Sex differences in trigeminal neuralgia: a focus on radiological and clinical characteristics

BTX-A inhibited trigeminal neuralgia by blocking the NLRP3 pathway in rats

Few studies have examined the mechanisms underlying the development of trigeminal neuralgia involving the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3). The purpose of this experiment was to investigate the role of NLRP3 in the antinociceptive effects of botulinum toxin type A (BTX-A) in trigeminal neuralgia. We used a trigeminal neuralgia animal model induced by injecting 1-acyl-2-lyso-sn-glycero-3-phosphate (LPA) into the trigeminal nerve root of rats. Rats treated with LPA showed a significant increase in the expression of NLRP3 in the trigeminal ganglion 9 days after LPA injection. Furthermore, the levels of interleukin (IL)-1β, IL-18, and tumor necrosis factor (TNF)-α increased on postoperative day 9. Subcutaneous administration of BTX-A (3 U/kg) in the vibrissa pad resulted in a significant attenuation of mechanical allodynia, and the antiallodynic effects lasted for 7 days. The upregulated NLRP3 expression in the trigeminal ganglion was suppressed 2 days after the injection of BTX-A. Moreover, the BTX-A injection significantly reduced the concentrations of IL-1β, IL-18, and TNF-α in the trigeminal ganglion. Intraganglionic injection of an NLRP3 inhibitor blocked mechanical allodynia and attenuated the upregulated cytokine concentrations in the LPA-treated rats. These results indicate that BTX-A induces its antinociceptive effects in the LPA-induced trigeminal neuralgia animal model by attenuating the NLRP3-cytokine pathway in the trigeminal ganglion.

Structural brain alterations and changes in resting-state functional connectivity in patients with trigeminal neuralgia: A meta-analysis

BACKGROUND

Trigeminal neuralgia (TN) is a chronic pain condition characterized by severe, electric shock-like pain in one or more branches of the trigeminal nerve. Even though neuroimaging studies have highlighted alterations in brain cortical and subcortical structure and functional connectivity, findings are heterogeneous.

OBJECTIVE

This meta-analysis aims to synthesize structural and functional brain changes in TN patients through a coordinate-based meta-analysis using GingerALE.

METHODS

A search on PubMed, Google Scholar, and Scopus was conducted to select pertinent publications on structural magnetic resonance imaging (MRI) (brain volume and cortical thickness) and resting-state functional MRI in TN patients that were published before January 2024. Activation likelihood estimation (ALE) was used to identify consistent brain alteration patterns across studies.

RESULTS

A total of 1436 papers were identified and, after review based on the predefined inclusion and exclusion criteria, 13 papers (538 patients) discussing structural brain changes and 11 studies (368 patients) discussing resting-state functional connectivity studies were selected for inclusion. Structural and functional alterations in TN were observed in the left thalamus.

CONCLUSIONS

This meta-analysis provides a comprehensive examination of structural and functional abnormalities in TN patients, highlighting consistent alterations in left thalamus. Future research should identify brain structural and functional changes specific for TN as compared to other forms of chronic pain, explore longitudinal changes correlated to clinical parameters, and perform intra-population studies to address lateralization, to enhance diagnostic and therapeutic outcomes for TN patients.

Pathogenesis, Diagnosis, and Management of Trigeminal Neuralgia: A Narrative Review

Trigeminal neuralgia (TN) is an excruciating neurological disorder characterized by intense, stimulus-induced, and transient facial stabbing pain. The classification of TN has changed as a result of new discoveries in the last decade regarding its symptomatology, pathogenesis, and management. Because different types of facial pain have different clinical therapy and neuroimaging interpretations, a precise diagnosis is essential. Diagnosis should include magnetic resonance imaging with specific sequences to rule out secondary causes and to identify possible neurovascular contact. The purpose of demonstrating a neurovascular contact is to aid in surgical decision making, not to validate a diagnosis. Microvascular decompression is the first-line procedure for individuals who do not respond to medical management, whereas carbamazepine and oxcarbazepine are the preferred medications for long-term care. New developments in animal models and neuroimaging methods will shed more light on the biology and etiology of TN. This paper reviews the pathogenesis, the clinical features, the diagnosis, and the management of TN. Furthermore, the potential role of low-intensity pulsed ultrasound in neurological disorders is discussed.

