference in brain volume between patients with facial synkinesis and healthy volunteers. Patients with facial synkinesis exhibited a significantly reduced cortical thickness in the contralateral superior and inferior temporal gyri and a reduced sulcal depth of the ipsilateral precuneus compared with healthy volunteers. In addition, sulcal depth of the ipsilateral precuneus was negatively correlated with the severity of depression. These findings suggest that there is a structural remodeling of gray matter in patients with facial synkinesis after facial nerve malfunction. This study was approved by the Ethics Review Committee of the Ninth People''s Hospital, Shanghai Jiao Tong University School of Medicine, China (approval No. 2017-365-T267) on September 13, 2017, and was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR1800014630) on January 25, 2018.     

Chitin scaffold combined with autologous small nerve repairs sciatic nerve defects

Although autologous nerve transplantation is the gold standard for treating peripheral nerve defects,it has many clinical limitations.As an alternative,various tissue-engineered nerve grafts have been developed to substitute for autologous nerves.In this study,a novel nerve graft composed of chitin scaffolds and a small autologous nerve was used to repair sciatic nerve defects in rats.The novel nerve graft greatly facilitated regeneration of the sciatic nerve and myelin sheath,reduced atrophy of the target muscle,and effectively restored neurological function.When the epineurium of the small autogenous nerve was removed,the degree of nerve regeneration was similar to that which occurs after autogenous nerve transplantation.These findings suggest that our novel nerve graft might eventually be a new option for the construction of tissue-engineered nerve scaffolds.The study was approved by the Research Ethics Committee of Peking University People's Hospital(approval No.2019 PHE27)on October 18,2019.     

Repairing whole facial nerve defects with xenogeneic acellular nerve grafts in rhesus monkeys

Acellular nerve allografts conducted via chemical extraction have achieved satisfactory results in bridging whole facial nerve defects clinically,both in terms of branching a single trunk and in connecting multiple branches of an extratemporal segment.However,in the clinical treatment of facial nerve defects,allogeneic donors are limited.In this experiment,we exposed the left trunk and multiple branches of the extratemporal segment in six rhesus monkeys and dissected a gap of 25 mm to construct a monkey model of a whole left nerve defect.Six monkeys were randomly assigned to an autograft group or a xenogeneic acellular nerve graft group.In the autograft group,the 25-mm whole facial nerve defect was immediately bridged using an autogenous ipsilateral great auricular nerve,and in the xenogeneic acellular nerve graft group,this was done using a xenogeneic acellular nerve graft with trunk-branches.Examinations of facial symmetry,nerve-muscle electrophysiology,retrograde transport of labeled neuronal tracers,and morphology of the regenerated nerve and target muscle at 8 months postoperatively showed that the faces of the monkey appeared to be symmetrical in the static state and slightly asymmetrical during facial movement,and that they could actively close their eyelids completely.The degree of recovery from facial paralysis reached House-Brackmann grade II in both groups.Compound muscle action potentials were recorded and orbicularis oris muscles responded to electro-stimuli on the surgical side in each monkey.Fluoro Gold-labeled neurons could be detected in the facial nuclei on the injured side.Immunohistochemical staining showed abundant neurofilament-200-positive axons and soluble protein-100-positive Schwann cells in the regenerated nerves.A large number of mid-graft myelinated axons were observed via methylene blue staining and a transmission electron microscope.Taken together,our data indicate that xenogeneic acellular nerve grafts from minipigs are safe and effective for repairing whole facial nerve defects in rhesus monkeys,with an effect similar to that of autologous nerve transplantation.Thus,a xenogeneic acellular nerve graft may be a suitable choice for bridging a whole facial nerve defect if no other method is available.The study was approved by the Laboratory Animal Management Committee and the Ethics Review Committee of the Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University,China(approval No.2018-D-1)on March 15,2018.     

