Pain is a common symptom associated with many disorders affecting the craniofacial tissues that include the teeth and their supporting structures, the jaw, face and tongue muscles, and the temporomandibular joint. Most acute craniofacial pain states are easily recognized and readily treated, but chronic craniofacial pain states (e.g., temporomandibular disorders [TMD], trigeminal neuropathies, and some headaches) may be especially challenging to manage successfully. This chapter provides an overview of the processes that underlie craniofacial pain, with a focus on the pain-modulatory mechanisms operating in craniofacial tissues and in the central nervous system (CNS), including the role of endogenous chemical processes such as those involving opioids. The chapter outlines in particular findings from preclinical studies that have provided substantial information about the neural as well as nonneural (e.g., glial) processes involved in the initiation, transmission, and modulation of nociceptive signals in the trigeminal system, and also draws attention to their clinical correlates. The increased understanding gained from these preclinical studies of how nociceptive signals can be modulated will contribute to improvements in presently available therapeutic approaches to manage craniofacial pain as well as to the development of novel analgesic approaches.

OBJECTIVE: The distribution characteristics of intrathecal drugs and the limitation of current catheterization techniques make traditional intrathecal analgesic treatment nearly useless for refractory craniofacial pain, such as trigemina neuralgia. This technical guideline aims to promote the widespread and standardize the application of intra-prepontine cisternal drug delivery via spinal puncture and catheterization.
METHODS: A modified Delphi approach was used to work for this guideline. On the issues related to the intra-prepontine cisternal targeted drug delivery technique, the working group consulted 10 experts from the field with 3 rounds of email feedback and 3 rounds of conference discussion.
RESULTS: For the efficacy and safety of the intra-prepontine cisternal targeted drug delivery technique, a consensus was formed on 7 topics (with an agreement rate of more than 80%), including the principles of the technique, indications and contraindications, patient preparation, surgical specifications for intra-prepontine cisternal catheter placement, analgesic dosage coordination, analgesic management, and prevention and treatment of complications.
CONCLUSIONS: Utilizing the intra-prepontine cisternal drug infusion system to manage refractory craniofacial pain could provide advantages in terms of minimally invasive, secure, and effective treatment. This application can not only alleviate the suffering of individuals experiencing the prolonged pain but also support the maintenance of quality of life and dignity in their final moments, justifiing its widespread dissemination and standardized adoption in domestic and international professional fields.
目的: 鞘内镇痛药物的分布特点和目前置管技术的限制使传统的鞘内镇痛方法对头面部难治性疼痛无法发挥作用。本技术应用指南的制订旨在促进经脊柱椎间隙穿刺蛛网膜下腔脑桥前池置管药物输注技术的推广和规范、安全应用。方法: 工作小组采用改良德尔菲法，邀请本技术领域的10名专家对脑桥前池药物输注技术的相关议题进行3轮电子邮件函询及3轮现场会议讨论。结果: 针对脑桥前池药物输注技术的有效性和安全性，在技术原理、适应证和禁忌证、患者准备、脑桥前池置管手术规范、镇痛药物选择和剂量衔接、术后镇痛管理和并发症防治共7个议题形成一致意见(同意率≥80%)。结论: 脑桥前池药物输注镇痛技术应用于头面部难治性疼痛患者具有微创、安全、有效的优点，既可减轻长期罹受疼痛患者的痛苦，也能帮助一些患者保持人生最后一程的生活质量和生命尊严，值得在国内外相关专业领域推广和规范应用。.

UNASSIGNED: Stereotactic radiosurgery (SRS) has recently gained space as an accepted non-invasive alternative treatment option for drug resistant Glossopharyngeal neuralgia (GPN). The purpose of this systematic review was to provide an overview of the outcomes of SRS treatment in patients with GPN.
UNASSIGNED: A literature review until March 2023 was performed. Data about patient\'s demographics, complications and recurrence rates, additional treatment post procedure as well as pain outcomes in the short and long term were collected. Studies without reported pain outcomes were excluded.
UNASSIGNED: Sixteen studies with a total of 97 patients diagnosed with GPN who had undergone SRS were identified. The mean reported maximal radiation dose ranged from 70 to 88.7 Gy with the glossopharyngeal meatus (GPM) being the most common target in 12/16 studies. The median time from SRS till pain response was between 2 and 120 days. The mean proportion of patients requiring further treatment after SRS ranged from 11.1 to 57.14% in a time frame between 2 and 36 months post procedure. Favourable pain response rates after SRS (BNI-IIIb) ranged from 60% to 100% and 57.1%-100% in short and long term respectively.
UNASSIGNED: SRS for GPN remains a safe alternative to surgery with low complication rates and favourable pain outcomes in both short and long term.

