Ultrasound-Guided Intervention for Treatment of Trigeminal Neuralgia: An Updated Review of Anatomy and Techniques

Awake neurosurgery: Advancements in microvascular decompression for trigeminal neuralgia

Background

The treatment landscape for trigeminal neuralgia (TN) involves various surgical interventions, among which microvascular decompression (MVD) stands out as highly effective. While MVD offers significant benefits, its success relies on precise surgical techniques and patient selection. In addition, the emergence of awake surgery techniques presents new opportunities to improve outcomes and minimize complications associated with MVD for TN.

Methods

A thorough review of the literature was conducted to explore the effectiveness and challenges of MVD for TN, as well as the impact of awake surgery on its outcomes. PubMed and Medline databases were searched from inception to March 2024 using specific keywords "Awake Neurosurgery," "Microvascular Decompression," AND "Trigeminal Neuralgia." Studies reporting original research on human subjects or preclinical investigations were included in the study.

Results

This review highlighted that MVD emerges as a highly effective treatment for TN, offering long-term pain relief with relatively low rates of recurrence and complications. Awake surgery techniques, including awake craniotomy, have revolutionized the approach to MVD, providing benefits such as reduced postoperative monitoring, shorter hospital stays, and improved neurological outcomes. Furthermore, awake MVD procedures offer opportunities for precise mapping and preservation of critical brain functions, enhancing surgical precision and patient outcomes.

Conclusion

The integration of awake surgery techniques, particularly awake MVD, represents a significant advancement in the treatment of TN. Future research should focus on refining awake surgery techniques and exploring new approaches to optimize outcomes in MVD for TN.

A Comparison Between the Efficacy of Trigeminal Ganglion Radiofrequency Thermocoagulation and Ultrasound-Guided Maxillary-Mandibular Nerve Pulsed Radiofrequency in the Treatment of Trigeminal Neuralgia: A Randomized Clinical Trial

Background and objective Trigeminal neuralgia (TN) is a debilitating disorder characterized by acute episodic attacks of pain that significantly impair patients' quality of life and overall functioning. Initial therapeutic strategies to treat this condition include pharmacological options, particularly carbamazepine. In cases with resistance to dose escalation and polypharmacy, interventional procedures may be warranted. The primary aim of this study was to compare the efficacy of trigeminal ganglion (TG) radiofrequency thermocoagulation (RFT) and ultrasound (US)-guided maxillary/mandibular (max/mand) nerve pulsed radiofrequency (PRF) for treating TN, based on the findings at six months post-treatment. The secondary aims were to assess the impact of these interventions on drug consumption and interventional safety based on adverse events. Methods This prospective, randomized, single-blind study was conducted at a single pain clinic. Forty-four patients were randomized into two groups. Group RFT received TG RFT at 60 °C, 65 °C, and 70 °C for 60 seconds each, whereas Group PRF received max/mand PRF for 240 seconds. Pain relief was assessed by using the numeric rating scale (NRS) and intervention effectiveness on medication consumption was evaluated by using the Medication Quantification Scale III (MQS III). The rates of intervention-related adverse events were also compared. Results Both RFT and PRF significantly alleviated pain at one and six months post-treatment compared to baseline (p<0.05). No statistical differences were found in the NRS and MQS III scores between the groups. At six months, 77.3% of RFT patients and 63.9% of PRF patients experienced at least 50% pain relief, with no statistically significant difference. Hypoesthesia occurred in two RFT patients, and masseter weakness was observed in one patient, while no adverse events were reported in the PRF group. Conclusions TG RFT and max/mand PRF are effective treatments for TN. US-guided max/mand PRF, which avoids RFT-associated complications and radiation exposure, may be the superior and preferable option. In this study, the potential space between the coronoid process and maxilla was used to access the maxillary nerve during the maxillary block and PRF procedures, in contrast to the classical approach through the mandibular notch. Further large-scale randomized controlled trials are required to gain deeper insights into the topic.