Reinnervation by the contralateral facial nerve in patients with peripheral facial palsy

Introduction: Reinnervation activity is triggered after complete unilateral peripheral facial palsy (PFP). Methods: In 27 patients with PFP we recorded electromyographic activity with a concentric needle electrode inserted 1 cm lateral to the oral commissure of the affected side. We applied electrical stimuli to the unaffected (contralateral) facial nerve from the tragus to the mid‐lower lip and measured the response latency variability and segmental conduction velocity. Results: Responses to electrical stimulation of the unaffected facial nerve were found in all patients. Mean conduction velocity was 49.6 ± 6.2 m/s between tragus and oral commissure, and 6.0 ± 1.9 m/s between oral commissure and mid‐lower lip. Latency variability was 0.27 ms to facial nerve stimulation and 0.08 ms to oral commissure stimulation. Conclusion: Short distance sprouting of axons that innervate muscle fibers, which originate from the unaffected facial nerve, results in propagation of impulses to muscle fibers in the midline. Muscle Nerve 2011     

Insulin-like growth factor-I promotes nerve regeneration through a nerve graft in an experimental model of facial paralysis

Among the pathological sequelae of facial paralysis is a paralytic eye. Apart from the psychological and aesthetic deficits, facial paralysis if left untreated can lead to dryness, ulceration and eventual blindness. Although numerous restorative microsurgical approaches have been introduced to address the sequelae of this problem, complete restoration of function to denervated facial muscles remains elusive.Utilizing the rat model of facial paralysis the present research has as an objective to examine a dual treatment approach. Specifically, this study combined the current microsurgical treatment of the cross-facial nerve graft with local administration of insulin-like growth factor I (IGF-I).The efficacy of this combined approach (cross-facial nerve graft + IGF-I) was assessed in the following ways: (a) behavior measurement of the blink response and (b) histomorphometry light and electron microscopy of the entire nerve graft. These data will help provide insight into the restoration of facial muscle function after trauma and assist in the future development of more potent treatment strategies.7he local adnünistration of IGF-I (50 micro g/ml) to the cross-facial nerve graft was found to restore the blink response faster and to strengthen the degree of eye closure. Light microscopy examination revealed that IGF-I significantly enhanced axonal regeneration within a nerve graft (a 22% increase in the mean number of axons), and increased the mean nerve fiber diameter and myelin thickness. Electron microscopy assessment of the nerve grafts demonstrated that the IGF-I treated grafts possessed a greater density of microtubules, which were evenly distributed within the axoplasm.     

神经桥接与导管套接修复猫动眼神经形态学观察

目的探求导管修复颅内段动眼神经的可行性.方法 20只健康家猫随机分为2组.将右侧动眼神经于脑池段切断后,分组采用自体神经桥接和导管套接的方法修复.术后14周末光镜、电镜观察神经纤维的连续性、再生纤维数目和直径.结果神经修复14周后,神经桥接组67%、导管套接组75%的动物其动眼神经功能均有一定程度的恢复.形态学显示两组均取得较好的神经再生效果,两组间再生纤维直径差异无显著性(P>0.05),但导管套接组再生神经纤维数目较多,差异有显著性(P<0.05).结论导管套接法可作为颅内段动眼神经损伤后的一种修复方法,其疗效近似或稍优于神经桥接法.     

Mandibular nerve involvement in diabetic polyneuropathy and chronic inflammatory demyelinating polyneuropathy

Sensory complaints in the area of the mandible and mouth often escape notice or remain undiagnosed. Using electromyographic recording of the trigeminal reflexes and motor responses, we sought trigeminal dysfunction in 50 patients with peripheral neuropathy, and tried to gain pathophysiological information on the mechanisms provoking trigeminal damage. Trigeminal reflex recordings (early and late blink reflex after supraorbital stimulation, early and late masseter inhibitory reflex after mental stimulation, and jaw jerk) disclosed abnormalities caused by sensory trigeminal neuropathy in 8 out of 15 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 13 out of 23 patients with severe diabetic polyneuropathy, and in none of 12 patients with mild diabetic polyneuropathy. Six patients had abnormal motor responses in facial or masseter muscles. The response affected most frequently was the masseter early inhibitory reflex (also called first silent period, SP1) after mental nerve stimulation, its latency being strongly delayed. We found these long delays not only in patients with CIDP, but also in diabetic patients with severe polyneuropathy. We conclude that peripheral polyneuropathies often cause subclinical damage to the trigeminal nerve, especially to its mandibular branch. We believe that the nerve fibers running along the alveolar–mandibular pathway are more exposed to damage because of their cramped anatomical route in the mandibular canal and below the internal pterygoid muscle and fascia. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1673–1679, 1998     