Craniofacial pain syndromes exhibit a high prevalence in the general population, with a subset of patients developing chronic pain that significantly impacts their quality of life and results in substantial disabilities. Anatomical and functional assessments of the greater occipital nerve (GON) have unveiled its implication in numerous craniofacial pain syndromes, notably through the trigeminal-cervical convergence complex. The pathophysiological involvement of the greater occipital nerve in craniofacial pain syndromes, coupled with its accessibility, designates it as the primary target for various interventional procedures in managing craniofacial pain syndromes. This educational review aims to describe multiple craniofacial pain syndromes, elucidate the role of GON in their pathophysiology, detail the relevant anatomy of the greater occipital nerve (including specific intervention sites), highlight the role of imaging in diagnosing craniofacial pain syndromes, and discuss various interventional procedures such as nerve infiltration, ablation, neuromodulation techniques, and surgeries. Imaging is essential in managing these patients, whether for diagnostic or therapeutic purposes. The utilization of image guidance has demonstrated an enhancement in reproducibility, as well as technical and clinical outcomes of interventional procedures. Studies have shown that interventional management of craniofacial pain is effective in treating occipital neuralgia, cervicogenic headaches, cluster headaches, trigeminal neuralgia, and chronic migraines, with a reported efficacy of 60-90% over a duration of 1-9 months. Repeated infiltrations, neuromodulation, or ablation may prove effective in selected cases. Therefore, reassessment of treatment response and efficacy during follow-up is imperative to guide further management and explore alternative treatment options. Optimal utilization of imaging, interventional techniques, and a multidisciplinary team, including radiologists, will ensure maximum benefit for these patients.

BACKGROUND: Intractable postherpetic neuralgia (PHN) can be difficult to manage even with aggressive multimodal therapies. Patients who experience uncontrolled refractory cranial PHN despite conservative treatment may benefit from an intrathecal drug delivery system (IDDS). For craniofacial neuropathic pain, the traditional approach has been to place the intrathecal catheter tip below the level of the cranial nerve root entry zones, which may lead to insufficient analgesia.
METHODS: We describe a 69-year-old man with a 1-year history of PHN after developing a vesicular rash in the ophthalmic division of cranial nerve V (trigeminal nerve) distribution. The pain was rated 7-8 at rest and 9-10 at breakthrough pain (BTP) on a numeric rating scale. Despite receiving aggressive multimodal therapies including large doses of oral analgesics (gabapentin 150 mg q12 h, oxycodone 5 mg/acetaminophen 325 mg q6 h, and lidocaine 5% patch 700 mg q12 h) and sphenopalatine ganglion block, there was no relief of pain. Subsequently, the patient elected to have an implantable IDDS with the catheter tip placed at the interpeduncular cistern. The frequency of BTP episodes decreased. The patient\'s continuous daily dose was adjusted to 0.032 mg/d after 3 mo of follow-up and stopped 5 mo later. He did not report pain or other discomfort at outpatient follow-up 6 mo and 1 year after stopping intracisternal hydromorphone.
CONCLUSIONS: The use of interpeduncular cistern intrathecal infusion with low-dose hydromorphone by IDDS may be effective for severe craniofacial PHN.