Trigeminal Postherpetic Neuralgia: From Pathophysiology to Treatment

PURPOSE OF REVIEW

Trigeminal postherpetic neuralgia (TG-PHN) is a neuropathic pain condition complicating herpes zoster (HZ) attributed to the trigeminal nerve. It poses significant challenges due to its persistent and debilitating nature. This review explores the clinical characteristics of TG-PHN, analyzes its pathophysiological underpinnings, and addresses existent and potential therapies.

RECENT FINDINGS

TG-PHN is one of the most common and complex PHN locations. It has distinguishing clinical and pathophysiological characteristics, starting with viral triggered injuries to the trigeminal ganglion (TG) and peripheral tissue and involving the ascending and descending brain modulation pathways. Current therapies include vaccines, oral and topical medications, and interventional approaches, like nerve blocks and neurostimulation. This review covers TG-PHN's clinical and physiological components, treatment options, and potential future targets for improved management. By exploring the complexities of this condition, we aim to contribute to developing more effective and targeted therapies for patients suffering from trigeminal PHN.

Ultrasound-Guided Combined Greater Occipital Nerve Block at the C2 Level with Trapezius Trigger Point Injection and Supraorbital-Supratrochlear Nerve Block: More Effective on Allodynia and Disability in Chronic Migraine

Background

Chronic migraine (CM) patients with cutaneous allodynia (CA) show a poor response to treatment. Long-term studies have yet to be conducted to demonstrate the efficacy of blocks on CA. This study evaluated the improvement in allodynia and disability in CM treated with ultrasound (US)-guided blocks.

Methods

In this prospective, non-randomized comparative study, 60 CM patients with CA were evaluated for the clinical effectiveness of the therapy using the numeric rating scale (NRS), headache impact test-6 (HIT-6), brush allodynia test, and allodynia symptom checklist (ASC-12). At the first visit, tenderness in the nerve or trapezius muscle was confirmed in the intervention group. US-guided greater occipital nerve block (GONB), GONB, and trapezius muscle injection (TPI), or GONB, TPI, and peripheral trigeminal nerve block (PTNB), respectively, were performed four times once a week for a month. Initial and third-month assessments were performed.

Results

The ASC-12 scores decreased in the GONB+TPI+PTNB and GONB groups more than the GONB+TPI group (mean rank, respectively, 26.86, 27.40, 38.39; P = 0.018). The decrease in HIT-6 scores was greater in the GONB+TPI+PTNB group than in the GONB group (mean rank, respectively, 21.98, 39.95, P < 0.017) in the first month. In the third month, the GONB+TPI+PTNB group scored HIT-6 significantly lower than GONB and GONB+TPI (mean rank: 18.84, 38.73, 35.61; P < 0.001).

Conclusions

GONB+TPI+PTNB was more successful in alleviating allodynia and disability.

Non-Surgical Treatments of Trigeminal Neuralgia from the Perspective of a Pain Physician: A Narrative Review

Trigeminal neuralgia (TN) is a unilateral disorder characterized by electric shock-like pain, abrupt onset and termination, and limited to one or more branches of the trigeminal nerve. Various therapeutic modalities for TN have been introduced. We searched for literature indexed in PubMed, Medline, and the National Library of Medicine and reviewed all relevant articles on non-surgical treatments for TN. Published studies were reviewed with no restrictions on date; reviews, clinical trials, animal studies, retrospective studies, and cases were included. Carbamazepine and oxcarbazepine are the recommended first-line pharmacotherapies. Interventional treatments should be considered when pharmacotherapy is insufficient or withdrawn because of adverse effects.

Pulsed Radiofrequency for Postherpetic Trigeminal Neuralgia: A Case Report

Trigeminal postherpetic neuralgia has been reported to cause chronic headaches and facial pain. There are various modalities of treatment ranging from pharmacological to surgical treatment. However, these are frequently accompanied by undesirable side effects and minimal efficacy. Pulsed radiofrequency has been used to treat chronic pain but it is often seen as an unconventional treatment for postherpetic neuralgia. Nonetheless, the literature supports its use for alleviating pain with minimal complications. This case demonstrates that pulsed radiofrequency can successfully treat intractable pain secondary to postherpetic neuralgia affecting all three trigeminal dermatomes.