Trigeminal nerve repetitive stimulation in myasthenia gravis

The aim of this study was to evaluate the utility of repetitive nerve stimulation (RNS) of the trigeminal nerve in assessing patients with myasthenia gravis (MG). In 26 normal controls and 21 patients with myasthenia gravis (MG), 2-Hz repetitive stimulation of the trigeminal nerve was performed using a monopolar needle for percutaneous nerve stimulation and recording over the surface of the masseter. In the MG patients, repetitive stimulation of the ulnar, spinal accessory, and facial nerves was also performed. The mean percent decrement in the compound muscle action potential (CMAP) amplitude among the different nerves at rest were: ulnar, 4.3%; spinal accessory, 10.1%; facial, 14%; and trigeminal, 17.3%. The facial nerve demonstrated abnormal decrement in 57% of all patients, compared with the spinal accessory (48%), trigeminal (43%), and ulnar (20%) nerves. All patients tolerated trigeminal RNS better than or as well as facial RNS. The study demonstrates that trigeminal RNS is a safe, reliable, efficient, and well-tolerated technique that provides another cranial nerve-muscle combination that can be used to supplement repetitive stimulation of other limb or cranial nerves in the evaluation of patients with bulbar or generalized MG.     

Management iatrogener N.-accessorius-Läsionen

Lesions of the spinal accessory nerve are usually iatrogenic, especially after lymph node extirpation on the neck. Between 1994 and 2003, 31 patients were operated on in the Neurosurgical Department of the University of Ulm for iatrogenic lesions of the XIth cranial nerve. Of 31 patients, 22 had undergone a previous lymph node extirpation, 2 had been injured during a selective peripheral denervation for spasmodic torticollis, and the other 7 patients by different causes. The neurosurgical intervention was performed 0-19 months after trauma (mean 7.2 months). All patients showed paresis/atrophy of the trapezius muscle, and the abduction of the shoulder was markedly reduced. Additional neck and/or shoulder pain was present in 29 of 31 cases. In seven cases, the nerve was compressed by scar tissue and subsequently treated by external neurolysis. Ten patients underwent an end-to-end anastomosis; autologous sural nerve grafting was necessary in 13 cases. After a mean follow-up of 12.6 months, 7of 31 patients completely recovered. Of 31 patients, 19 experienced partial relief of pain and weakness. Only five patients remained unchanged. The clinical findings after autologous nerve grafting, end-to-end reconstruction, or external neurolysis did not show any significant differences. Microsurgical reconstruction of iatrogenic injury of the spinal accessory nerve is very promising if the interval between trauma and surgical revision is less than 6 months. Up to 12 months, partial recovery can be achieved. Outcome after longer delay is unsatisfactory.     

面肌痉挛显微神经血管减压术中诱发肌电图监测的意义

目的探讨术中面肌异常诱发肌电图监测对显微神经血管减压术的指导意义。方法40例面肌痉挛患者在面肌异常诱发肌电图监测下行显微神经血管减压术。开颅前将刺激电极刺入患侧眼轮匝肌用以刺激面神经颧支，记录电极刺入患侧El轮匝肌用以记录诱发肌电图，分别在硬脑膜切开前、排放脑脊液、剥离压迫血管、垫入Teflon棉后、硬脑膜缝合完毕后行电刺激及记录诱发肌电图。结果39例于术前记录到潜伏期约10毫秒的异常诱发肌电图波形，手术后38例异常诱发反应消失。术后随访5年2个月至6年4个月，平均5年8个月，手术治愈率94．7％，好转率2．6％，复发率2．6％。结论术中面肌异常诱发肌电图监测可客观地指导和判断责任血管和减压效果，对提高手术治愈率具有较高的实用价值。     

Effects of delayed repair of peripheral nerve injury on the spatial distribution of motor endplates in target muscle

Motor endplates(MEPs) are important sites of information exchange between motor neurons and skeletal muscle, and are distributed in an organized pattern of lamellae in the muscle. Delayed repair of peripheral nerve injury typically results in unsatisfactory functional recovery because of MEP degeneration. In this study, the mouse tibial nerve was transected and repaired with a biodegradable chitin conduit, immediately following or 1 or 3 months after the injury. Fluorescent α-bungarotoxin was injected to label MEPs. Tissue optical clearing combined with light-sheet microscopy revealed that MEPs were distributed in an organized pattern of lamellae in skeletal muscle after delayed repair for 1 and 3 months. However, the total number of MEPs, the number of MEPs per lamellar cluster, and the maturation of single MEPs in gastrocnemius muscle gradually decreased with increasing denervation time. These findings suggest that delayed repair can restore the spatial distribution of MEPs, but it has an adverse effect on the homogeneity of MEPs in the lamellar clusters and the total number of MEPs in the target muscle. The study procedures were approved by the Animal Ethics Committee of the Peking University People's Hospital(approval No. 2019 PHC015) on April 8, 2019.     

