Different Pain States of Trigeminal Neuralgia Make Significant Changes in the Plasma Proteome and Some Biochemical Parameters: a Preliminary Cohort Study

The Superior Cerebellar Artery: Variability and Clinical Significance

The superior cerebellar artery (SCA) arises from the distal part of the basilar artery and passes by the oculomotor, trochlear, and trigeminal nerves. SCA is known to play a crucial role in the development of trigeminal neuralgia. However, due to its anatomical variability, it may also trigger other neurovascular compression (NVC), including hemifacial spasm, oculomotor nerve palsy, and ocular neuromyotonia. Additionally, it may be associated with ischemic syndromes and aneurysm development, highlighting its clinical significance. The most common anatomical variations of the SCA include duplication, a single vessel origin from the posterior cerebral artery (PCA), and a common trunk with PCA. Rarely observed variants include bifurcation and origin from the internal carotid artery. Certain anatomical variants such as early bifurcation and caudal course of duplicated SCA trunk may increase the risk of NVC. In this narrative review, we aimed to examine the impact of the anatomical variations of SCA on the NVCs based on papers published in Pubmed, Scopus, and Web of Science databases with a snowballing approach. Our review emphasizes the importance of a thorough understanding of the anatomical variability of SCA to optimize the management of patients with NVCs associated with this artery.

[Dolichoectasia of the basilar artery caused by cystic medial degeneration, as a cause of neurovascular conflict with damage to the trigeminal, facial and vestibulocochlear nerves]

Cystic medial degeneration (Gsell-Erdheim syndrome, cystic medial necrosis) is considered to be a nonspecific histological manifestation of a group of diseases characterized by degenerative changes in the media, affecting primarily the aorta and adjacent branches, which leads to destruction of the vessel wall, followed by its expansion and, possibly, rupture. The authors describe a case of a 65-year-old female patient with a neurovascular conflict of the three cranial nerves with dolichoectatic basilar artery due to cystic medial degeneration. As a result, the patient has clinical manifestations in the form of hemifacial spasm, trigeminal neuralgia and vestibular paroxysmia. Data from instrumental studies and treatment provided are presented. Neurovascular conflict can be identified in various diseases and is characterized by the complex etiology. The most common clinical manifestations of neurovascular conflict are trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia, and vestibular paroxysmia.

Artificial Neural Networks Coupled with MALDI-TOF MS Serum Fingerprinting To Classify and Diagnose Pathological Pain Subtypes in Preclinical Models

Pathological pain subtypes can be classified as either neuropathic pain, caused by a somatosensory nervous system lesion or disease, or nociplastic pain, which develops without evidence of somatosensory system damage. Since there is no gold standard for the diagnosis of pathological pain subtypes, the proper classification of individual patients is currently an unmet challenge for clinicians. While the determination of specific biomarkers for each condition by current biochemical techniques is a complex task, the use of multimolecular techniques, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), combined with artificial intelligence allows specific fingerprints for pathological pain-subtypes to be obtained, which may be useful for diagnosis. We analyzed whether the information provided by the mass spectra of serum samples of four experimental models of neuropathic and nociplastic pain combined with their functional pain outcomes could enable pathological pain subtype classification by artificial neural networks. As a result, a simple and innovative clinical decision support method has been developed that combines MALDI-TOF MS serum spectra and pain evaluation with its subsequent data analysis by artificial neural networks and allows the identification and classification of pathological pain subtypes in experimental models with a high level of specificity.

Proteomics analysis revealed the presence of inflammatory and oxidative stress markers in the plasma of migraine patients during the pain period

BACKGROUND

There is increasing evidence that some biomarkers are implicated in migraine pathogenesis. This study looks at plasma proteome in migraine patients for potential protein biomarkers.

METHODS

This case-control study has two phases. In phase I, plasma samples were collected from three groups, including twenty-three episodic migraineurs, thirty-five chronic migraineurs, and twenty-nine healthy subjects. In phase II, plasma samples were prepared from two groups, including five episodic and five chronic migraine cases, during the pain and 24 h after the pain-free periods. Two-dimensional gel electrophoresis (2-DE) was performed on plasma proteins. The possible corresponding proteins for the differentially expressed spots between groups investigated by the Melanie software were predicted by 2-DE gels of the EXPASY database. LC-MS/MS additionally analyzed phase II data.