Ultrasound Imaging of Facial Vascular Neural Structures and Relevance to Aesthetic Injections: A Pictorial Essay

The facial and submental regions are supplied by complicated neurovascular networks; therefore, facial aesthetic injections may be associated with serious adverse events such as skin necrosis and blindness. Pre-injection localization of neurovascular structures using high-resolution ultrasound can theoretically prevent unexpected complications. Therefore, a systematic protocol that focuses on these facial neurovascular structures is warranted. In this pictorial essay, we discuss the sonoanatomy of facial and submental neurovascular structures and its relevance to aesthetic injections. Moreover, we have highlighted the mechanisms underlying potential neurovascular injuries during aesthetic injections.

A Novel Pain Relief Approach for the Treatment of Multiple Dental Caries and Pulpitis

Anxiety and stress toward treatment can hamper treatment completion in patients with dental caries and pulpitis. Therefore, effective management of post-treatment pain is important because poor pain management can lead to patient dissatisfaction. Ultrasound-guided nerve blocks provide good postoperative analgesia in maxillofacial surgeries. These surgeries can be performed under general or local anesthesia without complications. Here, we present the case of a patient with dental phobia who was successfully treated with these techniques. The patient was a 22-year-old woman with a history of manic-depressive illness who presented with 23 decayed teeth. She had previously undergone vital pulp therapy; however, post-treatment pain led to treatment-related stress, and the patient discontinued the dental treatment. She preferred the dental treatment to be completed with as little pain as possible and wanted to avoid a pulpectomy. The patient’s history of heavy use of non-steroidal anti-inflammatory drugs (NSAIDs) made her resistant to NSAIDs. As a result, the analgesic effect of NSAIDs could not be expected. After intravenous midazolam and propofol sedation, an ultrasound-guided inferior alveolar nerve block was performed bilaterally, and 0.375% ropivacaine was used as a local anesthetic. The patient did not complain of post-operative pain, and no post-operative analgesics were required.

Ultrasound Imaging of the Facial Muscles and Relevance with Botulinum Toxin Injections: A Pictorial Essay and Narrative Review

High-resolution ultrasound is preferred as the first-line imaging modality for evaluation of superficial soft tissues, such as the facial muscles. In contrast to magnetic resonance imaging and computed tomography, which require specifically designated planes (axial, coronal and sagittal) for imaging, the ultrasound transducer can be navigated based on the alignment of facial muscles. Botulinum toxin injections are widely used in facial cosmetic procedures in recent times. Ultrasonography is recognized as a useful tool for pre-procedure localization of target muscles. In this pictorial review, we discuss the detailed sonoanatomy of facial muscles and their clinical relevance, particularly with regard to botulinum toxin injections. Furthermore, we have summarized the findings of clinical studies that report ultrasonographic imaging of facial muscles.

Application of ultrasound guidance in the oral and maxillofacial nerve block

Introduction

Nerve block technology is widely used in clinical practice for pain management. Conventional nerve localization methods, which only rely on palpation to identify anatomical landmarks, require experienced surgeons and can be risky. Visualization technologies like ultrasound guidance can help prevent complications by helping surgeons locate anatomical structures in the surgical area and by guiding the operation using different kinds of images. There are several important and complex anatomical structures in the oral and maxillofacial regions. The current article reviews the application of ultrasound guidance in oral and maxillofacial nerve blocks.

Methods

We searched the literature on the use of ultrasound guidance for the main nerve block techniques in the oral and maxillofacial regions using both PubMed and MEDLINE and summarized the findings.

Results and Discussion

A review of the literature showed that ultrasound guidance improves the safety and effectiveness of several kinds of puncture procedures, including nerve blocks. There are two approaches to blocking the mandibular nerve: intraoral and extraoral. This review found that the role of ultrasound guidance is more important in the extraoral approach. There are also two approaches to the blocking of the maxillary nerve and the trigeminal ganglion under ultrasound guidance: the superazygomatic approach and the infrazygomatic approach. The infrazygomatic approach can be further divided into the anterior approach and the posterior approach. It is generally believed that the anterior approach is safer and more effective. This review found that the effectiveness and safety of most oral and maxillofacial nerve block operations can be improved through the use of ultrasound guidance.

