Hemifacial spasm due to vascular compression of the distal portion of root exit zone of the facial nerve: report of two cases

It has been generally assumed that only vascular contact at the root exit zone (REZ) of the facial nerve can cause hemifacial spasm. We treated two cases of hemifacial spasm in which compression of the distal site of the REZ of the facial nerve produced symptoms. The microvascular decompression for the patients showed excellent results. Extreme care must be taken not to stretch the internal auditory artery during surgical manipulation. The ABR monitoring is useful to prevent the postoperative hearing loss. It must be kept in mind that the compression of distal portions of the facial nerve may be responsible for hemifacial spasm in cases in which neurovascular compression at the REZ is not confirmed intraoperatively.     

Anatomical study of the central myelin portion and transitional zone of the vestibulocochlear nerve

Background

The aim of this study was to evaluate gross and microscopic anatomical features of the vestibulocochlear nerve or eighth cranial nerve (CNVIII) from fresh cadavers, especially the nerve’s central myelin portion (CMP) and transitional zone (TZ), and to consider any pathological implications.

Methods

Six fresh cadavers were used to examine the CNVIII. Its cisternal length from brainstem to internal auditory meatus was measured. Longitudinal sections were stained to make following measurements: the diameter where the nerve enters the brainstem, the diameter where the TZ begins, the distance to the most distal part of TZ from the brainstem, and the depth of the TZ. The volume of the CMP was calculated as well.

Results

The cisternal length of ten CNVIIIs measured between 14.2 and 19.2 mm (16.48 ±1.78 mm). The thickness where the CNVIII enters the brainstem was between 1.21 and 3.16 mm (2.31?±?0.68 mm); the thickness where the TZ begins was between 1.07 and 2.21 mm (1.44?±?0.38 mm); the distance of the most distal part of the TZ from the brainstem was between 9.28 and 13.84 mm (11.50?±?1.56 mm); the depth of the TZ was between 0.56 and 1.28 mm (0.81?±?0.27 mm). The volume of the CMP was between 17.34 and 53.87 mm³ (33.98?±?13.74 mm³). The measurements were compared to trigeminal, facial, glossopharyngeal and vagus nerves. CNVIII was the nerve with the longest CMP.

Conclusions

The measurements showed that the CMP of CNVIII was very long. The implication of this length in the dysfunctional syndromes of this nerve, its propensity to harbor schwannomas, which most frequently arise at the porus of the auditory meatus, and the vulnerability to damages are discussed.     

Preservation of peripheral nerve grafts with Schwann cell culture medium

Preservation of peripheral nerves may, in the near future, play an important role in reconstructive surgery, especially if recent advances in immunosuppressive therapy are taken into account. Therefore, it has to be investigated whether peripheral nerves can be stored for some time after harvesting without diminishing their regenerative potential. Previous experiments of our group could demonstrate only little benefit of organ storage solution (HTK) or normal saline (NaCI 0.9%) to peripheral nerves when kept at cold ischaemia of 4°C for 32 and 72 hours. In this presentation, we are reporting the results of peripheral nerve storage in Dulbecco's Modified Eagle Medium which has been used for Schwann cell culture. In 30 adult Sprague-Dawley rats, a 2.5 cm segment of the right sciatic nerve was harvested and kept at 4°C for 14, 32, 72, and 120 hours. It was then reimplanted into the donor animal; regeneration quality was assessed clinically, histologically and morphometrically after 6 weeks. Best regeneration results were obtained in the 32 and 72 hour groups; regeneration here was comparable to the normal controls. These results are explained with the positive effect of nerve predegeneration. © 1993 Wiley-Liss Inc.     