The Impact of Microvascular Decompression on Pain Management in Trigeminal Neuralgia: Clinical Insights

Background and aim Trigeminal neuralgia (TN) is a chronic disorder accompanied by recurrent severe pain affecting the face. Many medical regimens are used in the treatment of trigeminal neuralgia. Neurosurgery intervention is the best treatment option, especially with the failure of medical therapy. The aim of the study was to assess the efficacy and outcomes of microvascular decompression for the management of trigeminal neuralgia in Erbil hospitals. Methods This is a prospective clinical study done to treat patients with classical or idiopathic (only patients with neurovascular compression) trigeminal neuralgia by microvascular decompression surgery. It was carried out in Hawler Hospital for cardiac and special surgery and Par Hospital in Erbil city, Kurdistan region, Iraq, from April 2023 to February 2024 on a sample of 21 patients who were diagnosed with trigeminal neuralgia. Results The preoperative mean pain severity score of patients with TN was 8.9±1.2. The means of pain severity score at early postoperative, two weeks postoperative, two months postoperative, six months postoperative, and twelve months postoperative were 2.5, 1.8, 1.3, 0.7, and 0.4, respectively. The preoperative pain severity score of patients with TN was significantly higher and showed a significant decrease postoperatively. The mean pain severity score of patients with TN was significantly reduced twelve months postoperatively. Postoperative complications were present in 14 (66.7%) patients with TN, commonly paresthesia in nine (42.9%), and hearing symptoms in five (23.8%) patients. Conclusion The microvascular decompression is an effective and safe surgical treatment of trigeminal neuralgia.

Altered structure and functional connection of subcortical gray matter in female patients with classical trigeminal neuralgia

The etiology of classical trigeminal neuralgia (CTN) is still unclear. A better understanding of the cerebral structural and functional changes in female patients with CTN may provide important novel insights into the pathophysiologic mechanisms of female CTN. A total 37 female CTN patients were included and referred to MRI scans, comprising with 19 left CTN and 18 right CTN patients. We analyzed the volume and shape of subcortical gray matter (GM), and the functional connectivity (FC) between the accumbens nucleus (NAc) and whole brain in right and left CTN patients respectively. We found left CTN patients had a reduced right NAc volume compared to controls, similarly, the right CTN had the decreased volume in the left NAc. Vertex-wise shapes of right NAc in left CTN patients showed significant regional shape deformation on the anterior, medial and ventroposterior aspects, in contrast, left NAc of right CTN patients showed significant regional shape deformation on the anterior and posterior aspect. Furthermore, patients with left CTN showed significantly lower FC between the right NAc and right orbitofrontal cortex than control subjects. The volume of NAc in all CTN was significantly related to the perception of present pain intensity. The CTN might be majorly caused by volume reduction in NAc. A greater understanding of the neurobiological basis of pain-related changes in NAc will provide the knowledge for the development of novel NAc based therapeutic targets for pain management or even prevention in CTN patients.

Enkephalins and Pain Modulation: Mechanisms of Action and Therapeutic Perspectives

Enkephalins, a subclass of endogenous opioid peptides, play a pivotal role in pain modulation. Enkephalins primarily exert their effects through opioid receptors located widely throughout both the central and peripheral nervous systems. This review will explore the mechanisms by which enkephalins produce analgesia, emotional regulation, neuroprotection, and other physiological effects. Furthermore, this review will analyze the involvement of enkephalins in the modulation of different pathologies characterized by severe pain. Understanding the complex role of enkephalins in pain processing provides valuable insight into potential therapeutic strategies for managing pain disorders.

Trigeminal neuralgia

Trigeminal neuralgia (TN) is a facial pain disorder characterized by intense and paroxysmal pain that profoundly affects quality of life and presents complex challenges in diagnosis and treatment. TN can be categorized as classical, secondary and idiopathic. Epidemiological studies show variable incidence rates and an increased prevalence in women and in the elderly, with familial cases suggesting genetic factors. The pathophysiology of TN is multifactorial and involves genetic predisposition, anatomical changes, and neurophysiological factors, leading to hyperexcitable neuronal states, central sensitization and widespread neural plasticity changes. Neurovascular compression of the trigeminal root, which undergoes major morphological changes, and focal demyelination of primary trigeminal afferents are key aetiological factors in TN. Structural and functional brain imaging studies in patients with TN demonstrated abnormalities in brain regions responsible for pain modulation and emotional processing of pain. Treatment of TN involves a multifaceted approach that considers patient-specific factors, including the type of TN, with initial pharmacotherapy followed by surgical options if necessary. First-line pharmacological treatments include carbamazepine and oxcarbazepine. Surgical interventions, including microvascular decompression and percutaneous neuroablative procedures, can be considered at an early stage if pharmacotherapy is not sufficient for pain control or has intolerable adverse effects or contraindications.