Trigeminal Neuralgia: Current Approaches and Emerging Interventions

Trigeminal neuralgia (TN) has been described in the literature as one of the most debilitating presentations of orofacial pain. This review summarizes over 150 years of collective clinical experience in the medical and surgical treatment of TN. Fundamentally, TN remains a clinical diagnosis that must be distinguished from other types of trigeminal neuropathic pain and/or facial pain associated with other neuralgias or headache syndromes. What is increasingly clear is that there is no catch-all medical or surgical intervention that is effective for all patients with trigeminal neuralgia, likely reflective of the fact that TN is likely a heterogenous group of disorders that jointly manifests in facial pain. The first-line treatment for TN remains anticonvulsant medical therapy. Patients who fail this have a range of surgical options available to them. In general, microvascular decompression is a safe and effective procedure with immediate and durable outcomes. Patients who are unable to tolerate general anesthesia or whose medical comorbidities preclude a suboccipital craniectomy may benefit from percutaneous methodologies including glycerol or radiofrequency ablation, or both. For patients with bleeding diathesis due to blood thinning medications who are ineligible for invasive procedures, or for those who are unwilling to undergo open surgical procedures, radiosurgery may be an excellent option-provided the patient understands that maximum pain relief will take on the order of months to achieve. Finally, peripheral neurectomies continue to provide an inexpensive and resource-sparing alternative to pain relief for patients in locations with limited economic and medical resources. Ultimately, elucidation of the molecular mechanisms underlying trigeminal neuralgia will pave the way for novel, more effective and less invasive therapies.

Reduced Pain and Opioid Use in the Early Postoperative Period in Patients Undergoing a Frontotemporal Craniotomy under Regional vs General Anesthesia

INTRODUCTION

This study compares the postsurgical course of frontotemporal craniotomies conducted "awake" under regional anesthesia (RA) versus "asleep" under general anesthesia (GA) to investigate postoperative recovery, pain, opioid use, and anesthesia-related side effects.

METHODS

We retrospectively reviewed craniotomies for supratentorial, intra-axial tumors with frontotemporal exposure. Chronic opioid use and emergent cases were excluded. Primary outcomes included pain scores on a 0-10 numerical rating scale, opioid use as oral morphine milligram equivalence, first time to opioid use, nausea, and sedation on the Richmond Agitation and Sedation Scale (RASS). Secondary outcomes included postoperative seizures, Karnofsky Performance Scale (KPS) status, and hospital length of stay (LOS).

RESULTS

A total of 91 patients met inclusion criteria: 56 underwent a craniotomy under RA versus 35 under GA. Demographics and operative characteristics were similar between cohorts. A significant reduction in both postoperative pain and opioid use was observed among RA versus GA (first postoperative pain score 2 vs. 5, P < 0.01; postoperative day [POD] 0 median pain score 2.5 vs. 4, P < 0.01; POD 0 mean opioid in mg 14.49 vs. 24.43, P < 0.01). The time until patients requested opioids for pain after surgery was prolonged for RA versus GA [mean 7.23 vs. 3.42 hours, P < 0.01). Somnolence (RASS < 0) on POD 0 was significantly reduced among RA versus GA, with 23% versus 43%. Both cohorts had equivocal postsurgical outcomes such as seizures, KPS, and hospital LOS.

CONCLUSIONS

Frontotemporal craniotomy under RA during awake craniotomies provides better pain control, a reduction in opioid use, and less somnolence in the early postoperative period.

