Cellular Localization of Aquaporin-1 in the Human and Mouse Trigeminal Systems

Previous studies reported that a subpopulation of mouse and rat trigeminal neurons express water channel aquaporin-1 (AQP1). In this study we make a comparative investigation of AQP1 localization in the human and mouse trigeminal systems. Immunohistochemistry and immunofluorescence results showed that AQP1 was localized to the cytoplasm and cell membrane of some medium and small-sized trigeminal neurons. Additionally, AQP1 was found in numerous peripheral trigeminal axons of humans and mice. In the central trigeminal root and brain stem, AQP1 was specifically expressed in astrocytes of humans, but was restricted to nerve fibers within the central trigeminal root and spinal trigeminal tract and nucleus in mice. Furthermore, AQP1 positive nerve fibers were present in the mucosal and submucosal layers of human and mouse oral tissues, but not in the muscular and subcutaneous layers. Fluorogold retrograde tracing demonstrated that AQP1 positive trigeminal neurons innervate the mucosa but not skin of cheek. These results reveal there are similarities and differences in the cellular localization of AQP1 between the human and mouse trigeminal systems. Selective expression of AQP1 in the trigeminal neurons innervating the oral mucosa indicates an involvement of AQP1 in oral sensory transduction.     

Percutaneous Radio-Frequency Rhizotomy in the Treatment of Trigeminal Neuralgia

A percutaneous technique of selective partial trigeminal root coagulation was evaluated in the treatment of 38 patients suffering from trigeminal neuralgia, 1 patient with pain secondary to oral carcinoma and 1 patient with atypical facial pain. The pain of trigeminal neuralgia was relieved in 94.7 percent of patients. Pain was relieved in the patient with oral carcinoma, but not in the patient with atypical facial pain. There was no mortality and no permanent morbidity outside of the trigeminal nerve lesion. The procedure requires only a brief hospital stay without the time, expense and hazards of open cranial surgical procedures.     

Trigeminal Neuralgia and Dental Malocclusions

Out of 39 patients with intractable trigeminal neuralgia seven have had continuing relief for over three years after dental treatment. Five out of six recent consecutive edentulous patients had immediate improvement. More radical treatment, such as ganglion injection or nerve root section, has been at least postponed.     

Trigeminal and facial innervation of cirri in three teleost species

Summary Innervation of the cirri in three teleost species (Hypsoblennius gilberti, Hypsoblennius gentilis, Oxylebius pictus) was investigated with the use of HRP- and cobalttracing techniques. All projections were found to be ipsilateral. Labeled cells were demonstrated in both portions of the trigeminal ganglion and in the facial ganglion. Cirrus nerve fibers running in the trigeminal nerve project to terminal fields in an isthmic sensory trigeminal nucleus, to areas adjacent to the descending trigeminal root in the brainstem, and to the medial funicular nucleus in the medulla. Distribution of labeled cells in the trigeminal ganglion complex suggests a functional distinction of the two ganglion portions. Cirrus nerve fibers belonging to the facial nerve terminate in a circumscribed part of of the facial lobe, indicating a somatotopic projection. Pathways were principally the same in all three species investigated. Findings of facial innervation of teleost cirri suggest a suspected gustatory function of teleost head appendages.     

Trigeminal primary afferent projections to the spinal cord of the frog,Rana ridibunda

The distribution in the spinal cord of the trigeminal primary projections in the frog Rana ridibunda was studied by means of the anterograde transport of horseradish peroxidase (HRP). Upon entering the medulla via the single trigeminal root, a conspicuous descending tract that reaches the cervical spinal cord segments is established. This projection arises in the ophthalmic (V1), maxillary (V2), and mandibular (V3) trigeminal nerve subdivisions. In the spinal cord, only a minor somatotopic arrangement of the trigeminal fibers was observed, with the fibers arising in V3 terminating somewhat more medially than those from V1 and V2. A dense projection to the medial aspect of the spinal cord, above the central canal, primarily involves V3. Each trigeminal branch sends projections at cervical levels to the contralateral dorsal field, and those from V2 are most abundant. Bilateral experiments with HRP application show convergence of primary trigeminal and spinal afferents within the dorsal field of the spinal cord. The pattern of arrangement of the trigeminal primary afferent fibers in the spinal cord of this frog largely resembles that of amniotes. However, the organization seems simpler and the slight somatotopic distribution of V1, V2, and V3 fibers is similar to the condition in other anamniotes. © 1993 Wiley-Liss, Inc.     

