Trigeminal neuropathy

Trigeminal neuropathies (TNs) are well recognized disorders characterized and manifesting as skin and mucosal numbness in the region innervated by the trigeminal nerve. Facial numbness indicates trigeminal sensory alteration affecting the trigeminal system. TNs always pose differential location difficulties as multiple diseases are capable of producing them: they can be the result of traumatism, tumors, or diseases of the connective tissue, infectious or demyelinating diseases, or may be of idiopathic origin. Their importance is explained by the fact that TN may represent the first manifestation of tumor disease, or of relapse in patients with prior neoplastic processes. As such, these manifestations are ominous, and patient life expectancy is often short. The clinical exploration reveals a loss of sensitivity in the cutaneous territory corresponding to the affected nerve, which can be partial (hypoesthesia) or complete (anesthesia). The sensory defect is occasionally associated with hyperesthesia (i.e., the patient suffers a decrease in sensory perception, but when sensation is perceived, it may cause considerable discomfort). Complementary studies are needed to establish the etiologic diagnosis, with laboratory tests to discard the possible causative diseases underlying the trigeminal neuropathy, and the opportune radiographic examinations in the form of plain X-rays or a routine cranial computed tomography scan.     

Trigeminal Neuralgia. Clinical Manifestations of First Division Involvement

A series of 19 patients with what originally had been diagnosed as a first division (V₁) trigeminal neuralgia was collected. The inclusion criteria were severe, rather short-lasting pain attacks within the V₁ area, combined with trigger mechanisms. There were 10 women and 9 men, and the mean age of onset was 57.8 years. Fifteen of 16 with adequate information on attack duration had paroxysms of a "few seconds'" duration or less, whereas 10 patients had paroxysms lasting ≥2 seconds. In an exceptional case, only "more long-lasting" attacks (greater than 30 seconds' duration) were experienced.
In regard to autonomic phenomena, lacrimation was most frequently present (in a total of 8 patients; 3 rather regularly, 5 more irregularly). The combination of lacrimation, conjunctival injection, and rhinorrhea was present in only 2 (of 19), and in neither of them in a major way. Typically, autonomic phenomena occurred during the later stages of disease and during particularly severe and long-lasting attacks. Seven of 14 with adequate information also had nocturnal attacks. Initially, a more or less complete carbamazepine effect was reported by 10 of 13 patients. Precipitation mechanisms were the same as with second and third division tic, but were mainly located within the V₁ area, particularly initially.
A comparison with SUNCT syndrome has been made. SUNCT is a predominantly male disorder, with only exceptional attacks of ≥10 seconds' duration, and generally with attacks of 15 seconds or longer. Autonomic symptoms and signs are more pronounced than in V₁ tic. Carbamazepine generally provides minor, if any, benefit in SUNCT. The present work strongly indicates that the two disorders are essentially different.     

三叉神经慢性缩窄环术后大鼠行为反应与组织学变化的关系

目的:观察慢性缩窄环术前后大鼠对机械刺激的反应阈值与三叉神经的组织学改变,探讨三叉神经痛的发病机制,为治疗等提供实验基础。方法:在大鼠一侧三叉神经分支眶下神经(ION)行缩窄环术(CCI),观察术后不同时段大鼠对机械刺激的反应阈值及三叉神经组织学改变。结果:1.术后2周到8周,在ION支配区域内,大鼠出现痛觉超敏现象,与术前及对照组比较存在显著差异(P<0.01),术后4周开始逐渐恢复,术后12周左右恢复至术前水平。2.术后2周,I0N-CCI区域神经纤维肿胀,髓鞘脱失,正常结构消失;术后4到8周,神经纤维仍有脱髓鞘改变;术后12周神经纤维密度均匀,髓鞘与轴突比例恢复正常。结论:慢性缩窄环术后大鼠对机械刺激的反应阈值与其局部神经纤维脱髓鞘改变密切相关。     