Lidocaine injections to the otic ganglion for the treatment of tinnitus-A pilot study

Tinnitus is defined as the perception of noise without an external acoustic stimulus. Due to the heterogeneity of tinnitus, no treatment has proven equally beneficial to every single of these patients. Previous studies have shown that trigeminal input can interfere with the perception of tinnitus. Therefore, we aimed to explore the therapeutic potential of lidocaine injections in trigeminal structures. We conducted a pilot study with 19 participants to explore feasibility and tolerability of this approach. The intervention consisted of three injections of lidocaine in the anatomical area of the trigeminal ganglion and the ganglion oticum via an oral approach corresponding to the affected side of tinnitus. We performed an assessment that included the Mini-TQ, CGII, and numeric rating scales of tinnitus loudness and severity at different time points over a follow-up period of 12 weeks. In addition to changes of subjective tinnitus complaints, potential adverse events were documented. Patients were treated at the Centre of Otorhinolaryngology in Traunstein, Germany, and data were analyzed at the University of Regensburg, Germany. We did not observe any relevant side effects. There was a significant reduction of tinnitus distress (Mini-TQ, Tinnitus severity) and loudness (measured subjectively) over time. Our pilot data suggests that lidocaine injections targeting trigeminal structures may be able to reduce tinnitus complaints. Future studies should investigate the effects of lidocaine injections in placebo-controlled trials in an extended sample size to further explore the potential benefits of this therapeutic approach on tinnitus.

Retrospective Study on Ganglionic and Nerve Block Series as Therapeutic Option for Chronic Pain Patients with Refractory Neuropathic Pain

Objective

Current recommendations controversially discuss local infiltration techniques as specific treatment for refractory pain syndromes. Evidence of effectiveness remains inconclusive and local infiltration series are discussed as a therapeutic option in patients not responding to standard therapy. The aim of this study was to investigate the effectiveness of infiltration series with techniques such as sphenopalatine ganglion (SPG) block and ganglionic local opioid analgesia (GLOA) for the treatment of neuropathic pain in the head and neck area in a selected patient group.

Methods

In a retrospective clinical study, 4960 cases presenting to our university hospital outpatient pain clinic between 2009 and 2016 were screened. Altogether, 83 patients with neuropathic pain syndromes receiving local infiltration series were included. Numeric rating scale (NRS) scores before, during, and after infiltration series, comorbidity, and psychological assessment were evaluated.

Results

Maximum NRS before infiltration series was median 9 (IQR 8–10). During infiltration series, maximum NRS was reduced by mean 3.2 points (SD 3.3, p < 0.001) equaling a pain reduction of 41.0% (SD 40.4%). With infiltration series, mean pain reduction of at least 30% or 50% NRS was achieved in 54.2% or 44.6% of cases, respectively. In six percent of patients, increased pain intensity was noted. Initial improvement after the first infiltration was strongly associated with overall improvement throughout the series.

Conclusion

This study suggests a beneficial effect of local infiltration series as a treatment option for refractory neuropathic pain syndromes in the context of a multimodal approach. This effect is both significant and clinically relevant and therefore highlights the need for further randomized controlled trials.

Efficacy and Safety of Percutaneous Ozone Injection Around Gasserian Ganglion for the Treatment of Trigeminal Neuralgia: A Multicenter Retrospective Study

Background

Ozone injection around Gasserian ganglion (OIAGG) has been reported to be an effective treatment for trigeminal neuralgia (TN); however, there remain areas for improvement. To overcome one of these limitations, a multicenter examination of application would be extremely helpful.

Objective

The goal of this report was to assess the efficacy of OIAGG for refractory TN across multiple centers and to explore factors predictive of successful treatment.

Design

A multicenter, retrospective study.

Setting

The study was conducted across 3 pain centers across China.

Patients and Methods

A total of 103 subjects from 3 pain centers were enrolled in the study. An ozone-oxygen mixture gas at a concentration of 30 µg/mL was injected into the area around the Gasserian ganglion performed under C-arm X-ray guidance. Primary outcome measures included a pain assessment using a visual analog scale (VAS) and the Barrow Neurological Institute (BNI) pain intensity scale. Clinical assessment of patients for these outcome measures was performed at pretreatment, post-treatment, 6 months, 1 year and 2 years after the OIAGG.