Transient Receptor Potential Channels Encode Volatile Chemicals Sensed by Rat Trigeminal Ganglion Neurons

Primary sensory afferents of the dorsal root and trigeminal ganglia constantly transmit sensory information depicting the individual’s physical and chemical environment to higher brain regions. Beyond the typical trigeminal stimuli (e.g. irritants), environmental stimuli comprise a plethora of volatile chemicals with olfactory components (odorants). In spite of a complete loss of their sense of smell, anosmic patients may retain the ability to roughly discriminate between different volatile compounds. While the detailed mechanisms remain elusive, sensory structures belonging to the trigeminal system seem to be responsible for this phenomenon. In order to gain a better understanding of the mechanisms underlying the activation of the trigeminal system by volatile chemicals, we investigated odorant-induced membrane potential changes in cultured rat trigeminal neurons induced by the odorants vanillin, heliotropyl acetone, helional, and geraniol. We observed the dose-dependent depolarization of trigeminal neurons upon application of these substances occurring in a stimulus-specific manner and could show that distinct neuronal populations respond to different odorants. Using specific antagonists, we found evidence that TRPA1, TRPM8, and/or TRPV1 contribute to the activation. In order to further test this hypothesis, we used recombinantly expressed rat and human variants of these channels to investigate whether they are indeed activated by the odorants tested. We additionally found that the odorants dose-dependently inhibit two-pore potassium channels TASK1 and TASK3 heterologously expressed In Xenopus laevis oocytes. We suggest that the capability of various odorants to activate different TRP channels and to inhibit potassium channels causes neuronal depolarization and activation of distinct subpopulations of trigeminal sensory neurons, forming the basis for a specific representation of volatile chemicals in the trigeminal ganglia.     

Mesencephalic root fibers of the trigeminal nerve in the cat

The trigeminal nerve has three motor roots and one sensory root in the cat. One of the motor roots can be divided into two bundles: the larger and the smaller. These motor roots form the common root with the sensory root at the exit from the pons, sometimes being separated partially by the subarachnoidal space between the medial and the ventral part of the common root. The mesencephalic root fibers are observed numerously in all the motor roots. Some degenerated fibers are observed in the sensory root. The transitional zone of the trigeminal nerve root between central and peripheral nervous system is occupied by interlocking processes of the fibrous astrocyte.     

SCN2B in the Rat Trigeminal Ganglion and Trigeminal Sensory Nuclei

The beta-2 subunit of the mammalian brain voltage-gated sodium channel (SCN2B) was examined in the rat trigeminal ganglion (TG) and trigeminal sensory nuclei. In the TG, 42.6 % of sensory neurons were immunoreactive (IR) for SCN2B. These neurons had various cell body sizes. In facial skins and oral mucosae, corpuscular nerve endings contained SCN2B-immunoreactivity. SCN2B-IR nerve fibers formed nerve plexuses beneath taste buds in the tongue and incisive papilla. However, SCN2B-IR free nerve endings were rare in cutaneous and mucosal epithelia. Tooth pulps, muscle spindles and major salivary glands were also innervated by SCN2B-IR nerve fibers. A double immunofluorescence method revealed that about 40 % of SCN2B-IR neurons exhibited calcitonin gene-related peptide (CGRP)-immunoreactivity. However, distributions of SCN2B- and CGRP-IR nerve fibers were mostly different in facial, oral and cranial structures. By retrograde tracing method, 60.4 and 85.3 % of TG neurons innervating the facial skin and tooth pulp, respectively, showed SCN2B-immunoreactivity. CGRP-immunoreactivity was co-localized by about 40 % of SCN2B-IR cutaneous and tooth pulp TG neurons. In trigeminal sensory nuclei of the brainstem, SCN2B-IR neuronal cell bodies were common in deep laminae of the subnucleus caudalis, and the subnuclei interpolaris and oralis. In the mesencephalic trigeminal tract nucleus, primary sensory neurons also exhibited SCN2B-immunoreactivity. In other regions of trigeminal sensory nuclei, SCN2B-IR cells were very infrequent. SCN2B-IR neuropil was detected in deep laminae of the subnucleus caudalis as well as in the subnuclei interpolaris, oralis and principalis. These findings suggest that SCN2B is expressed by various types of sensory neurons in the TG. There appears to be SCN2B-containing pathway in the TG and trigeminal sensory nuclei.     