Systematic review on the frequency of occurrence in nerve branches and the side of the face involved in trigeminal neuralgia and its clinical implication

Purpose

The purpose of this systematic review is to answer the focused question, "What is the commonly affected nerve branch and the side of the face involved in trigeminal neuralgia?"

Types of studies reviewed

This systematic review included studies reporting commonly affected trigeminal nerve branches and the side of the face involved in trigeminal neuralgia. To find the potential studies published, the authors utilized specific search databases such as PubMed, and Google scholar.

Results

Among 132 published studies, the authors selected only 11 to be included for this systematic review. The sample size ranged from 50 to 43,518 study subjects. This review identified that the mandibular branches of the trigeminal nerve were the most affected, followed by the maxillary branch. The review also identified that the right side of the face was predominantly affected.

Conclusion and practical implications

The authors of this review identified a higher occurrence of trigeminal neuralgia in the mandibular division of the nerve, commonly affected on the right side of the face. Further prospective-based research and meta-analysis are required to validate the commonly occurring trigeminal nerve branch and sidedness of the face involved with its clinical implications in trigeminal neuralgia.

Mental Nerve Neurectomy: A Comparison of Titanium Screw Versus Gutta-Percha Oburation of the Mental Foramen

OBJECTIVE

 This study aims to compare the two mental foramen obturating techniques in parameters like operator's ease, postoperative displacement of obturation material, and remission of pain after peripheral neurectomy in patients with trigeminal neuralgia.

STUDY DESIGN

 This study adopts a single-centered comparative analytical approach.

PLACE AND DURATION OF STUDY

This study was performed in the Department of Oral and Maxillofacial Surgery, Armed Forces Institute of Dentistry (AFID), from October 1, 2023, to February 10, 2024.

METHODOLOGY

Sixty patients fulfilling the inclusion criteria were included and divided into two groups (30 each), and peripheral neurectomy was performed under local anesthesia. In one group, gutta-percha sticks were used to obturate the foramina, and in the other group, titanium screws were used. Postoperatively, the operator's ease, postoperative displacement, and relapse of pain were recorded.

RESULTS

 Titanium screws were easy to handle, and there was no relapse of pain because of no displacement postoperatively when compared with gutta-percha sticks, which were hard to manipulate and showed a relapse of pain.

CONCLUSIONS

 Titanium screws have better postoperative outcomes when compared with gutta-percha sticks in terms of the operator's ease, relapse of pain, and postoperative displacement.

The Therapeutic Effect of Botulinum Toxin Type A on Trigeminal Neuralgia: Are There Any Differences between Type 1 versus Type 2 Trigeminal Neuralgia?

BACKGROUND

Botulinum toxin type A is an effective treatment for trigeminal neuralgia. Moreover, its efficacy in type 2 trigeminal neuralgia and comparative studies between type 1 and type 2 trigeminal neuralgia (TN) still need to be improved.

METHODS

We treated 40 TN patients with onabotulinumtoxinA; 18 had type 1 TN, and 22 had type 2 TN. We compared the baseline pain score with the Visual Analogue Scale (VAS) and paroxysm frequency (number per week) at the baseline with those obtained at 1-month and 3-month follow-ups. Nonetheless, we compared the baseline Penn Facial Pain Scale with the scores obtained at the 1-month follow-up.

RESULTS

BoNT/A effectively reduced pain intensity and frequency at the 1-month and 3-month follow-ups. Moreover, the type 1 TN and type 2 TN groups had baseline pain scores of 7.8 ± 1.65 and 8.4 ± 1.1, respectively. Pain significantly improved (p < 0.001) in both groups to 3.1 ± 2.3 (type 1 TN) and 3.5 ± 2.3 (type 2 TN) at the 1-month follow-up and to 3.2 ± 2.5 (type 1 TN) and 3.6 ± 2.5 (type 2 TN) at the 3-month follow-up. There was no difference between the two groups (p 0.345). The baseline paroxysm frequencies (number per week) were 86.7 ± 69.3 and 88.9 ± 62.2 for the type 1 and type 2 TN groups, respectively; they were significantly reduced in both groups at the 1-month and 3-month follow-ups without significant differences between the two groups (p 0.902). The Pain Facial Pain Scale improved at the 1-month follow-up, and no significant differences were found between the two groups. There was a strong correlation between background pain and paroxysm pain intensity (r 0.8, p < 0.001).

CONCLUSIONS

Botulinum toxin type A effectively reduced the pain, paroxysm frequency, and PFPS scores of type 1 and type 2 trigeminal neuralgia patients without statistically significant differences. Facial asymmetry was the only adverse event.