Trigeminal neurosensory changes following acute and chronic paranasal sinusitis.

OBJECTIVE: The aim of this study was to document sensory changes in the supraorbital, infraorbital, and mental nerve distributions following acute and chronic maxillary and frontal sinusitis. METHOD AND MATERIALS: Seven patients with a total of 14 infected sinuses were included in the study. Neurosensory function was evaluated by measuring the electrical detection threshold for large myelinated nerve fibers and heat detection thresholds for the assessment of the thin unmyelinated nerve fibers. The sensory tests were conducted in the infraorbital, supraorbital, and mental dermatomes. Patient evaluation included clinical examination and computerized tomographic imaging of the sinuses. Sinusitis symptoms of 1 month or less were considered acute, and symptoms that persisted for more than 3 months were considered chronic. Detection thresholds in 8 healthy volunteers served as controls. RESULTS: Eight acute and 6 chronic sinusitis cases were diagnosed. Acute sinusitis produced bilateral large myelinated fiber hypersensitivity (electrical) relative to healthy controls, with no significant change in the thin unmyelinated nerve fiber detection threshold (thermal). Chronic sinusitis resulted in large myelinated fiber hyposensitivity and thin myelinated fiber bilateral hyposensitivity, as compared to healthy controls. CONCLUSIONS: This study concurs with previous studies in finding that early inflammatory neuritis can produce large myelinated nerve fiber hypersensitivity, while long-lasting processes, presumably accompanied with early nerve damage, may result in hyposensitivity.     

Ultrastructural characteristics of axons in traumatic neuromas of the human lingual nerve

AIMS: To determine the ultrastructural characteristics of axons in traumatic neuromas of the human lingual nerve during the surgical removal of lower third molar teeth and to establish whether any characteristics were different between patients with dysesthesia and patients without dysesthesia. METHODS: Transmission electron microscopy was used to determine the ultrastructural morphological characteristics of human lingual nerve neuromas (n = 34) removed at the time of microsurgical nerve repair. From a sample population of myelinated and nonmyelinated fibers within the neuromas, fiber diameter, myelin thickness, g-ratio, and the number of mitochondria per axon were quantified. Comparisons were made with normal control lingual nerve specimens (n = 8) removed at the time of organ donor retrieval. RESULTS: Significant differences in ultrastructural morphology were found between the neuromas and control nerves. The neuromas contained a higher proportion of small (2- to 8-microm diameter) myelinated nerve fibers than controls, and the mean myelinated fiber diameter was significantly lower in neuromas than in controls. Mean myelin sheath thickness was significantly thinner in neuromas (0.6 +/- 0.1 microm) than in controls. However, the g-ratio, which is a measure of the myelination status of the nerve fibers in relation to their diameter, was found to be similar in each group, suggesting a normal process of myelination in the damaged axons. Nonmyelinated axon diameter was also significantly smaller in the neuromas than in the controls, and Schwann cells were found to sheathe more nonmyelinated axons in neuromas than in controls. The ratio of nonmyelinated to myelinated axons was significantly higher in neuromas than in controls. However, no significant differences were found between patients with dysesthesia and those without dysesthesia. CONCLUSION: Damage to the lingual nerve results in marked changes to axon diameter, myelin sheath thickness, and Schwann cell-axon relationships. These ultrastructural changes could contribute to the altered electrophysiological properties of axons trapped within neuromas. However, no significant differences in the ultrastructural characteristics studied were found between specimens from patients with or without symptoms of dysesthesia.     

大鼠正畸压力侧牙周膜神经纤维超微结构变化的研究

目的：观察正畸力作用下压力侧牙周膜神经纤维超微结构的改变。方法：利用透射电镜观察15只大鼠正畸牙齿移支2d、1周、2周和3周后，压力侧牙周膜神经纤维超微结构的改变。结果：牙齿移动2d后可见粗有髓神经纤维变性，3周后尚未完全恢复。细无髓神经纤维在2d时数量稍增多，1周时达到高,逐渐减少，至3周时数恢复 正常，部分神经纤维轻度变性；细有髓神经纤维数量无明显变化，其中部分神经纤维轻度变化性。结论：在正畸力作用下，牙周膜神经纤维均发生不同程度的变化，Aβ纤维严重变性，而Aδ纤维及C纤维轻度变性，C纤维主要表现为增生。     