BACKGROUND: Headaches (HAs) and temporomandibular joint dysfunction (TMD) are common comorbidities, and the presence of one of them in a patient increases the incidence of the other. The relationship between these 2 conditions may involve common pathophysiological processes. Considering the topicality of the problem, it is justified to conduct research in this field. In this study, we assessed HA type and severity in people with TMD.
OBJECTIVE: The aim of the study was to conduct qualitative and quantitative assessments of HAs in people with temporomandibular joint (TMJ) disorders.
METHODS: The study group consisted of 51 subjects of both sexes with a TMD diagnosed using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) test. A self-report questionnaire was utilized to self-assess the presence of TMD symptoms, while the standardized Short-Form of the McGill Pain Questionnaire was used to qualitatively and quantitatively assess HAs.
RESULTS: People with TMD were significantly more likely to report HA occurrences (p < 0.001). Pain intensity was statistically significantly higher among individuals with TMD compared to those without TMD symptoms (p < 0.001). Most often, the HA was associated with a pressing pain (r = 0.82) and least often, it was described as cutting (r = 0.30). Neck and shoulder girdle pain (p = 0.059; 82.9%) and clenching and/or grinding of teeth (p = 0.021; 92.7%) were significantly more common among patients who declared HAs than among those without HAs. The results obtained so far may indicate a significant relationship between HA and TMD.
CONCLUSIONS: We have described the relationship between the occurrence of HAs and TMD. Headaches are more frequent and more severe in people with TMD.

BACKGROUND: Chronic craniofacial pain can be difficult to manage clinically. This technical report documents the peripheral nerve stimulation of the C2 dorsal root ganglion as an effective modality to treat refractory atypical facial pain.
METHODS: In this case series, three patients with chronic refractory atypical facial pain and p >50% pain relief following diagnostic C2 dorsal root ganglion blockade underwent ultrasound-guided percutaneous placement of a peripheral nerve stimulator adjacent to the C2 dorsal root ganglion. Patients were then observed clinically and monitored for improvement in symptoms and adverse events.
RESULTS: Three patients underwent peripheral nerve stimulator placement. At follow-up, there were no reported adverse events, and all patients reported satisfactory improvement in pain.
CONCLUSIONS: The neuromodulation of C2 dorsal root ganglion via ultrasound-guided percutaneously implanted peripheral nerve stimulator is a novel and potentially effective approach for the management of chronic refractory craniofacial pain.

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.

UNASSIGNED: Wireless percutaneous nerve stimulation (PNS) for chronic pain is rapidly evolving in the ever expanding neuromodulation paradigm. Safety and lower risks with a potential of long-term analgesia cannot be over emphasised especially with the ongoing opioid pandemic. PNS with an implanted pulse generator (IPG) has also been shown to provide good benefit, without often unpleasant widespread paraesthesia from conventional spinal cord stimulators.
UNASSIGNED: We retrospectively extracted data on all wireless PNS implants in our highly specialised pain neuromodulation centre since initiation of wireless PNS service in August 2019. Patient demographics, pain history, analgesic intake and details on implant follow-up data within 1 year post-implant including pain relief, EuroQol-5 Dimension (EQ-5D) and Patients\' Global Impression of Change (PGIC) scores were extracted. The cases are presented in a narrative format.
UNASSIGNED: A total of five patients were implanted with wireless (Stimwave®) PNS from August 2019 to February 2020. Neuropathic pain was the most common presenting diagnosis. All patients showed >50% pain relief at 3 months. EQ-5D and PGIC did not show any improvement in the subjects. Two of the patients managed to decrease their analgesics after implantation. Similar sustained benefits could not be demonstrated after 1 year.
UNASSIGNED: PNS can provide analgesia in appropriately selected cases. Naivety of the technique and procedure might cause some degree of uncertainty. External pulse generator with wireless transmission avoids IPG and tunnelling related side effects, but requires individualised special wearable technology to power the lead. Minimally invasive nature of the technique might be attractive and preferable for patients with complex medical issues, nickel allergy and poor general health who may otherwise be unsuitable for Spinal Cord Stimulation (SCS) with conventional hardware. Robust prospective controlled studies and RCTs in future might provide further insights on utility in other neuropathic pain diagnosis, long-term outcomes and acceptability compared to conventional SCS.

Peripheral nerve stimulation (PNS) is a powerful interventional option for the management of otherwise intractable pain. This technique involves the implantation of electrodes to apply electrical stimulation to named peripheral nerves, thereby alleviating pain in the territory of the target nerves. Recent advancements, largely driven by physician-industry relationships, have transformed the therapy into one that is minimally invasive, safe, evidence-based, and effective. Ongoing research has expanded the indications beyond chronic neuropathic pain in a peripheral nerve distribution. This article provides an overview of recent advances in this field.