雪旺细胞构建人工神经在大鼠长段神经缺损中的修复作用研究

[目的]研究雪旺细胞与PLGA构成的组织工程化人工神经修复大鼠周围神经缺损的效果。[方法]将雪旺细胞接种在内置polyglactin910纤维的PLGA中空管，构建成组织工程人工神经。将60只SD大鼠随机分3组，每组20只，建立大鼠坐骨神经缺损20mm的动物模型。A组用切下的自体神经段原位缝合，B组使用雪旺细胞组织工程人工神经进行修复，C组用未接种雪旺细胞的PLGA中空管进行修复。术后8、12周使用神经电生理和组织学观察分别进行效果评价。[结果]在大体观察、组织学观察中，B组的恢复表现与A组相近。在神经电生理检测、小腿三头肌肌肉重量测定、桥接物横切面神经纤维数量测定的结果分析中B组略低于A组但明显高于C组。B组大鼠桥接段远端辣根过氧化酶示踪后在脊髓前角可以看到被标记的神经元。透射电镜可见B组桥接物中段大量的再生神经纤维。[结论]用雪旺细胞和PLGA构建组织工程人工神经修复大鼠外周神经缺损，可以修复20mm的长段周围神经缺损，并可获得接近于大鼠自体神经修复的效果。     

许旺细胞源神经营养因子受体在外周神经组织中的分布研究

目的探讨许旺细胞源神经营养因子(SDNF)受体在外周神经的分布状况.方法应用放射性受体结合法检测外周神经组织中125I-SDNF的特异性结合.结果外周神经组织中存在许旺细胞源神经营养因子的特异性结合位点,且该特异性结合位点具有如下特点(1)高亲和力,Kd为(93.11±0.52)pmol/L;(2)低结合容量,Bmax为(8.91±0.26)fmol/mg;(3)可饱和性,饱和曲线呈双曲线型,Scatchard分析的回归线呈直线;(4)可逆性,结合常数K1为(3.91±0.63)×107M-1×min,解离常数K-1为(3.38±0.54)×10-3min-1;(5)特异性.结论外周神经组织中存在许旺细胞源神经营养因子的高亲和力受体,故为许旺细胞源神经营养因子发挥神经营养作用的靶组织.     

Histologic analysis of Schwann cell migration and peripheral nerve regeneration in the autogenous venous nerve conduit (AVNC)

Over the last two decades, the autogenous venous nerve conduit (AVNC) has been established as an effective treatment modality for the repair of nerve gaps less than 3 cm. In this study, the spatial-temporal progression of Schwann-cell migration and peripheral-nerve regeneration across a 10-mm gap bridged by a venous conduit was examined, using immunoctyochemical techniques. Histologic analysis revealed that the process of nerve regeneration through an AVNC occurs in four phases: the hematoma phase, cellular migration phase, axonal advancement phase, and myelination and maturation phase. The authors found that: 1) the lumen of the vein conduit remains patent throughout the process of nerve regeneration; 2) Schwann cells migrate into the vital space of the vessel lumen from the proximal and distal nerve stumps; 3) axonal growth into the conduit lags behind Schwann-cell migration; 4) Schwann cells migrate to the regenerating axons to form mature nodes of Ranvier when the distal stump is present; and 5) mechanical injury alone is sufficient to induce axonal outgrowth from the proximal nerve stump.     

胶质细胞源性神经营养因子基因修饰的雪旺细胞对大鼠坐骨神经缺损的修复作用

目的　研究胶质细胞源性神经营养因子 (glialcellline derivesneurotrophicfactor ,GDNF)基因对周围神经断伤后促进轴突再生及神经元的保护作用。方法　应用体外获取的GDNF修饰的雪旺细胞结合细胞外基质凝胶及生物可降解聚乳酸 聚羟基乙酸共聚物管 (polyCDL lactide co glycolide ,PLGA)构建的神经移植复合体 ,修复大鼠坐骨神经的缺损。 2 0只成年Wistar大鼠按桥接物的不同随机分为 4组 ,每组 5只。A组 :细胞外基质凝胶 PLGA管桥接组 ;B组 :雪旺细胞 细胞外基质凝胶 PLGA管桥接组 ;C组 :GDNF基因修饰的雪旺细胞 细胞外基质凝胶 PLGA管桥接组 ;D组 :自体神经桥接组。术后 12周检测运动神经传导速度 ,并进行再生神经的组织形态学观察以及计量学分析。结果　术后 12周 ,坐骨神经的运动神经传导速度 ,轴突数、髓鞘的厚度、神经纤维的直径、神经组织面积的百分比和脊髓前角运动神经元存活率等 ,C组均优于A、B组 (P <0 .0 1) ,而与D组相比无明显差异 (P >0 .0 5 )。结论　雪旺细胞的转基因处理可能弥补单纯细胞移植神经营养因子含量的不足 ,而达到与自体神经移植相似的效果。     