Ultrastructure and degeneration analysis of the nerve fibres of the tooth pulp in the cat

An attempt was made to distinguish somatic sensory nerve fibres from autonomic postganglionic sympathetic nerves in tooth pulp by secondary degeneration. Pulps were compared after transection of the inferior alveolar nerve, after extirpation of the superior cervical sympathetic ganglion and after both operations performed at the same time (total neural isolation). About 15 per cent of the nerves in normal feline pulps were myelinated and about 85 per cent unmyelinated. Only 1.5 per cent contained granular vesicles 30–50 nm or 80–120 nm in diameter. After transection of the alveolar nerve, all myelinated as well as some unmyelinated fibres degenerated. Degenerated fibres contained no vesicles. After extirpation of the ganglion, only a few degenerating unmyelinated fibres were observed; some contained 80–100 nm diameter granular vesicles. Two months after total neural isolation, the pulp contained no nerve fibres.     

Quantitation of nerve fibres in the primary and permanent canine and incisor teeth in man.

Myelinated and unmyelinated nerve fibres were counted and myelinated axons were measured in juxta-apical cross-sections of human primary and permanent canines and incisors. Fully-developed human primary canines had significantly more myelinated axons than permanent canines, but the number of unmyelinated axons was similar. Permanent incisors had significantly more myelinated nerve fibres entering the apex than did primary incisors, but the number of unmyelinated nerve fibres was similar. Primary canines and incisors lost nerve fibres early during resorption; evidence of degenerating myelinated axons was scant. A significant linear correlation existed between numbers of myelinated and unmyelinated axons for primary incisors and canines. The myelinated axon circumference was similar for primary and permanent teeth. Permanent teeth tended to have smaller groups of unmyelinated axons.     

Proposal for a standardized protocol for the systematic orofacial examination of patients with Hereditary Sensory Radicular Neuropathy

AIM: To apply a standardized protocol for the orofacial evaluation of two adult siblings (one male and one female) with Hereditary Sensory Radicular Neuropathy (HSRN) that presented with dental problems. SUMMARY: The systematic evaluation consisted of (a) clinical questionnaire; (b) radiographs [orthopantomography and computarized tomography (CT)]; (c) orofacial psychophysical tests (pain, thermal, mechanical and electrical sensation); and (d) histology of gingiva and pulp (optical and transmission electronic microscopy). The female patient had complete insensitivity to orofacial pain and partial facial heat sensitivity, and received dental treatment without anaesthesia or pain. She had a severe and painless jaw infection due to pulp necrosis in tooth 37. The male patient had partial insensitivity to orofacial pain and required anaesthesia for dental treatment. Histological examination of gingivae and pulpal tissue revealed an altered proportion of unmyelinated and myelinated sensory nerve fibres. KEY LEARNING POINTS: * Patients with HSRN may present with significant, silent dental disease. * A standard protocol is helpful when evaluating such patients. * If the opportunity arises, evaluation of pulp tissue may reveal an altered proportion of myelinated and unmyelinated nerve fibres. This may avoid the more estabilished sural nerve biopsy.     

干细胞局部应用对缺损面神经再生效果的系统评价

目的 系统评价干细胞对面神经缺损的修复效果。方法 在Pubmed、Cochrane Library、Web of Science、Embase、Scopus及中国生物医学文献数据库检索关于评价干细胞对动物面神经再生效果的所有原始研究,2名专业人员独立完成文献筛选、数据提取及偏倚风险评估。使用RevMan 5.3软件及随机效应模型进行统计分析,分析结果以均数差（MD）及95%可信区间（CI）的形式呈现。对面神经的功能性评估（胡须运动评分、面瘫评分）及组织学评估（有髓纤维密度、纤维直径、髓鞘厚度、G比值）结果进行Meta分析。结果 从6个数据库共检索出4 614篇文献,15篇被纳入了Meta分析。干细胞组的胡须运动评分、面瘫评分、有髓纤维密度、髓鞘厚度均高于非干细胞组（P<0.05）,G比值小于非干细胞组（P=0.001）,纤维直径二者无统计学差异（P=0.08）。结论 干细胞具有促进面神经再生的潜能。     