RESULTS

Expression levels of haptoglobin, clusterin, fibrinogen alpha chain, fibrinogen beta chain, complement c3, transthyretin, α1-microglobulin, and retinol-binding protein 4 were shown considerable changes in migraine patients compared to controls or their pain-free period.

CONCLUSION

Differences in expression levels for several proteins were observed across groups. Most of these are associated with inflammation, oxidative stress, and neuroprotection, which can be considered potential disease biomarkers. However, further research is necessary for this respect.

The Underlying Pathogenesis of Neurovascular Compression Syndromes: A Systematic Review

Neurovascular compression syndromes (NVC) are challenging disorders resulting from the compression of cranial nerves at the root entry/exit zone. Clinically, we can distinguish the following NVC conditions: trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia. Also, rare cases of geniculate neuralgia and superior laryngeal neuralgia are reported. Other syndromes, e.g., disabling positional vertigo, arterial hypertension in the course of NVC at the CN IX-X REZ and torticollis, have insufficient clinical evidence for microvascular decompression. The exact pathomechanism leading to characteristic NVC-related symptoms remains unclear. Proposed etiologies have limited explanatory scope. Therefore, we have examined the underlying pathomechanisms stated in the medical literature. To achieve our goal, we systematically reviewed original English language papers available in Pubmed and Web of Science databases before 2 October 2021. We obtained 1694 papers after eliminating duplicates. Only 357 original papers potentially pertaining to the pathogenesis of NVC were enrolled in full-text assessment for eligibility. Of these, 63 were included in the final analysis. The systematic review suggests that the anatomical and/or hemodynamical changes described are insufficient to account for NVC-related symptoms by themselves. They must coexist with additional changes such as factors associated with the affected nerve (e.g., demyelination, REZ modeling, vasculature pathology), nucleus hyperexcitability, white and/or gray matter changes in the brain, or disturbances in ion channels. Moreover, the effects of inflammatory background, altered proteome, and biochemical parameters on symptomatic NVC cannot be ignored. Further studies are needed to gain better insight into NVC pathophysiology.

Interplay of Oral, Mandibular, and Facial Disorders and Migraine

PURPOSE OF THE REVIEW

Migraine and other primary headache disorders can be localized in the face resembling facial or dental pain, indicating the influence of the trigeminovascular system in the structures innervated by the maxillary (V2) and mandibulary (V3) branches of the trigeminal nerve. Disorders of oral and craniofacial structures may influence primary headache disorders. In the current article, we review the potential links of this interplay.

RECENT FINDINGS

This interplay may be related to anatomy, with the trigeminal pathway and the involvement of both peripheral and central mechanisms, and the presence of calcitonin gene-related peptide (CGRP), a key mediator in migraine pathophysiology. CGRP is also involved in the pathophysiology of temporomandibular disorders (TMD) and their comorbidity with migraine and is also implicated in dental and periodontal pathology. Inflammatory and pathological processes of these structures and their trigeminal nociceptive pathways may influence the trigeminovascular system and consequently may exacerbate or even potentially trigger migraine.

Investigation of cattle plasma proteome in response to pain and inflammation using next generation proteomics technique, SWATH-MS

Pain assessment in farm animals has primarily relied on a combination of behavioral and physiological responses, although these are relatively subjective and difficult to quantify. It is essential to develop more effective biomarkers of pain in production animals since they are frequently exposed to routine surgical husbandry procedures. More effective biomarkers of pain would improve welfare, limit the loss of productivity associated with pain and permit better assessment of analgesics. This study aimed to investigate the use of a modern mass spectrometry data independent acquisition strategy, termed Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS), to detect candidate protein biomarkers that are known to associate with nociceptive and inflammatory processes in cattle, which could then be used to assess the efficacy of potential analgesics. Calves were randomly divided into two groups that were either surgically dehorned or subjected to restraint stress, without provision of anaesthesia or analgesia in accordance with current industry standards. Samples were analysed before and after dehorning at multiple timepoints. Significant changes in protein concentrations were detected predominantly at 24 and 96 h following dehorning, including kininogens, proteins associated with the coagulation and complement cascades and serine protease inhibitors. Gene ontology analysis revealed that the identified candidate biomarkers were associated with stress, wound healing, immune response, blood coagulation and the inflammatory and acute phase responses, which could be expected following surgical damage to tissues, but can now be more objectively assessed. These results offer more definitive and quantitative monitoring of response to tissue injury induced pain and inflammation.