Enlarged perivascular spaces and lacunar infarction★ Cerebral magnetic resonance evaluation

BACKGROUND： Previous studies have demonstrated that enlarged perivascular spaces （EPVS） are a result of microvascular disease. To date, there are few reports about the relationship between EPVS and lacunar infarction.
OBJECTIVE： To investigate whether EPVS is associated with lacunar infarction on the basis of cerebral magnetic resonance （MR） examination, clinical symptoms and signs, and past medical history of patients.
DESIGN, TIME AND SETTING： Case contrast analysis was performed at the Department of Neurology, Shanghai Ninth People＇s Hospital from January 2007 to January 2008.
PARTICIPANTS： Sixty-eight patients with lacunar infarction were admitted to the Department of Neurology of Shanghai Ninth People＇s Hospital, including 37 cases with first-ever infarction, and 31 with infarction recurrence. In addition, 53 healthy people were selected as controls.
METHODS： All participants underwent past medical history investigation, nervous system examination, and cranial MR. The subjects were assessed using the JMW rating scale to identify the EPVS grade.
MAIN OUTCOME MEASURES： EPVS scores of patients and controls; risk factors for cerebral vascular disease in patients with first-ever or recurrence of lacunar infarction.
RESULTS： The EPVS grade from lacunar infarction patients was significantly higher than of the control group （P 〈 0.05）. The EPVS grade in patients with recurring lacunar infarction was significantly higher than in patients with first-ever infarction （P 〈 0.05）. In addition, hypertension incidence in patients with recurring lacunar infarction was significantly higher than in patients with first-ever infarction （P 〈 0.05）.
CONCLUSION： Results indicate that EPVS is related to the incidence of lacunar infarction. Earlier screening of EPVS, and the evaluation of EPVS severity, is of great importance to control the risk factors for cerebral vascular disease and to prevent lacunar infarction.     

Axon reflexes or ephaptic responses simulating blink reflex R1 after XII-VII nerve anastomosis

It has been claimed that functional recovery of the blink reflex occurs after hypoglossal-facial nerve anastomosis. This has been explained through central nervous system plasticity and reorganization of neuronal connections. In 5 patients with reinnervated facial muscles after hypoglossal-facial nerve anastomosis, we observed “R1-like” responses that fulfilled criteria for facial nerve axon reflexes or ephapses. First, displacement of the stimulating electrode from the supraorbital to the zygomatic area shortened the latency of the evoked response. Second, these responses were stable (jitter mean consecutive difference < 25 μs) and they had complex potential shapes unmodified by high-frequency stimulation. Finally, collision techniques demonstrated antidromic conduction of impulses in the facial nerve from supraorbital to zygomatic points. Therefore, these “R1-like” responses are not the early component of a functionally recovered blink reflex but motor axon reflexes or ephaptic responses similar to the short latency responses observed following facial nerve regeneration or from sutured nerves in human forearms. © 1996 John Wiley & Sons, Inc.     

Phrenic nerve transfer to the musculocutaneous nerve for the repair of brachial plexus injury: electrophysiological characteristics