Effect of anhydrous glycerol injection into the mental foramen of rabbit on inferior nerve:An experimental study]

In this experiment anhydrous glycerol was injected into the mental foramen of rabbits to determine neurolytic effects on the peripheral trigeminal nerve by electrohysiologic and morphologic methods.The rabbits underwent unilateral injection of anhydrous glycerol and the control side was injected with normal saline.The results show that partial fibers are effected (myelinated and unmyelinated fibers at random).Glycerol injection increased the average latencies and reduced the average amplitudes of compound action potentials.Morphologic examination disclosed myelin swelling,disintergrationan d axonal shrinking,axonolysis.One week after the injection,eletrophysiologic and morphologic changes were most severe and signs of regeneration were noted in the fifth week,By 16 weeks after injection,the nerve fibers appeared almost normal.     

Morphology of neural endings in the human periodontal ligament: An electron microscopic study

The ultrastructure of sensory nerve endings in the human periodontal ligament from 43 extracted teeth was studied using serial sections. Three types of nerve endings were found: free nerve endings (FNE), Ruffini-like endings and lamellated corpuscles. Free nerve endings stem from unmyelinated or from myelinated nerve fibers. The endings contain neurotubuli, neurofilaments and vesicles. Ruffini-like receptors were mostly found in the apical part of the periodontal ligament. In these Ruffini-like receptors a particularly abundant concentration of mitochondria appears. In some cases desmosome-like junctions are present between neurite and ensheathing cell. Lamellated corpuscles were also found in the periodontal ligament. The lamellae are extremely endocytotic and are in close contact with each other.     

Immunohistochemical evidence for ATP receptors in human dental pulp

Evidence is accumulating which supports a role for ATP in the initiation of pain by acting on P2X receptors, in particular P2X3, expressed on nociceptive afferent nerve terminals. To investigate whether this receptor plays a role in dental pain, we studied the presence and distribution of P2X3 receptors in human dental pulp, and their co-localization with other neural markers. Pulps were removed from extracted third molars and immunohistochemically stained with an antibody against P2X3 receptors. P2X3 immunoreactive (-ir) nerve fibers were detected in the main body of the pulp, in the sub-odontoblastic plexus of Raschkow, and within the odontoblastic area. Co-localization of the P2X3-ir neurons with neurofilament protein (NF) showed that the majority of the fibers were positive for both NF and P2X3. Double labeling with isolectin B4 (IB4) showed that all P2X3-ir neurons also bind IB4. We conclude that P2X3 receptors are present on both myelinated and unmyelinated nerve fibers in human dental pulp and may play a role in dental pain mechanisms.     

脂质体阿霉素对大鼠三叉神经形态与功能影响的实验研究

目的 :观察脂质体阿霉素对大鼠三叉神经形态与功能的影响。方法 :3 3g/L脂质体阿霉素直接注射于大鼠一侧眶下神经束 ,对侧以生理盐水对照。神经电生理检查给药后大鼠的二腹肌肌电的变化 ,光镜下观察实验侧三叉神经节细胞的形态学变化 ,透射电镜观察三叉神经节细胞的超微形态结构变化。结果 :神经电生理结果显示动物对针刺反应不敏感 ,并显示不同时间左右两侧潜伏期 (ms)及痛阈 (mA)的变化都有显著性差异 (P <0 .0 5 ) ;实验侧光镜下可见大量细胞皱缩 ,形态不规则 ,细胞周围出现空隙 ;电镜下可见胞质中出现不规则的电子致密物质 ,线粒体、高尔基体、粗面内质网、核膜、有髓神经纤维髓鞘和无髓神经纤维病理性改变。结论 :脂质体阿霉素注入神经干后 ,可以选择性破坏相应的节细胞 ,引起神经功能上的变化。     

