Post-traumatic trigeminal neuropathy (PTTN) is a type of chronic pain caused by damage to the trigeminal nerve. A previous study reported that pretreatment with anti-high mobility group box-1 (HMGB1) neutralizing antibodies (nAb) prevented the onset of PTTN following distal infraorbital nerve chronic constriction injury (dIoN-CCI) in male mice. Clinical evidence indicates a high incidence of PTTN in females. Although our previous study found that perineural HMGB1 is crucial in initiation of PTTN in male mice, it is currently unknown whether HMGB1 is also involved in the pathogenesis of PTTN in female mice. Therefore, in the current study, we examined the effect of anti-HMGB1 nAb on pain-like behavior in female mice following dIoN-CCI surgery. We found that dIoN-CCI surgery enhanced reactivity to mechanical and cold stimuli in female mice, which was suppressed by treatment with anti-HMGB1 nAb. Moreover, the increase in macrophages after dIoN-CCI was significantly attenuated by pretreatment with anti-HMGB1 nAb. Furthermore, anti-HMGB1 nAb treatment inhibited microglial activation in the trigeminal spinal tract nucleus. These data suggest that HMGB1 also plays a crucial role in the onset of PTTN after nerve injury in female mice. Thus, anti-HMGB1 nAb could be a novel therapeutic agent for inhibiting the onset of PTTN in female and male mice.

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OBJECTIVE: MR neurography has the ability to detect and depict peripheral nerve injuries. This study evaluated the potential of MR neurography in the diagnosis of post-traumatic trigeminal neuropathy.
METHODS: Forty-one participants prospectively underwent MR neurography of the lingual and inferior alveolar nerves using a 3D TSE STIR black-blood sequence. Two blinded and independent observers recorded the following information for each nerve of interest: presence of injury, nerve thickness, nerve signal intensity, MR neurography Sunderland class, and signal gap. Afterwards, the apparent nerve-muscle contrast-to-noise ratio and apparent signal-to-noise ratio were calculated. Clinical data (neurosensory testing score and clinical Sunderland class) was extracted retrospectively from the medical records of patients diagnosed with post-traumatic trigeminal neuropathy.
RESULTS: Compared to neurosensory testing, MR neurography had a sensitivity of 38.2% and specificity of 93.5% detecting nerve injuries. When differentiated according to clinical Sunderland class, sensitivity was 19.1% in the presence of a low class injury (I to III) and improved to 83.3% in the presence of a high class (IV to V). Specificity remained unchanged. The area under the curve using the apparent nerve-muscle contrast-to-noise ratio, apparent signal-to-noise ratio, and nerve thickness to predict the presence of an injury was 0.78 (p < .05). Signal intensities and nerve diameter increased in injured nerves (p < .05). Clinical and MR neurography Sunderland scores positively correlated (correlation coefficient = 0.53; p = .005).
CONCLUSIONS: This study shows that MR neurography can accurately differentiate between injured and healthy nerves, especially in the presence of a more severe nerve injury.
CONCLUSIONS: MR neurography is not only able to detect trigeminal nerve injuries, but it can also provide information about the anatomical specifications of the injury, which is not possible with clinical neurosensory testing. This makes MR neurography an added value in the management of post-traumatic trigeminal neuropathy.
CONCLUSIONS: • The current diagnosis of post-traumatic trigeminal neuropathy is mainly based on clinical examination. • MR neurography is able to visualize and stratify peripheral trigeminal nerve injuries. • MR neurography contributes to the diagnostic process as well as to further decision-making.

We present the case of a 42-year-old woman with rheumatoid arthritis and Sjögren\'s syndrome treated with adalimumab who developed immune-mediated necrotizing myopathy (IMNM) and trigeminal neuropathy after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination. Trigeminal neuralgia and elevated serum creatine kinase levels emerged 12 days post-vaccination, followed by myalgia in the femoral muscles. IMNM was histologically diagnosed. The pathogenesis may involve molecular mimicry between the SARS-CoV-2 spike glycoprotein and autologous tissues triggered by vaccination. This case emphasizes the association between SARS-CoV-2 vaccination, tumor necrosis factor inhibitor, IMNM, and trigeminal neuropathy, as well as the importance of monitoring immune-mediated adverse events following SARS-CoV-2 vaccination in patients with autoimmune disease.