家族性三叉神经痛

三叉神经痛是一种临床常见疾病,典型的三叉神经痛主要表现为阵发性、闪电样的疼痛发作,疼痛剧烈,常无法忍受,呈电灼、针刺、撕裂样,每次发作持续时间数秒至数分钟不等。疼痛多发生于单侧,常有扳机点表现,其多表现为散发,而家族性三叉神经痛报道罕见,至今世界范围内报道仅50余个家系,其临床表现及发病特点与散发性三叉神经痛存在明显差别,尽管散发三叉神经痛患者的病因为责任血管压迫三叉神经REZ区已被普遍接受,但关于家族性三叉神经痛的病因是否为血管压迫存在争议,其遗传模式也没有达成一致的意见,文章复习了相关文献,并通过对这些文献进行分析综合,结合我们治疗三叉神经痛的经验,对其病因、发病机制、诊断和治疗原则、遗传模式等作了系统综述。     

CT引导下立体定向射频热凝三叉神经半月节对原发性三叉神经痛的疗效分析

目的：分析CT引导下立体定向射频热凝三叉神经半月节对原发性三叉神经痛的疗效,探讨其临床适用性。方法：选择从2011年5月至2012年12月于我院住院治疗原发性三叉神经痛的58例患者,在三维CT引导下采用通过BrainLAB手术计划系统经前入路卵圆孔穿刺三叉神经半月神经节,术中根据疼痛分布范围射频热凝三叉神经半月节。观察并比较治疗前后的VAS评分,临床疗效,术中和术后不良反应情况。结果：58例患者的穿刺手术均成功,术后1d、3d、6d的VAS评分均较治疗前显著降低（P〈0．01）;1周后58例患者中,有53例患者疼痛完全消失,l例患者偶然出现疼痛,但无需服用药物处理,共显效54例;4例患者疼痛有所减轻或疼痛发作频率降低,但仍需服用药物,或服用药物剂量较治疗前明显减少;疼痛无改善或者非用药不能缓解的持续痛仅1例。总有效例数为57例,总有效率达98．26％。术中发生不良反应6例,在术后均有所缓解。术后发生各种并发症共15例,均未明显影响手术效果。结论：CT引导可以较为准确的进入穿刺部位,使立体定向射频热凝三叉神经半月节手术更加顺利,达到治疗原发性三叉神经痛的理想效果,适合临床长期推广应用。     

改良微血管减压术治疗复发性三叉神经痛的疗效及安全性分析

目的:探讨改良微血管减压术(MVD)治疗复发性三叉神经痛的疗效及安全性。方法:回顾性分析2010年至2015年收治的50例复发性三叉神经痛患者,2012年前采取常规MVD手术方法(MVD组,n=22),2012年后采取改良MVD的手术方法(改良MVD组,n=28)。MVD组采用传统MVD对三叉神经根进行全程减压,即沿首次切口入路,依次切开皮下、肌筋膜,充分分离骨窗边缘的瘢痕组织,适当扩大骨窗直至硬脑膜充分暴露。切开硬膜,锐性分离蛛网膜后探查Meckel腔至神经出脑区(REZ),仔细探查三叉神经全段,分离压迫神经的责任血管以及首次手术置入的Teflon垫棉,对三叉神经进行全程减压。改良MVD组在此基础上,探查三叉神经颅内段及其周围结构,解剖三叉神经脑干延伸段,垫开小脑上动脉对三叉神经脑干延伸段的压迫。比较两组术后缓解率、并发症、复发情况。结果:改良MVD组术后缓解率为100.0%,显著高于MVD组72.7%(P0.05);两组术后并发症的发生率比较差异无统计学意义(P0.05);改良MVD组术后1年复发率为0%,显著低于MVD组22.7%(P0.05)。结论:MVD术中三叉神经根全程减压联合脑干延伸段减压治疗复发性三叉神经痛患者可有效缓解疼痛,降低术后复发风险,且不增加术后并发症。     

Trigeminal foraminal pattern in the face

The integration of the trigeminal nerve into the craniofacial skeleton was studied by examining cephalometrically the relationships of the openings of the branches of the trigeminal nerve to each other and to other structures. Lateral cephalograms were taken from 30 adult skulls; several linear and angular dimensions were measured from the cephalograms. The results suggest a relationship between nerve growth and bone growth in the craniofacial skeleton.     