Efficacy of Erenumab in the Treatment of Trigeminal Neuralgia: A Retrospective Case Series

Objective

Trigeminal neuralgia (TN) is a chronic, often refractory, pain condition, which adversely affects the lives of patients. Current treatments are only mildly effective. Anti-calcitonin gene-related peptide (CGRP) monoclonal antibodies have been successfully studied in the treatment of migraines. CGRP plays a role in both TN and migraine. It is prudent to attempt CGRP monoclonal antibody therapy in TN. Erenumab, a human anti-CGRP monoclonal antibody medication, modulates CGRP, which is elevated in patients with TN. The primary objective of this study was to evaluate the efficacy of erenumab for patients with TN.

Methods

Retrospective analysis was performed on data collected from 10 patients diagnosed with TN and treated with erenumab for 6 months. Pain was tracked using a numeric pain rating scale (NPRS) from 0 to 10. The effect of erenumab on NPRS after 6 months' time was the primary end point. Secondary end points included side effects to therapy, improvement in headache frequency in those with comorbid migraine, evaluating mood following therapy, and global mood improvement using scale (worse, no change, improved).

Results

Nine of 10 patients (90.0%) reported improvement in pain severity and in global mood improvement. Three patients reported resolution of anxiety and/or depression. Side effects were minimal, with 3 patients reporting constipation, injection site reactions, or both.

Conclusions

Based on these results, erenumab appears to be an efficacious treatment option for patients with refractory TN. Patients experienced improvement in pain, reduced frequency of headache, and improvement in mood. Treatment was well tolerated with only mild side effects reported.

Classification of Evidence

This study provides Class IV evidence that erenumab increases the probability of improved pain control in patients with medication-resistant TN.

Exploring the roles of neuropeptides in trigeminal neuropathic pain: A systematic review and narrative synthesis of animal studies

OBJECTIVE

This systematic review aims to explore the changes in expression of neuropeptides and/or their receptors following experimental trigeminal neuropathic pain in animals.

DESIGN

MEDLINE, Embase, and Scopus were searched for publications up to 31st March 2021. Study selection and data extraction were completed by two independent reviewers based on the eligibility criteria. The quality of articles was judged based on the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk-of-bias tool.

RESULTS

A total of 19 studies satisfied the eligibility criteria and were included for narrative synthesis. Methods of trigeminal neuropathic pain induction were nerve ligation, nerve compression/crush, nerve transection and dental pulp injury. Animal behaviours used for pain verification were evoked responses to mechanical and thermal stimuli. Non-evoked behaviours, including vertical exploration, grooming and food consumption, were also employed in some studies. Calcitonin gene-related peptide (CGRP) and substance P were the most frequently reported neuropeptides. Overall, unclear to high risk of bias was identified in the included studies.

CONCLUSIONS

Limited evidence has suggested the pro-nociceptive role of CGRP in trigeminal neuropathic pain. In order to further translational pain research, animal models of trigeminal neuropathic pain and pain validation methods need to be optimised. Complete reporting of future studies based on available guidelines to improve confidence in research is encouraged.

Trigeminal neuralgia: An overview from pathophysiology to pharmacological treatments

