神经导航引导经皮穿刺三叉神经半月节射频热凝治疗三叉神经痛的研究

目的 探讨神经导航引导下经皮穿刺三叉神经半月节射频热凝术在治疗三叉神经痛中的应用.方法 选取我科神经导航引导下经皮穿刺三叉神经半月节射频热凝治疗的156例患者资料.所有患者术前均经头部3D-CT薄层连续平扫,并将影像资料导入SteahhStation Tria Plus手术导航系统,图像经三维重建后,确认患侧卵圆孔作为靶点,在导航实时引导下进行卵圆孔穿刺,并行电生理测试,再次确认靶点的位置无误后,进行射频热凝治疗.结果 所有患者顺利穿刺成功,射频热凝术后,患者原有的面部疼痛均明显缓解或消失,术前患者VAS评分为9.67±0.47,术后VAS评分为0.22±0.57,差异有明显的统计学意义,且所有患者术后均无严重并发症.结论 神经导航引导下经皮穿刺三叉神经半月节射频热凝术是一种微创,安全和疗效显著的三叉神经痛外科治疗手段.     

Analysis of Occlusal Stresses Transmitted to the Inferior Alveolar Nerve by Multiple Threaded Implants

Background : Potential nerve injury or loss of sensation can occur after mandibular implant placement or loading. To avoid this type of damage, it is critical to determine the proper distance from implants to the mandibular nerve. Hence, the purpose of this study is to use biomechanical analyses to determine the safe distance from multiple implants to the inferior alveolar nerve. Methods: Using the boundary element method, a numerical mandibular model was designed to simulate a mandibular segment containing multiple threaded fixtures. This model allows assessment of the pressure, as induced by occlusal loads, on the trigeminal nerve. Such pressure distribution was evaluated against different distances from the fixtures to the mandibular canal, against the possible lack of the central fixture in a three‐abutment configuration, and against different levels of implant osseointegration. All the simulations considered a canal that is orthogonal to the implant axis. Results: Nerve pressure increased quickly when the implant–canal distance decreased in the range studied. Lack of the central implant to support the central abutment caused major increases in nerve pressure. Conclusions: This study suggests a minimal implant–canal distance of 1 mm to prevent inferior alveolar nerve damage caused by three connected implants. For clinical safety, an additional 0.5 mm is recommended as a cushion, so a 1.5‐mm minimal distance should be planned to avoid potential nerve injury.     

重度磨耗对大鼠三叉神经节中CGRP表达的影响

目的：探讨重度磨耗对大鼠三又神经节中降钙素基因相关肽（calcitonin gene—related petide,CGRP）表达的影响。方法：8周龄雄性SD大鼠75只,随机平均分为操作对照组、空白对照组和实验组,每组各25只,实验组用人工逐次磨低大鼠牙冠高度的方法建立重度磨耗动物模型。各组分别于干预后3、7、14、21、28天处死5只动物,取出双侧三叉神经节,通过免疫荧光染色的方法观察三叉神经节中CGRP的表达变化。结果：与空白对照组和操作对照组相比,实验组3天组和7天组的CGRP阳性神经元数量明显增加（P〈0．05）,14天组和21天组CGRP阳性神经元数量有所减少,但仍明显多于对照组（P〈0．05）,28天组基本恢复正常（P〉0．05）。结论：重度磨耗可导致大鼠三叉神经节内CGRP表达的可逆性变化。     

Neuroanatomy and neurochemistry of rat cornea: Changes with age

PurposeTo characterize the entire rat corneal nerve architecture, the changes that occur with aging, and its sensory, sympathetic, and parasympathetic fiber distribution.MethodsSprague-Dawley rats (aged 1 day to 2 years old) of both sexes were euthanized, and the whole corneas were immunostained with protein gene product 9.5 (PGP9.5). The specimens were double-labeled with antibodies against calcitonin gene-related peptide (CGRP) and substance P (SP) as sensory nerve markers, vasoactive intestinal peptide (VIP) as a parasympathetic nerve marker, and neuropeptide Y (NPY) and tyrosine hydroxylase (TH) as markers of sympathetic fibers. Relative nerve density positive for each antibody was assessed by computer-assisted image analysis.ResultsThick nerve trunks enter the cornea in the middle of the stroma and run towards the anterior stroma, subsequently dividing into smaller branches that penetrate upwards into the epithelium to form the subbasal nerve bundles. There was no significant difference in corneal innervation between sexes. CGRP and SP were the major sensory neuropeptides with 47.6% ± 3.5% and 34.9% ± 5.1%, respectively, of the total nerves. VIP was 18.4% ± 5.7%, and NPY and TH positive fibers took up 6.92% ± 2.66% and 2.92% ± 1.52%, respectively. Epithelial nerve density increased with age, reached full development at 5 weeks, and decreased at 120 weeks.ConclusionThis study provides a complete nerve architecture and content of components of sensory, parasympathetic, and sympathetic nerves in the rat cornea. The normal innervation pattern described here will provide an essential baseline for investigators who use the rat model for assessing corneal pathologies that involve nerve alterations.     