Innervation of human periodontium I. Classification of periodontal receptors

A bstract — The neural tissue in human periodontium is associated with the terminal part of a norve trunk from which myelinated nerve fibres leave and in some instances divide into three or more nerve fibres.
Encapsulated myelinated nerve fibres lose their myelin sheaths and encircle the adjacent myelinated nerve fibres to form compound meehanoreceptors approximately 35 × 45 μm. Simple mechanoreceptors of approximately 10 × 10 μm consisted of single myelinated nerve fibres surrounded by cell bodies and terminated as encapsulated unmyelinated nerve fibres. A cluster of compound mechanoreceptors formed a complex approximately 100times 150 μm.
An arterial system appeared to supply nutrition for the compound receptors, whilst an arcade of veins surrounded the neural complex.     

Changes in the fine structure of the dental pulp in human caries pulpitis

Abstract. Electron microscopic investigation of human pulps manifesting caries pulpitis revealed degenerative changes in myelinated and unmyelinated nerves and blood vessels. The degenerative changes noted in nerves were generally less severe and less frequent than those noted in the blood vessels and surrounding pulp tissue. This was attributed to the presence of an abundance of collagen fibers about the nerve bundles and nerve axons. The degenerative changes in the blood vessels ranged from minor changes in endothelial cell morphology to complete necrosis and lysis. These changes were generally accompanied by alterations in the integrity of the basement membrane. Advanced changes in blood vessels of the pulp appeared to result in an increase in vascular permeability causing edema. It was suggested that some of the degenerative changes noted might be related to the humoral phase of the inflammatory response.     

Delta (delta) opioid receptors in small and medium-sized trigeminal neurons supporting the dental pulp of rats

The control of pain perception is a challenge in clinical dentistry, most prominent during tooth pulp inflammation. The tooth pulp is a well-defined target, and is densely supplied by a sensory trigeminal innervation. Opioids are signaling molecules that are suggested to participate in pain perception. Here we analysed the presence of delta opioid receptor (DOR) in trigeminal neurons innervating the tooth pulp of rat molars. Immunohistochemical and ultrastructural analysis revealed that DOR was identified in peripheral nerves in the molar dental pulp, both in the root and the coronal pulpal parts, with branching in the highly innervated subodontoblast layer. DOR was localised in about one third of all the trigeminal dental neurons, identified by means of retrograde neuronal transport of fluorogold (FG) from the dental pulp. Of the DOR-labeled neurons, nearly all were small and medium-sized (147.5-1,810.2 microm(2), mean 749.1 +/- 327.3 microm(2)). Confocal microscopy confirmed that DOR-immunoreactivity was distributed as granules in the neuronal cytoplasm. Approximately 70% of the DOR-immunoreactive neurons were also immunopositive for vanilloid receptor 1 (TRPV1). Ultrastructural analysis demonstrated DOR-immunoreactivity in the unmyelinated and in some of the myelinated nerve fibers in the dental pulp. These results indicate that DOR may influence the function in a subset of small and medium-sized trigeminal sensory neurons supporting the tooth, which are mainly known for their ability to mediate nociceptive stimuli. Agonists, acting on DOR, may thus have an influence on a subpopulation of nociceptive neurons supporting the rat tooth.     

Response properties of pulpal nerve fibers with different conduction velocities

Tapering and branching of the nerve fibers cause the conduction velocity (CV) along the axon to be unequal. The purpose of this study was to investigate the response properties of the myelinated and unmyelinated nerve fibers in the cat tooth pulp. Electrophysiological recordings were made from the functional single fibers innervating the lower canine tooth pulp in 25 adult cats anesthetized with pentobarbital sodium after the application of four types of stimuli to the canine tooth. A total of 272 single pulpal nerve fibers was identified. A-fibers (n = 215) were divided into two groups: One (Ac, n = 55) consisting of the fibers whose intrapulpal CVs were less than 2 m/s and the extra-pulpal CVs of more than 2 m/s, and the other (At, n = 160) consisting of the fibers whose CVs were more than 2m/s both inside and outside the tooth pulp. Fifty-seven C-fibers (C) were also found. None of C, 47% of At and 46% of Ac responded to the rapid elevation of the temperature. None of At, 38% of Ac and 53% of C responded to the continuous heat. None of C, 20% of At and 20% of Ac responded to the hydrostatic pressure. None of At, 86% of Ac and all of C responded to bradykinin. These results suggest that the functional difference between the pulpal A-and C-fibers is not clear and that the Ac-fibers may complicate the dental and pulpal pain.     