Phrenic nerve transfer is a major dynamic treatment used to repair brachial plexus root avulsion. We analyzed 72 relevant articles on phrenic nerve transfer to repair injured brachial plexus that were indexed by Science Citation Index. The keywords searched were brachial plexus injury, phrenic nerve, repair, surgery, protection, nerve transfer, and nerve graft. In addition, we performed neurophysiological analysis of the preoperative condition and prognosis of 10 patients undergoing ipsilateral phrenic nerve transfer to the musculocutaneous nerve in our hospital from 2008 to 201 3 and observed the electromyograms of the biceps brachii and motor conduction function of the musculocutaneous nerve. Clinically, approximately 28% of patients had brachial plexus injury combined with phrenic nerve injury, and injured phrenic nerve cannot be used as a nerve graft. After phrenic nerve transfer to the musculocutaneous nerve, the regenerated potentials first appeared at 3 months. Recovery of motor unit action potential occurred 6 months later and became more apparent at 12 months. The percent of patients recovering ‘excellent' and ‘good' muscle strength in the biceps brachii was 80% after 18 months. At 12 months after surgery, motor nerve conduction potential appeared in the musculocutaneous nerve in seven cases. These data suggest that preoperative evaluation of phrenic nerve function may help identify the most appropriate nerve graft in patients with an injured brachial plexus. The functional recovery of a transplanted nerve can be dynamically observed after the surgery.     

面神经远端血管压迫对面肌痉挛手术疗效的影响

目的 探讨面神经远端血管压迫对面肌痉挛显微血管减压术疗效的影响.方法 采用监测面神经侧方扩散反应(LSR)的方法,对120例面肌痉挛患者进行术中监测,通过对39例单纯面神经根出脑干区减压后LSR未消失的病例探查而神经蛛网膜下腔段全长(面神经远端),发现19例面神经远端存在血管压迫,进行充分减压,记录监测结果并观察手术疗效.结果 手术结束时15例LSR消失,4例LSR未消失.术后面肌痉挛症状完全消失13例,减轻但未完全消失6例.随访8-14个月,平均12.7个月,所有患者面肌痉挛症状均完全消失,无复发病例.术后并发症包括:中度面瘫2例,均于随访期间恢复正常;听力丧失1例,未恢复;听力下降3例,随访期间1例恢复正常,2例较前好转;颅内感染1例,住院期间完全控制.结论 面神经远端血管压迫对面肌痉挛手术的疗效有明确影响,根据监测结果对其进行减压能够降低术后延迟治愈的发生率并减少盲目处理面听神经相关血管导致并发症的发生.

Abstract：

Objectiye To study the influence of distal portion compression of the facial nerve in hemifacial spasm surgery.Method 120 hemifacial spasm patients were undergone lateral spread response monitoring during microvascular decompression surgery.39 patients' LSR remained after decompression of the root exit zone of the facial nerve.After exploring the full length of distal portion of the facial nerve in the subarachnoid space, 19 patients were found distal portion vascular compression and were fully decompressed.The monitoring records as long as the surgical results were analyzed post - operatively.Results At the end of operations, 15 patients' LSR disappeared and 4 remained.The HFS disappeared immediately in 13patients.The post - operative spasm was weaker in 6 patients.After follow - up period of 8 - 14 months ( mean duration 12.7 months), all patients were spasm free and no reoccurrence case.Post - operative complications included:2 cases of transient moderate facial paralysis, 1 case of hearing loss, 3 cases of transient hearing impairment and 1 case of intracranial infection.Conclusions Distal portion compression of the facial nerve has influence on the result of microvascular decompression surgery.Distal decompression which identified by intraoperative monitoring can decrease the occurrence of delayed resolution and minimize the complications related with decompression of the vascular attached to the Ⅶ and Ⅷ nerve.     

微血管减压术对桥小脑角区颅神经疾病合并高血压患者术后血压的影响

目的 探讨微血管减压术（MVD）对桥小脑角区颅神经疾病合并高血压患者术后血压的影响。方法 2010年11月至2013年12月收治桥小脑角区颅神经疾病患者合并高血压患者92例（颅神经疾病位于左侧59例、右侧33例;三叉神经痛14例、面肌痉挛28例、舌咽神经痛50例）,应用乙状窦后入路微血管减压术治疗。结果 92例患者中,术后高血压缓解59例（左侧减压手术53例,右侧减压手术6例）,其中脱离高血压用药34例,均为左侧减压手术患者;术后高血压无明显变化33例。总有效率为64.13%（59/92）,其中左侧减压手术有效率为89.83%（53/59）,右侧减压手术有效率为18.18%（6/33）;左侧减压手术治愈率为57.63%（34/59）。左侧颅神经疾病患者术后血压较术前明显降低（P<0.05）,而右侧颅神经疾病患者术后血压无明显变化（>P>0.05）。结论 对左侧桥小脑角区颅神经疾病患者合并高血压患者,微血管减压术具有一定的降血压效果。     