We aimed to describe the association between trigeminal nerve (TN) dose and toxicity and determine a threshold value that leads to TN toxicity in patients with parotid tumors treated with adjuvant conventional fractionated radiation therapy.
Eighteen patients who underwent adjuvant radiotherapy (RT) between 2013 and 2018 were included in this retrospective study. TN and its branches were outlined subsequently on the planning CT scans. The doses received by TN were obtained based on the dose-volume histogram. The dose and toxicity relationship was investigated over the total prescribed dose. RT-related toxicity was graded according to Common Terminology Criteria for Adverse Events V4.0 (CTCAEv4.0).
The median follow-up was 29.5 months. After RT, 61% of patients had Grade I-II late TN toxicity divided into Grade I in 4 (22%) and Grade II in 7 (39%) patients. TN injury symptoms were as follows: loss of sensation in the chin area in 3, difficulty in jaw movements in 3, and paresthesia in 5 patients. The total RT dose (p = 0.001), Dmax (p = 0.001), PTV-TN Dmax (p = 0.001), D1cc (p = 0.004), D0.5cc (p = 0.001), and D0.1cc (p = 0.01) had a significant effect on TN toxicity. Cut-off values leading to toxicity were determined as 66, 65.5, 65.25, 63.6, and 62.7 Gy for Dmax, PTV-TN Dmax, D0.1cc, D 0.5cc, and D1cc, respectively.
Radiation-induced TN injury in head and neck cancer patients may further be investigated in clinically prospective trials by virtue of high toxicity rates with current RT doses in our retrospectively designed dosimetric study in parotid tumors.

Introduction  Trigeminal schwannomas (TS) are rare skull base tumors that have been associated with significant neuropathic sequalae for patients. The authors aim to evaluate the clinical features, treatment outcomes, and neuropathic sequelae following endoscopic endonasal approach (EEA) for TS. Methods  The study involves a retrospective review of patients who underwent EEA for resection of TS at a single academic institution between 2004 and 2020. Radiographic and clinical data were recorded and analyzed. Results  A total of 16 patients were abstracted, with a mean age at the time of surgery of 44 years with a slight female (1.83:1) predominance. Primary preoperative symptomatology included facial pain/neuralgia ( n  = 5, 31.3%), facial hypoesthesia ( n  = 4, 25.0%), and headache ( n  = 4, 25.0%). Following TS resection, patients were found to have facial hypoesthesia ( n  = 11, 68.8%), neuropathic keratopathy ( n  = 4, 25.0%), and mastication musculature atrophy ( n  = 3, 18.8%). Patients with preoperative facial pain/neuralgia ( n  = 5, 31.3%) were significantly more likely to try adjunctive pain therapies ( p  = 0.018) as well as seek pain consultation ( p  = 0.018). Patients with preoperative migraines ( n  = 2, 12.5%) were significantly more likely to trial adjunctive pain therapies ( p  = 0.025) and undergo evaluation with pain specialists ( p  = 0.025). Finally, patients with preoperative pharmacologic agent utilization were significantly more likely to trial adjunctive pain therapies ( p  = 0.036) and pursue pain consultation ( p  = 0.036). Conclusion  Some degree of trigeminal dysfunction may be more common than previously reported following EEA for TS resection. Factors that appear to play a role in the development of trigeminal dysfunction include pre-existing pain syndromes such as facial pain/neuralgia or headache and preoperative medication utilization.

UNASSIGNED: Craniofacial pain (CFP) poses a burden on patients and health care systems. It is hypothesized that ketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist, can reverse central sensitization associated with causation and propagation of CFP. This systematic review aims to assess the role of ketamine for CFP.
UNASSIGNED: Databases were searched for studies published up to September 26, 2022, investigating the efficacy of ketamine for adults with CFP. Primary outcome was the change in pain intensity at 60 min postintervention. Two reviewers screened and extracted data. Registration with PROSPERO was performed (CRD42020178649).
UNASSIGNED: Twenty papers (six randomized controlled trials [RCTs], 14 observational studies) including 670 patients were identified. Substantial heterogeneity in terms of study design, population, dose, route of administration, treatment duration, and follow-up was noted. Bolus dose ranged from 0.2-0.3 mg/kg (intravenous) to 0.4 mg/kg (intramuscular) to 0.25-0.75 mg/kg (intranasal). Ketamine infusions (0.1-1 mg/kg/h) were given over various durations. Follow-up was short in RCTs (from 60 min to 72 h) but longer in observational studies (up to 18 months). Ketamine by bolus treatment failed to reduce migraine intensity but had an effect by reducing intensity of aura, cluster headache (CH), and trigeminal neuralgia. Prolonged ketamine infusions showed sustainable reduction of migraine intensity and frequency of CH attacks, but the quality of the evidence is low.
UNASSIGNED: Current evidence remains conflicting on the efficacy of ketamine for CFP owing to low quality and heterogeneity across studies. Ketamine infusions are suggested to provide sustained improvement, possibly because of prolonged duration and higher dosage of administration. RCTs should focus on the dose-response relationship of prolonged ketamine infusions on CFP.
Contexte: La douleur crânio-faciale représente un fardeau pour les patients et les systèmes de soins de santé. L’hypothèse a été émise que la kétamine, un antagoniste du récepteur N-méthyl-D-aspartate (NMDA), peut inverser la sensibilisation centrale associée à la causalité et à la propagation de la douleur crânio-faciale. Cette revue systématique vise à évaluer le rôle de la kétamine dans la douleur crânio-faciale.Méthodes: Les bases de données ont été consultées pour y repérer les études publiées jusqu’au 26 septembre 2022 qui portaient sur l’efficacité de la kétamine chez les adultes atteints de douleur crânio-faciale. Le critère de jugement principal était le changement de l’intensité de la douleur 60 minutes après l’intervention. Deux évaluateurs ont examiné et extrait les données. L’inscription auprès de PROSPERO a été réalisée (CRD42020178649).Résultats: Vingt articles (six essais contrôlés randomisés, 14 études observationnelles) incluant 670 patients ont été répertoriées. Une hétérogénéité considérable en matière de devis d’étude, de population, de dose, de voie d’administration, de durée du traitement et de suivi a été notée. La dose bolus variait de 0,2 à 0,3 mg/kg (voie intraveineuse) à 0,4 mg/kg (voie intramusculaire) et à 0,25-0,75 mg/kg (voie intranasale). Les perfusions de kétamine (0,1-1 mg/kg/h) étaient administrées sur différentes durées. Le suivi était court dans les études contrôllées randomisées (de 60 min à 72 h) mais plus long dans les études observationnelles (jusqu’à 18 mois). La kétamine par traitement bolus n’a pas réussi à réduire l’intensité de la migraine mais a eu un effet en réduisant l’intensité de l’aura, la céphalée en grappe et la névralgie du trijumeau. Les perfusions de kétamine prolongées ont montré une réduction durable de l’intensité de la migraine et la fréquence des crises de CH, mais la qualité des données probantes est faible.Conclusions: Les données probantes actuelles demeurent contradictoires sur l’efficacité de la kétamine pour la douleur crânio-faciale en raison de la faible qualité et de l’hétérogénéité des études. Il est suggéré que les perfusions de kétamine procurent une amélioration soutenue, peut-être en raison de leur durée prolongée et de leur posologie d’administration plus élevée. Les essais contrôlés randomisés devraient se concentrer sur la relation dose-réponse des perfusions prolongées de kétamine sur la douleur crâno-faciale.