三叉神经鞘瘤的诊断和显微外科治疗策 略简

目的探讨三叉神经鞘瘤的诊断及治疗策略。方法回顾性分析41例三叉神经鞘瘤的病例资料。最常见症状为面部麻木或感觉减退。按肿瘤位置分为5型：颅中窝型3例,颅后窝型8例,颅中后窝哑铃型26例,颅中窝颅外型2例,颅中后窝颅外型2例。采用额颞硬膜外入路13例,颞底经天幕入路14例,乙状窦后入路11例,乙状窦前入路3例。结果肿瘤全切35例,次全切除5例,大部分切除1例。随访13例,时间3～84个月,复发2例。结论影像学检查对三叉神经鞘瘤诊断具有重要意义。个体化手术入路可获得满意的切除程度和较少并发症。     

原发性三叉神经痛伽玛治疗后面部感觉异常情况分 析简

目的分析伽玛刀治疗原发性三叉神经痛病人面部感觉异常发生率及其与疼痛缓解间的关系。方法回顾性分析45例接受伽玛刀治疗并有完整随访的原发性三叉神经痛病例资料,记录和分析疼痛控制效果、起效时间以及面部感觉异常等并发症发生情况。结果中位随访时间15个月（12～37个月）。术后初始疼痛缓解BNIⅠ级15例（33-3％）,Ⅱ级13例（28．9％）,Ⅲ级8例（17．8％）,Ⅳ级5例（11．1％）,Ⅴ级4例（8．9％）;伽玛刀治疗整体有效率为80％。至最后一次随访,复发6例（13.3％）,（初始疼痛缓解为BNII级3例,Ⅲ级3例）;平均复发时间11．7个月（5～18个月）。伽玛刀治疗后新发面部感觉异常17例（37．8％）,疼痛完全缓解者新出现面部感觉异常的比例明显高于部分缓解或疗效不佳者（P〈0．05）。结论伽玛刀是有效的三叉神经痛治疗方法．术后面部感觉异常发生可能与更好的疼痛缓解相关。     

基于DTI的三叉神经痛脑白质结构异常及其与临床特征的相关性

目的 采用基于纤维束的空间统计方法（TBSS）探讨原发性三叉神经痛（PTN）患者脑白质微结构异常。方法 对38例PTN患者（PTN组）和38名年龄、性别匹配的健康志愿者（对照组）行全脑DTI扫描,并用FSL软件进行分析,寻找FA值、平均扩散系数（MD）、径向扩散系数（RD）和轴向扩散系数（AD）存在组间统计学差异的脑区,并与视觉模拟评分（VAS）进行相关分析。结果 与对照组相比,PTN组胼胝体、放射冠、左侧上纵束、左侧下纵束及下额枕束FA值降低;且PTN组双侧丘脑后辐射、双侧内囊、双侧外囊、穹窿、右侧上纵束同时存在MD值和RD值升高,而AD升高脑区仅局限于双侧内囊前支、左侧内囊后支、双侧上放射冠和双侧上纵束。PTN患者左侧上纵束FA值与VAS呈负相关（r=-0.502,P=0.001）,左侧上纵束MD值与VAS评分呈正相关（r=0.437,P=0.006）。结论 丘脑、内囊MD值和RD值同向升高而不伴FA值降低可能是PTN的相对特征性DTI表现;左侧上纵束FA值和MD值对评估PTN患者疼痛水平有参考价值。     

磁共振在诊断三叉神经痛及面肌痉挛中成像序列的选择

目的：对磁共振应用常规及特殊成像序列诊断三叉神经痛（TN）及面肌痉挛（Fs）的价值进行评价。方法：TN及Fs患者52例,行SET1WI、T2WI扫描,排除占位后再行3D—TSE序列和3D—VIBE序列扫描。经3DMRP、MIP、min—MIP后处理图像,观察神经与周围血管的关系。结果：16例TN和8例FS为肿瘤引起,行切除术：23例TN和5例FS为血管压迫所致,行微血管减压术。3D—VIBE、3D—TSE序列综合判断血管压迫性三叉神经痛及面肌痉挛的阳性预测值、阴性预测值、敏感性、手术符合率分别为92％（23／25）、33．3％（1／3）、96％（24／25）、85．7％（24／28）。结论：磁共振扫描对明确三叉神经痛及面肌痉挛的病因具有重要价值,3D—TSE序列和3D—VIBE序列是显示血管神经空间关系的敏感方法．对TN和FS的术前评估具有较高的价值。     