原发性三叉神经痛和疱疹后三叉神经痛临床特征及射频热凝术后效果分析

摘要 目的：探讨原发性三叉神经痛（PTN）和疱疹后三叉神经痛（PHN）的临床特征,并比较经卵圆孔射频热凝术（RF-TC）治疗PTN和PHN的临床疗效。方法：随机选取2019年1月至2020年8月在我院治疗的三叉神经痛患者123例,其中原发性三叉神经痛90例,带状疱疹后神经痛33例。所有患者均通过RF-TC进行治疗,治疗后通过视觉模拟量表（VAS）、巴罗神经研究所疼痛强度量表对面部疼痛评分进行疼痛评估,通过巴罗神经研究所麻木评分进行麻木评定,通过健康问卷-9对患者抑郁情况进行评估,通过匹斯堡睡眠质量指数测量患者心理状态。结果：PTN患者发病年龄显著低于PHN患者（P<0.05）,而病程显著高于PHN患者（P<0.05）;PHN患者的眼支发生率高于PTN患者（39.39% vs 8.89%, P<0.05）。两组患者经RF-TC治疗前后VAS评分无显著差异（P>0.05）。PHN组从轻度到重度影响睡眠质量的比例显著高于PTN组（30.30% vs 10.00%, P<0.05）。PTN组患者治疗后中重度抑郁患者比例显著高于PHN组患者（21.11% vs 9.09%, P<0.05）。两组患者经RF-TC治疗后,临床治疗有效率、面麻木程度以及巴罗神经研究所疼痛强度量表评定的面部疼痛无显著差异（P>0.05）。结论：经卵圆孔射频热凝术治疗原发性三叉神经痛和带状疱疹后三叉神经痛是安全有效的,但治疗后疱疹后三叉神经痛失眠的发生率较高,而原发性三叉神经痛的抑郁发生率较高。     

Trigeminal chemoreception in the nasal and oral cavities

Nasal and oral trigeminal chemoreception are discussed witha focus on their functions, responses, and interactions witholfaction and gustation. Trigeminal stimulation elicits a numberof physiological reflexes which are shown to have several possibleeffects on the olfactory and gustatory systems. Based on psychophysicaland electrophysiological data, it is argued that trigeminalchemoreceptors may be stimulated by a wider range of compoundsand concentrations than is generally believed. The molecularstructures which tend to characterize effective trigeminal stimuliare also discussed. It is suggested that the evidence for thediscriminatory ability of trigeminal chemoreceptors is inconclusiveand that this remains a fundamental unanswered question. Finally,the interesting phenomenon of human preference for some initiallyaversive trigeminal stimuli is reviewed. ¹ Present address: Monell Chemical Senses Center, 3500 MarketStreet, Philadelphia, PA 19104. USA.     

Chemosensory Information Processing between Keratinocytes and Trigeminal Neurons

Trigeminal fibers terminate within the facial mucosa and skin and transmit tactile, proprioceptive, chemical, and nociceptive sensations. Trigeminal sensations can arise from the direct stimulation of intraepithelial free nerve endings or indirectly through information transmission from adjacent cells at the peripheral innervation area. For mechanical and thermal cues, communication processes between skin cells and somatosensory neurons have already been suggested. High concentrations of most odors typically provoke trigeminal sensations in vivo but surprisingly fail to activate trigeminal neuron monocultures. This fact favors the hypothesis that epithelial cells may participate in chemodetection and subsequently transmit signals to neighboring trigeminal fibers. Keratinocytes, the major cell type of the epidermis, express various receptors that enable reactions to multiple environmental stimuli. Here, using a co-culture approach, we show for the first time that exposure to the odorant chemicals induces a chemical communication between human HaCaT keratinocytes and mouse trigeminal neurons. Moreover, a supernatant analysis of stimulated keratinocytes and subsequent blocking experiments with pyrodoxalphosphate-6-azophenyl-2′,4′-disulfonate revealed that ATP serves as the mediating transmitter molecule released from skin cells after odor stimulation. We show that the ATP release resulting from Javanol® stimulation of keratinocytes was mediated by pannexins. Consequently, keratinocytes act as chemosensors linking the environment and the trigeminal system via ATP signaling.     

Sensorimotor and Pain Modulation Brain Abnormalities in Trigeminal Neuralgia: A Paroxysmal,Sensory-Triggered Neuropathic Pain

Objective

Idiopathic trigeminal neuralgia (TN) is characterized by paroxysms of severe facial pain but without the major sensory loss that commonly accompanies neuropathic pain. Since neurovascular compression of the trigeminal nerve root entry zone does not fully explain the pathogenesis of TN, we determined whether there were brain gray matter abnormalities in a cohort of idiopathic TN patients. We used structural MRI to test the hypothesis that TN is associated with altered gray matter (GM) in brain areas involved in the sensory and affective aspects of pain, pain modulation, and motor function. We further determined the contribution of long-term TN on GM plasticity.