What is the best treatment of drug-resistant trigeminal neuralgia in patients affected by multiple sclerosis? A literature analysis of surgical procedures

Objective

Drug-resistant trigeminal neuralgia (TN) can complicate the clinical course of patients affected by multiple sclerosis (MS). Various surgical procedures have been reported for the treatment of this condition, but there is no agreement on the best management of these patients. To our knowledge, there is no critical literature analysis focusing on this particular topic. The aim of this study was to evaluate the clinical outcome of different surgical procedures utilized for drug-resistant TN in MS patients.

Methods

We reviewed the literature about the studies reporting on surgical treatment of drug-resistant TN in MS patients. Case reports and case series less than 4 patients were excluded from the analysis. Nineteen studies were selected for the statistical analysis. To reduce the variability of the data, the selected studies were evaluated for the following outcome parameters: acute pain relief rate (APR), rate of recurrence (RR), pain free at follow-up rate (PF at FU) and complication rate (CR). For the statistical analysis, chi-square statistic, using the Fisher's exact test was utilized.

Results

There was no procedure statistically superior in terms of APR rate in MS patients following the surgical treatment of TN. The highest RR was observed for percutaneous balloon compression (PBC) (60.2 ± 14.4%). This result was statistically significant when compared to gamma knife surgery (GKS) (p = 0.0129) and microvascular decompression (MVD) (p = 0.0281). MVD together with percutaneous radiofrequency rhizothomy (PRR) was associated with a statistically better PF at FU rate (56.5 ± 16.8% and 73.5 ± 14.2%, respectively). However PBC and MVD showed statistical significant minor CR compared to other techniques (no complications and 18.7 ± 17.4%, respectively).

Conclusion

Our study shows no differences in the short term results among different procedures for TN in MS patients. Each technique demonstrate advantages and limits in terms of long term pain, recurrence rate and complication rate. Each patient should be accurately informed on pros and cons of each procedure in order to be involved in the most appropriate choice.     

3D-FIESTA-C与3D-TOF-MRA 序列在血管压迫三叉神经痛中责任血管显示的比较研究

目的：比较三维双激发平衡式稳态自由进动序列（3D‐FIESTA‐C）与三维时间飞跃法磁共振血管成像（3D‐TOF‐MRA）在血管压迫三叉神经痛中责任血管显示的应用价值。方法回顾性分析行微血管减压术（M VD ）的60例三叉神经痛患者的磁共振资料,所有患者均采用3D‐T O F‐M RA和3D‐FIES T A‐C序列扫描,从原始及重建图像综合评判患侧三叉神经脑池段与周围血管的空间关系,以术中镜下所见为金标准,对比分析3D‐TOF‐MRA和3D‐FIESTA‐C序列预判接触血管的效能。结果判定是否存在责任血管,3D‐TOF‐MRA和3D‐FIESTA‐C序列灵敏度分别为85．7％、89．3％,特异度为75．0％、100％,准确率为85．0％、90．0％（P＝1．000）。在责任血管中,3D‐TOF‐MRA和3D‐FIESTA‐C序列判定责任动脉灵敏度分别为94．1％、88．2％（P＝0．244）,而责任静脉灵敏度为0．00％、88．2％（P＝0．009）。结论3D‐FIESTA‐C与3D‐TOF‐MRA序列均能有效显示责任血管,3D‐FIESTA‐C对责任静脉的显示优于3D‐TOF‐MRA ,可作为术前病因诊断的有力补充。     