Trigeminal neuralgia is a pain syndrome that is defined by sharp electrical shock-like pain that radiates in the sensory distribution of the trigeminal nerve. The classical cause of this syndrome is vascular compression, but other causes, such as stroke, have also been described. Instances of post-ischemic trigeminal pain have been described as meeting the classic description, and are termed trigeminal neuropathy. The treatment paradigms for trigeminal neuralgia versus neuropathy differ significantly, especially with the consideration of surgical management.We present a case of a 78-year-old man with post-ischemic trigeminal neuropathy that was successfully treated with radiofrequency ablation after failure of conservative management.We also summarize three previous cases of post-ischemic trigeminal neuropathy that were also successfully treated with percutaneous surgical treatment, showing that percutaneous surgical management should be considered in patients with post-ischemic trigeminal neuropathy that fail conservative management.

Trigeminal neuralgia is a chronic pain condition associated with sharp, shock-like pain in one or more divisions of the trigeminal nerve. For patients who do not respond well to pharmacotherapy, there is growing evidence that Botulinum toxin type A injections into the trigeminal ganglion provide pain relief for several weeks up to several months at a time. One option is to administer injections into the trigeminal ganglion in Meckel\'s cave by inserting a needle through the Pterygopalatine Fossa using fluoroscopy to guide and confirm the proper needle placement. However, there is evidence that Botulinum toxin travels across nerve synapses; thus, injecting directly into the trigeminal ganglion may not be necessary. We present two patients with a confirmed diagnosis of trigeminal neuralgia who were treated by injecting Botulinum toxin type A intraorally into the mental foramen which resulted in 6 months or longer of pain relief. Injections into the mental foramen are much easier to administer than those administered directly into the trigeminal ganglion, and both patients treated with this technique experienced comparable results to what can be expected from traditional fluoroscopy-guided botulinum toxin injections. Though more research is needed, these cases potentially imply that a less-invasive injection may be sufficient in managing trigeminal neuralgia-related pain.

BACKGROUND: Vaccines against coronavirus disease 2019 have a high level of efficacy and safety across all populations. However, numerous case series have been published on neurological disorders, including Bell\'s palsy, Guillain-Barre syndrome, transverse myelitis, and multiple sclerosis. The authors presented a case of trigeminal neuropathy after coronavirus vaccination in a patient who had undergone microvascular decompression (MVD) for trigeminal neuralgia (TN).
METHODS: A 77-year-old woman presented with acute trigeminal neuropathy after receiving a Pfizer-BioNtech vaccination (tozinameran) against severe acute respiratory syndrome coronavirus 2. The patient had undergone MVD for TN and the facial pain completely disappeared. One month later, she received the first injection of the tozinameran vaccine. Twelve hours after vaccination, she presented with numbness and pain induced by touching any place on the entire right face. No eruption was observed on her face. The serum herpes zoster virus antibodies were confirmed within the normal range. Magnetic resonance imaging revealed no abnormalities. The authors suspected a right trigeminal neuropathy after vaccination. Administration of carbamazepine and pregabalin improved TN but facial numbness persisted, especially in the mandibular division.
CONCLUSIONS: The coronavirus is a possible etiology of secondary trigeminal neuropathy in the case of MVD for TN.