Agmatine treatment and vein graft reconstruction enhance recovery after experimental facial nerve injury

The rate of nerve regeneration is a critical determinant of the degree of functional recovery after injury. Here, we sought to determine whether treatment with the neuroprotective compound, agmatine, with or without nerve reconstruction utilizing a regional autogenous vein graft would accelerate the rate of facial nerve regeneration. Experiments compared the following seven groups of adult male rats: (A) Intact untreated controls. (B) Sham operation with interruption of the nerve blood supply (controls). (C) Transection of the mandibular branch of the facial nerve (generating a gap of 3 mm) followed by saline treatment. (D) Nerve transection with unsutured autogenous vein (external jugular) graft reconstruction plus saline treatment. (E) Nerve transection with sutured vein graft approximation (coaptation of the proximal and distal nerve stumps) plus saline. (F) Nerve transection with sutured vein graft followed by agmatine treatment (four daily intraperitoneal injections of 100 mg/kg agmatine sulfate). (G) Nerve transection with unsutured vein graft followed by agmatine treatment. Functional recovery, as assessed by grading vibrissae movements and by recording nerve conduction velocity and numbers of regenerated axons, indicated that either vein reconstruction or agmatine treatment resulted in accelerated and more complete recovery as compared with controls. But best results were observed in animals that underwent combined treatment, i.e., vein reconstruction plus agmatine injection. We conclude that agmatine treatment can accelerate facial nerve regeneration and that agmatine treatment together with autogenous vein graft offers an advantageous alternative to other facial nerve reconstruction procedures.     

Hemihypoglossal-facial nerve anastomosis for facial nerve palsy

BACKGROUND AND PURPOSE : Commonly used classic hypoglossal (CN XII) to facial nerve (CN VII) anastomosis has the disadvantage of tongue hemiatrophy. Thus, various attempts have been made to modify this method to reduce the tongue damage. The aim of this report was to present the results of hemihypoglossal-facial nerve anastomosis (HHFA) technique in relation to facial muscles reanimation and hemitongue atrophy. MATERIAL AND METHODS : The first 7 consecutive patients who underwent CN VII anastomosis with half of the CNXII, for which the follow-up period exceeded 12 months, were analysed. During the procedure, CN VII was transected as proximally as possible after drilling the mastoid process. CN XII was separated longitudinally into two parts at a short distance to allow suture of the stumps without any tension. One half of CN XII was transected and sutured to the distal stump of CN VII. Recovery from facial palsy was quantified with the House-Brackmann grading system (HB). Tongue function was assessed according to the scale proposed by Martins. RESULTS : Features of initial reinnervation of facial muscles were visible after 6 months in all 7 patients. All patients achieved satisfactory outcome of CN VII regeneration (HB grade III) until the last control examination (12-27 months after surgery, mean 16). No or minimal tongue atrophy without deviation (grades I-II according to the Martins scale) was found in 4 patients. Mild hemiatrophy with tongue deviation < 30 degrees (grade III) was visible in 3 patients. CONCLUSIONS : In our experience, HHFA is effective treatment of facial palsy and gives a chance to reduce damage of the tongue.     

Related timing for peripheral and central plasticity in hypoglossal-facial nerve anastomosis

The aim of this work was to determine the role of peripheral facial muscle reinnervation in the central reorganization of the blink reflex (BR) after hypoglossal-facial anastomosis (HFA). An electrophysiological study was performed on seven patients who underwent HFA after facial nerve transection during surgery for acoustic neuroma. HFA was performed within 15 days after surgery in five patients (group 1) and later for the two others (group 2). We studied the motor responses (MR) and the BR evoked on the affected side, before and over 3 years after the HFA. The MR appeared by the third month for the first group, and by the sixth and twelfth for the second group. After 36 months, the amplitude of MR was significantly higher than its control value, showing hyperinnervation of the facial muscles. Study of the BR evoked only an R1-type blink response that was observed 4 and 6 months after the MR for groups 1 and 2, respectively. This central reorganization appeared closely correlated with muscle reinnervation and its related timing. The occurrence of peripheral nerve-muscle contacts seems to be a necessary condition for reorganization of the trigemino-hypoglossal-facial reflex.