Localization of P2X2 and P2X3 receptors in rat trigeminal ganglion neurons

Purine receptors have been implicated in central neurotransmission from nociceptive primary afferent neurons, and ATP-mediated currents in sensory neurons have been shown to be mediated by both P2X3 and P2X2/3 receptors. The aim of the present study was to quantitatively examine the distribution of P2X2 and P2X3 receptors in primary afferent cell bodies in the rat trigeminal ganglion, including those innervating the dura. In order to determine the classes of neurons that express these receptor subtypes, purine receptor immunoreactivity was examined for colocalization with markers of myelinated (neurofilament 200; NF200) or mostly unmyelinated, non-peptidergic fibers (Bandeiraea simplicifolia isolectin B4; IB4). Forty percent of P2X2 and 64% of P2X3 receptor-expressing cells were IB4 positive, and 33% of P2X2 and 31% of P2X3 receptor-expressing cells were NF200 positive. Approximately 40% of cells expressing P2X2 receptors also expressed P2X3 receptors and vice versa. Trigeminal ganglion neurons innervating the dura mater were retrogradely labeled and 52% of these neurons expressed either P2X2 or P2X3 or both receptors. These results are consistent with electrophysiological findings that P2X receptors exist on the central terminals of trigeminal afferent neurons, and provide evidence that afferents supplying the dura express both receptors. In addition, the data suggest specific differences exist in P2X receptor expression between the spinal and trigeminal nociceptive systems.     

Ongoing activity in trigeminal wide-dynamic range neurons is driven from the periphery

Ongoing activity of spinal trigeminal neurons is observed under various conditions and suggested to be responsible for ongoing headache. It can be spontaneous, i.e. arising intrinsically from the neuron, or the product of descending influences from other central neurons, or maintained by ongoing afferent input. The aim of the present study was to examine if ongoing activity of neurons in different subnuclei of the spinal trigeminal nucleus is driven from peripheral afferent input. Experiments were performed in Wistar rats anesthetized with isoflurane or Nembutal/urethane. Ongoing activity of single wide-dynamic range (WDR) neurons was recorded with carbon fiber glass microelectrodes in two subnuclei of the spinal trigeminal nucleus: oral (Sp5O) and caudal (Sp5C). Peripheral receptive fields were evaluated using von Frey filaments. Sp5O neurons received peripheral input from facial areas innervated by the mandibular branch of the trigeminal nerve. Units in Sp5C had receptive fields in the surgically exposed dura mater and in facial areas innervated by the ophthalmic and maxillary branch of the trigeminal nerve. Saline or the local anesthetic lidocaine was locally applied onto the exposed dura mater or microinjected into V3 (for Sp5O units) or V1/V2 (for Sp5C units) divisions of the trigeminal ganglion via the infraorbital channel. Local application of lidocaine onto the exposed dura caused mechanical insensitivity of dural receptive fields but not significant decrease in ongoing activity. Microinjection of lidocaine but not saline into the trigeminal ganglion was followed by a substantial decrease in both the receptive field size and the activity of the recorded WDR units. Mechanical insensitivity of receptive fields after trigeminal ganglion blockade was accompanied by the disappearance of ongoing activity. We conclude that the ongoing activity of WDR neurons in the spinal trigeminal nucleus, which may be indicative for processes of sensitization, is driven remotely by ongoing afferent input.     

Cannabinoid and vanilloid effects of R(+)-methanandamide in the hemisected meningeal preparation

The endogenous cannabinoid R(+)-methanandamide (mAEA) exerts differential anti- and pronociceptive effects by activating both cannabinoid (CB1) and vanilloid (TRPV1) receptors of nociceptive primary afferents. The significance of these effects in meningeal nociception was evaluated by modulation of calcitonin gene-related peptide (CGRP) release from meningeal afferents measured in an in vitro preparation of the hemisected rat skull. Temperature steps to 39 degrees C and 45 degrees C caused heat-dependent increases in CGRP release. One micromolar mAEA inhibited CGRP release at 32 degrees C but facilitated it at 45 degrees C. This effect was abolished in the presence of the TRPV1 receptor antagonist capsazepine. Lower doses of mAEA had no effect on basal or heat-evoked release. In the presence of the CB1 receptor antagonist SR141716 (0.2 microm) heat-stimulated increase in CGRP release was facilitated. CGRP release in the presence of SR141716 (0.2 microm) was further increased by adding mAEA at a concentration which had no effect on its own. These results confirm an opposing functional role for anandamide at CB1 and TRPV1 receptors on meningeal afferents.