The trigeminal nerve (V) is the fifth and largest of all cranial nerves, and it is responsible for detecting sensory stimuli that arise from the craniofacial area. The nerve is divided into three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3); their cell bodies are located in the trigeminal ganglia and they make connections with second-order neurons in the trigeminal brainstem sensory nuclear complex. Ascending projections via the trigeminothalamic tract transmit information to the thalamus and other brain regions responsible for interpreting sensory information. One of the most common forms of craniofacial pain is trigeminal neuralgia. Trigeminal neuralgia is characterized by sudden, brief, and excruciating facial pain attacks in one or more of the V branches, leading to a severe reduction in the quality of life of affected patients. Trigeminal neuralgia etiology can be classified into idiopathic, classic, and secondary. Classic trigeminal neuralgia is associated with neurovascular compression in the trigeminal root entry zone, which can lead to demyelination and a dysregulation of voltage-gated sodium channel expression in the membrane. These alterations may be responsible for pain attacks in trigeminal neuralgia patients. The antiepileptic drugs carbamazepine and oxcarbazepine are the first-line pharmacological treatment for trigeminal neuralgia. Their mechanism of action is a modulation of voltage-gated sodium channels, leading to a decrease in neuronal activity. Although carbamazepine and oxcarbazepine are the first-line treatment, other drugs may be useful for pain control in trigeminal neuralgia. Among them, the anticonvulsants gabapentin, pregabalin, lamotrigine and phenytoin, baclofen, and botulinum toxin type A can be coadministered with carbamazepine or oxcarbazepine for a synergistic approach. New pharmacological alternatives are being explored such as the active metabolite of oxcarbazepine, eslicarbazepine, and the new Nav1.7 blocker vixotrigine. The pharmacological profiles of these drugs are addressed in this review.

Identification of candidate proteomic markers in the serum of medication overuse headache patients: An exploratory study

PURPOSE OF THE STUDY

The pathophysiological mechanism of medication overuse headache is uncertain; no distinctive markers have been described right now. The aim of this study was to conduct proteomic analyses on serum samples from patients with medication overuse headache and healthy individuals. Specifically, mono- (SDS-PAGE) and two-dimensional gel electrophoresis (2-DE) followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) were used to evaluate changes in serum proteins.

MAIN FINDINGS

By SDS-PAGE, four over-expressed bands were revealed in patients, compared to controls. 2-DE combined with LC-MS/MS analysis allowed confirmation of some proteins preliminarily detected by SDS-PAGE: Hemopexin, alpha-1-acid glycoprotein 1, apolipoprotein A4 and haptoglobin. Moreover, other differential proteins were isolated, mostly increased in MOH patients: Alpha-1-antitrypsin, immunoglobulin heavy constant alpha 1, retinol binding protein and transthyretin. Only one protein, immunoglobulin kappa constant, was decreased in the patients' group.

CONCLUSIONS

The investigation of the serum proteome can offer a better understanding about biological mechanisms underlying medication overuse headache. Specifically, medication overuse headache shares some serum biochemical markers with chronic pain conditions. Further studies might uncover the relevance of these proteins in medication overuse headache.

Biomarkers in Temporomandibular Disorder and Trigeminal Neuralgia: A Conceptual Framework for Understanding Chronic Pain

In this review, we will explore the use of biomarkers in chronic pain, using the examples of two prototypical facial pain conditions: trigeminal neuralgia and temporomandibular disorder. We will discuss the main categories of biomarkers and identify various genetic/genomic, molecular, neuroradiological, and psychophysical biomarkers in both facial pain conditions, using them to compare and contrast features of neuropathic, nonneuropathic, and mixed pain. By using two distinct model facial pain conditions to explore pain biomarkers, we aim to familiarize readers with different types of biomarkers currently being studied in chronic pain and explore how these biomarkers may be used to develop new precision medicine approaches to pain diagnosis, prognosis, and management.

The Role of Vitamin D in Primary Headache-from Potential Mechanism to Treatment

Some studies have suggested a link between vitamin D and headache; however, the underlying physiological mechanisms are unclear. We aimed to summarize the available evidence on the relationship between vitamin D and the various subtypes of primary headaches, including migraines and tension-type headaches. All articles concerning the association between primary headache and vitamin D published up to October 2019 were retrieved by searching clinical databases, including: EMBASE, MEDLINE, PubMed, Google scholar, and the Cochrane library. All types of studies (i.e., observational, cross-sectional, case-control, and clinical trials) were included. We identified 22 studies investigating serum vitamin D levels in association with headaches. Eight studies also evaluated the effect of vitamin D supplementation on the various headache parameters. Among them, 18 studies showed a link between serum vitamin D levels and headaches, with the strongest connection reported between serum vitamin D levels and migraine. Overall, there is not enough evidence to recommend vitamin D supplementation to all headache patients, but the current literature indicates that it may be beneficial in some patients suffering headaches, mainly migraineurs, to reduce the frequency of headaches, especially in those with vitamin D deficiency.