周围神经创伤中S-100蛋白与雪旺细胞活化关系

目的探讨周围神经创伤变性中雪旺细胞S-100蛋白的生理作用.方法将74只SD大鼠随机分为12组.1个正常空白组(8只),11个实验组(66只).每只实验组大鼠双后肢再随机分为试验肢(构成试验组)和对照肢(构成对照组).分别于术后1小时、6小时、12小时、24小时、2天、3天、4天、8天、14天、21天、30天共11个时相点,切取坐骨神经中下段标本.检测各组神经纤维形态学改变,雪旺细胞S-100表达水平变化.结果试验组显示华勒氏变性,雪旺细胞数在24小时后下降,3～4天后罕见,8天开始增加,14天形成Bungner带.各组S-100普遍低水平表达.与正常空白组相比,对照组变化无统计学显著性意义(P＞0.05),试验组术后1小时、21天变化有统计学显著性意义(P＜0.05).结论在周围神经创伤变性中,S-100与雪旺细胞的应急反应、增殖重建有关,反映雪旺细胞的功能活化状态.     

自体雪旺细胞促周围神经端侧吻合轴突侧支发芽的实验研究

目的：研究周围神经损伤行端侧吻合口自体雪旺细胞（Sc)移植对端侧吻合的作用，探讨改善端铁合质量的方法。方法：72只Wistar大鼠随机平均分为3组：A组，左腓神经端端吻合组；B组，左胫腓神经端侧吻合组；C组，左胫腓神经端侧吻合后再生小室内注自体雪旺细胞悬液组。于术后2、4、6个月每组分别取8只大鼠取材、检测，依次行大体观察、神经电生理检测、肌湿重、组织学及电镜观察等。结果：C组与B组各项指标比较：肌力、肌纤维截面积、有髓纤维截面积差异有显著性（P＜0．05）。神经电生理、肌湿重、有髓纤维数目差异有非常显著性（P＜0．01），显示恢复较好，某些指标（神经电生理、肌湿重、肌纤维截面积）在6个月时接近A组（P＞0．05）。结论：自体雪旺细胞移植可以促进周围神经端侧吻合轴突侧支发芽，改善端侧吻合口质量。     

几丁糖胶原复合膜及激活态雪旺细胞修复周围神经缺损的实验研究

目的研究几丁糖胶原复合膜、激活态雪旺细胞(activatedSchwanncell,ASC)促进周围神经再生的作用。方法将激活态雪旺细胞培养于几丁糖胶原复合膜后,将膜缝制成导管修复大鼠坐骨神经10mm的缺损(D组);并以自体神经移植(A组)、几丁糖胶原复合膜管(B组)及几丁糖胶原复合膜加脑源性神经营养因子[(brainderivedneurotrophicfactor,BDNF)C组]为对照。术后4、8、12周观察肢体运动,复合肌肉动作电位(CMAP)的波幅、潜伏期和运动神经传导速度(MNCV)。术后12周取材,样本染色观察神经轴突再生情况。结果几丁糖胶原复合膜加激活态雪旺细胞修复10mm神经缺损的效果优于几丁糖胶原复合膜加BDNF,与自体神经相似。结论几丁糖胶原复合膜加激活态雪旺细胞能有效地促进周围神经再生。     