Methods

Cortical thickness and subcortical GM volume were measured from high-resolution 3T T1-weighted MRI scans in 24 patients with right-sided TN and 24 healthy control participants.

Results

TN patients had increased GM volume in the sensory thalamus, amygdala, periaqueductal gray, and basal ganglia (putamen, caudate, nucleus accumbens) compared to healthy controls. The patients also had greater cortical thickness in the contralateral primary somatosensory cortex and frontal pole compared to controls. In contrast, patients had thinner cortex in the pregenual anterior cingulate cortex, the insula and the orbitofrontal cortex. No relationship was observed between GM abnormalities and TN pain duration.

Conclusions

TN is associated with GM abnormalities in areas involved in pain perception, pain modulation and motor function. These findings may reflect increased nociceptive input to the brain, an impaired descending modulation system that does not adequately inhibit pain, and increased motor output to control facial movements to limit pain attacks.     

Trigeminal ganglion cells cocultured with gut express vasoactive intestinal peptide

The plasticity of neural crest cells for the expression of adrenergic and cholinergic transmitter phenotypes has been well studied. The object of this study was to determine if cells of a sensory ganglion are capable of neuropeptide transmitter plasticity. We studied whether cells of the trigeminal ganglion, which do not express the neuropeptide vasoactive intestinal peptide (VIP) in vivo, would express this peptide when grown with a tissue the gut, that contains large numbers of VIP neurons. Embryonic aneural chick rectum was explanted with the embryonic quail trigeminal ganglion on the chorioallantoic membrane of chick hosts for 7-8 days. The explants were fixed, sectioned, and stained for VIP immunoreactivity (IR), for neurofilament protein immunoreactivity, and for the quail nucleolar marker. In sections of the explants we observed two populations of quail neurons: small (10-13 microns) VIP-IR cells and large (25-32 microns) cells lacking VIP-IR and resembling native trigeminal neurons. Trigeminal ganglia explanted with embryonic heart or trigeminal ganglia explanted alone lacked small VIP-IR cells but contained large VIP-negative neurons. These results show that cells of the trigeminal ganglion grown with the gut can express a neuropeptide they do not express in the absence of the gut or in vivo. Thus the embryonic trigeminal ganglion contains cells that are plastic with respect to neuropeptide expression.     

Microsurgical Vascular Decompression for Trigeminal Neuralgia and Hemifacial Spasm

Vascular cross-compression of cranial nerves has been proposed as the cause of cranial neuropathies, including trigeminal neuralgia and hemifacial spasm. Over the last decade we have used microsurgical vascular decompression to treat these two disorders. Results in 50 patients treated for trigeminal neuralgia have been excellent in 42, good in 5 and poor in 2; and 1 patient was cured after a second operation. Results in 22 patients treated for hemifacial spasm have been excellent in 18, good in 2 and fair in 1. One patient died. There were no late recurrences of symptoms.The pathophysiological mechanisms of trigeminal neuralgia and hemifacial spasm remain unknown.     

Choline Acetyltransferase Activity in the Rat Trigeminal System

Choline acetyltransferase activity was investigated in the superior cervical ganglia and in six microdissected regions of the medulla oblongata of the rat ipsilateral and contralateral to electrolytic lesions of the trigeminal sensory ganglia (Gasserian). Electrolytic lesions of the Gasserian ganglia failed to modify levels of enzymatic activity in all structures studied. This result would be an argument against the existence of a major cholinergic population of sensory neurones in the trigeminal system.     

Intracranial recording from the brain-stem and the trigeminal nerve following upper lip stimulation

Short latency evoked potentials following stimulation of the upper lip were recorded intracranially during neurosurgical procedures in 14 patients. In 10 patients, a suboccipital craniectomy provided direct access to the trigeminal root and the pons at the root entry zone. Direct recordings from the trigeminal root were characterized by a large triphasic potential at 2.4–2.7 msec. The latency of this potential increased as a result of moving the recording electrode proximally towards the brain-stem. The same potential could be recorded from the brain-stem surface at a latency suggesting an intra-axial presynaptic origin. A second component, N4.7, was recorded from over the most rostral aspect of the brain-stem in 3 patients and from the tentorium free edge in 4 patients. This potential of smaller amplitude did not show significant difference in latency or polarity at various electrode locations, suggesting a deep diencephalic origin remote from the recording electrode.