Optimal duration of percutaneous microballoon compression for treatment of trigeminal nerve injury简

Percutaneous microballoon compression of the trigeminal ganglion is a brand new operative technique for the treatment of trigeminal neuralgia. However, it is unclear how the procedure mediates pain relief, and there are no standardized criteria, such as compression pressure, compression time or balloon shape, for the procedure. In this study, percutaneous microballoon compression was performed on the rabbit trigeminal ganglion at a mean inflation pressure of 1,005 ± 150 mmHg for 2 or 5 minutes. At 1, 7 and 14 days after percutaneous microballoon compression, the large-diameter myelinated nerves displayed axonal swelling, rupture and demyelination under the electron microscope. Fragmentation of myelin and formation of digestion chambers were more evident after 5 minutes of compression. Image analyzer results showed that the diameter of trigeminal ganglion cells remained unaltered after compression. These experimental findings indicate that a 2-minute period of compression can suppress pain transduction. Immunohistochemical staining revealed that vascular endothelial growth factor expression in the ganglion cells and axons was significantly increased 7 days after trigeminal ganglion compression, however, the changes were similar after 2-minute compression and 5-minute compression. The upregulated expression of vascular endothelial growth factor in the ganglion cells after percutaneous microballoon compression can promote the repair of the injured nerve. These findings suggest that long-term compression is ideal for patients with recurrent trigeminal neuralgia.     

Neurotrophic Proteins in Dentin and Their Effect on Trigeminal Sensory Neurons

IntroductionA plethora of bioactive molecules present during tooth formation become sequestered in the mineralized dentin matrix and can be released into the pulp tissue after demineralization from carious lesions. However, neurotrophic factors are differentially expressed and secreted during various stages of odontogenesis. Thus, the aims of this study were(1) to investigate their presence and relative abundance in crown and root dentin and(2) to evaluate the bioactivity of dentin-derived proteins on neuronal cells.MethodsDentin matrix proteins (DMPs) were isolated from matched roots and crowns of extracted healthy human third molars. The total protein amount as well as the concentration of growth factors and neurotrophic proteins were quantified. The impact on neuritogenesis was determined with mouse trigeminal neurons in vitro and by a hydrogel implant model in vivo. Transient receptor potential cation channel subfamily V member 1 (TRPV1) sensitization of DMP-conditioned neurons was evaluated by single-cell calcium imaging.ResultsThe relative concentration of neurotrophic molecules revealed that nerve growth factor is the most abundant neurotrophin with 3-fold increased expression in radicular dentin. Similarly, brain-derived neurotrophic factor and neurotrophin 3 are more abundant in radicular than coronal dentin. Conversely, glial cell line–derived neurotrophic factor is more abundant in coronal dentin, whereas neurotrophin 4 is equally distributed. Dentin matrix proteins promoted neurite outgrowth in vitro and axonal targeting in vivo, with a greater effect observed by radicular dentin extracts. Furthermore, DMPs sensitized TRPV1 responses in mouse trigeminal neurons with greater activity seen with extracts from root dentin.ConclusionsNeurotrophic factors are differentially distributed between coronal and radicular dentin with different effects of dentin-derived proteins on axonal growth and targeting as well as the sensitization of TRPV1. Thus, extracellular proteins from the dentin matrix are likely involved in neurogenic responses to caries and could be exploited in clinical regenerative endodontics to promote reinnervation and enhance tissue regeneration.