Anatomic-histologic survey of the sural nerve: implications for inferior alveolar nerve grafting

An anatomic and histologic study of the sural nerve was made as part of an effort to formulate a rationale governing selection of appropriate segments of the nerve as a donor graft for repair of the inferior alveolar nerve. Ten sural nerves were obtained by dissection at autopsy and their topography assessed. Hematoxylin and eosin stained transverse sections were prepared from samples taken at 32 locations along each nerve. Nerve diameter and shape, fascicle number, and fascicular arrangement were assessed at low power using light microscopy. It was concluded that technical objectives of graft repair can be better attained by selective sural nerve harvest.     

神经生长因子对下齿槽神经再生影响的实验研究

目的 探讨外源性神经生长因子（ｎｅｒｖｅ ｇｒｏｗｔｈ ｆａｃｔｏｒ,ＮＧＦ）对成年大白兔下齿槽神经再生的影响。方法 选用２４只成年日本大耳白兔,在双侧下齿槽神经各造成８ｍｍ缺损,神经近远端用硅胶管桥接,右侧硅小室 内注入外源性ＮＧＦ 作实验侧,左侧注入生理盐水为对照侧。对实验侧和对照侧的再生有髓神经纤维数目、传导速度、纤维横断面积和髓鞘厚度作相应比较。结果 ①ＮＧＦ能使有髓神经纤维数目明显增加;     

Transplantation of cultured bone marrow stromal cells to improve peripheral nerve regeneration

The role of cultured bone marrow stromal cells (BMSCs) in peripheral nerve regeneration was examined using an established rabbit peroneal nerve regeneration model. A 15-mm peroneal nerve defect was bridged with a vein filled with BMSCs (1 x 10(6)), which had been embedded in collagen gel. On the contralateral side, the defect was bridged with a vein filled with collagen gel alone. When the regenerated tissue was examined 4, 8 and 12 weeks after grafting, the number and diameter of the myelinated fibers in the side with the BMSCs were significantly higher than in the control side without the BMSCs. This demonstrates the potential of using cultured BMSCs in peripheral nerve regeneration.     

Congenital insensitivity to pain (hereditary sensory and autonomic neuropathy type V): a rare case report

Congenital insensitivity (HSAN) to pain is a rare disorder, which affects the body's painprotective mechanism and predisposes the patient to increased risk and incidence of traumatic injuries. Currently, 5 types of hereditary sensory and autonomic neuropathies have been identified, depending upon different patterns of sensory and autonomic dysfunction, peripheral neuropathy, clinical features, and genetic abnormalities. The purpose of this report is to present the case of a 10-year-old boy with congenital insensitivity to pain (hereditary sensory autonomic neuropathy [HSAN] type V) with dental implications. History, clinical features, nerve conduction studies, and electron microscopy revealed no reaction to painful stimuli, a self-mutilating habit, multiple missing teeth, and an absence of small, unmyelinated fibers, thus indicating HSAN type V. Management included patient counseling and use of a mouthguard to prevent further damage and restore function.     

Galanin-immunoreactive nerve fibers in the periodontal ligament during experimental tooth movement

Neuropeptides have been suggested to play a role in pain transmission during orthodontic tooth movement. We examined this hypothesis by examining the effect of orthodontic tooth movement on the expression of galanin (GAL)-immunoreactive (ir) nerve fibers in the periodontal ligament (PDL) of one mesial root (MR) and two distal roots (DRs) of the rat maxillary first molar. In control rats, GAL-ir fibers were very rare in the PDL. One day after the insertion of the elastic band, the number of GAL-ir fibers increased, becoming most numerous at 3 days. From 5 to 28 days, GAL-ir fibers tended to decrease. Electron microscopic observation showed that all of the GAL-ir fibers were unmyelinated. These findings suggest that GAL-containing nerve fibers in the PDL may play an important role in the response of the tissue to experimental tooth movement.