Schwann cell apoptosis in Wallerian-degenerated sciatic nerve of the rat

Objective: To investigate systematically Schwann cell apoptosis in Wallerian-degenerated sciatic nerve of the rat, and evaluate its time-related feature. Methods: Ninety-five SD rats were divided randomly into one normal group (8 rats) and 11 experimental groups (66 rats, 6 in each). Both hind legs of each rat in experimental groups were randomly divided into test leg (sciatic nerve transected ) and control one (nerve uninjured). All test legs constituted a test group and all control legs constituted a control one. After operation, all rats were respectivdy sacrificed at 1 h, 6 h, 12 h, 24 h, 2 d, 3 d, 4 d, 8 d, 14 d, 21 d, and 30 d. We analyzed the specimens of mid-distal sciatic nerve, especially the morphological changes of the nerve, the different expression levels of S-100 protein and apoptosis-related proteins such as Bel-2, Bax, and Fas in Schwann cells. The TUNEL method was used to detect the apoptotic rate of Schwann cells. Results： (1) The test group showed Wallerian degeneration. The number of Schwann cells began to decrease at 24 h, obviously decreased on day 3 and 4, then began to increase from day 8 and formed Bungner belt after 14 days. (2) Schwann cells generally expressed S-100 at a low level in all groups. The control group was not significantly different from the normal group. The test group had statistical significance at 1 h and day 21. (3) As an inhibitory gene protein of Schwann cell apoptosis, Bcl-2 positive rates in the control and test groups apparently elevated and were statistically different from the normal group. (4) As a promotive gene protein of Schwann cell apoptosis, the control and test groups expressed Bax at a high level and were statistically different from the normal group. (5) As a promotive gene protein of Schwann cell apoptosis, Fas positive rate in control group was slightly elevated, but had no statistical significance compared with the normal group. Fas positive rate in test group continuously elevated in a fluctuant way, with highly statistical significance compared with the normal group. (6) TUNEL detection further proved that Schwann cell apoptosis rarely existed in the normal group, and the left sciatic nerve had no statistical significance compared with the right sciatic nerve. While the test group showed lots of apoptotic nuclei at 6 h, 2 d, 4 d, and 21 d. It had highly statistical significance compared with the normal group. Conclusions: Schwann cell apoptosis does exist in Wallerian-degenerated sciatic nerve of the rat after transection. Schwann cell apoptosis and its apoptotic genes expression have a time-related feature.     

微囊化雪旺细胞/神经组织移植促进周围神经再生的实验研究

目的:探讨免疫隔离技术应用在神经细胞/组织移植促进周围神经再生的可行性.方法:采用静电液滴法制备海藻酸钠/聚赖氨酸/海藻酸钠(alginate-polysien-alginate,APA)微胶囊,包埋分离自SD大鼠周围神经的雪旺细胞(SChwann cells,SCs)/神经组织;采用台盼蓝拒染法和ELISA法检测其培养后活性和分泌神经生长因子情况.制备坐骨神经横断损伤的SD大鼠模型,将微囊化SCs/神经组织移植到实验组坐骨神经吻合口处.结果:微囊化SCs/神经组织培养一定时间后,仍保持活力和分泌神经生长因子的功能;4周后实验组吻合口远端可见到再生的阳性纤维,明显大于对照组,瘢痕明显少于对照组;实验组再生的神经纤维和新生的微小血管远较对照组密集.结论:微囊化SCs/神经组织移植后在局部持续分泌神经生长因子,有促进周围神经修复的作用.     

Hemifacial spasm following a blow to the mandible causing blunt injury to the peripheral facial nerve

A 40-year-old male presented with hemifacial spasm manifesting as paroxysmal spontaneous twitches in the left peribuccal region persisting for 3 months. The symptoms began 7 days after an accident, when a signboard hit his left mandibular angle. Physical examination showed no trauma-related change in his face, and no neurological abnormality except for the twitches. Magnetic resonance imaging also showed no abnormalities of the facial nerve and adjacent regions. Electrophysiological studies showed synkinesis, so hemifacial spasm caused by peripheral facial nerve injury was suspect- ed. The symptoms subsided 4 months after the injury. Blunt injury to the facial nerve branches might cause hemifacial spasm.     

Cranial nerve vascular compression syndromes of the trigeminal,facial and vago-glossopharyngeal nerves: comparative anatomical study of the central myelin portion and transitional zone; correlations with incidences of corresponding hyperactive dysfunctional syndromes

Objective  

The aim of this study was to evaluate the anatomy of the central myelin portion and the central myelin-peripheral myelin transitional zone of the trigeminal, facial, glossopharyngeal and vagus nerves from fresh cadavers. The aim was also to investigate the relationship between the length and volume of the central myelin portion of these nerves with the incidences of the corresponding cranial dysfunctional syndromes caused by their compression to provide some more insights for a better understanding of mechanisms.