Results

Successful pain relief was defined as a score within BNI grades I–IIIa. The pain relief rates at post-treatment, 6 months, 1 year and 2 years after the procedure were 88.35%, 86.87%, 84.46% and 83.30%, respectively. The VAS at each observation time point was significantly different from the preoperative levels (P<0.05). Logistic regression analysis showed that previous nerve damage had a significant effect on the treatment results. No significant complications or side effects were found during or after treatment.

Conclusion

This multicenter research confirms our previous single center results that OIAGG is both effective and safe for patients with TN.

Technical considerations for approaches to the ultrasound-guided maxillary nerve block via the pterygopalatine fossa: a literature review

Background and objectives

Blockade of the trigeminal nerve and its branches is an effective diagnostic tool and potential treatment of facial pain. Ultrasound-guided injections in the pterygopalatine fossa (PPF) to block the trigeminal nerve divisions and sphenopalatine ganglion have been described but a consensus has yet to be reached over the ideal approach. We sought to delineate and compare the various approaches to the ultrasound-guided trigeminal divisions blockade via the PPF.

Methods

The literature search was performed by searching the National Library of Medicine’s PubMed database, the Cochrane Database of Systematic Reviews and Google Scholar within the date range of January 2009–March 2019 for keywords targeted toward “trigeminal nerve,” “maxillary nerve,” or “pterygopalatine fossa,” “ultrasound,” and “nerve block,” using an English language restriction. Six papers were included in the final review: one prospective double-blinded randomized controlled trial, one prospective descriptive study, one case series, two case reports, and one cadaveric study.

Results

There are three main approaches to the ultrasound-guided trigeminal nerve branches blockade via the PPF: anterior infrazygomatic in-plane, posterior infrazygomatic in-plane, and suprazygomatic out-of-plane approaches. Each showed injectate spread to the PPF in cadaver, adult and pediatric patients, respectively.1–5 Injectate used varied from 3 to 5 mL to 0.15 mL/kg.

Conclusions

These studies demonstrated that the PPF is a readily accessible target for the ultrasound-guided maxillary nerve block via three main approaches.2 The ideal approach is yet to be determined and must be further explored.

Ultrasound-guided glossopharyngeal nerve block via the styloid process for glossopharyngeal neuralgia: a retrospective study

Objective

To examine the effectiveness and safety of ultrasound-guided glossopharyngeal nerve block via the styloid process for primary glossopharyngeal neuralgia.

Methods

This retrospective study included all patients receiving glossopharyngeal nerve block via the styloid process under ultrasound guidance for primary glossopharyngeal neuralgia between January 2015 and May 2018 at our hospital. The primary outcome of the study was pain relief as assessed using the visual analog scale (VAS). Treatment was considered effective if the VAS score decreased by more than 2 points.

Results

Twelve patients were included in the analysis. The baseline VAS scores ranged from 5 to 9. All patients received previous pharmacotherapy. Other previous treatments included pulsed mode radiofrequency (n=4), microvascular decompression (n=2), and glossopharyngeal nerve block (not under ultrasound guidance; n=2). The patients completed a total of 48 injections for glossopharyngeal nerve block. At discharge from the hospital, and at 6, 12, and 18 months thereafter, 10/12, 10/12, 7/12, and 4/12 patients achieved pain relief and the effective rate was 83.3% at discharge, 83.3% at 6 months, 58.3% at 1 year, and 33.3% at 18 months, respectively.

Conclusion

Ultrasound-guided glossopharyngeal nerve block via the styloid process is a safe, radiation-free, repeatable, convenient, and effective treatment. It can provide a treatment option for patients with glossopharyngeal neuralgia.

Regional techniques for head and neck surgical procedures

Regional anesthesia has evolved as an important tool for anesthesiologists and surgeons managing patients for surgery of the head and neck region. In recent years, ultrasound use has increased significantly, and newer nerve blocks have been established for surgeries of the head and regions. In this review, anatomy, indications, efficacy, and potential side effects of regional anesthesia for the head and neck region are presented. Evolving practice strongly suggests that regional nerve blocks for the head and neck region are safe and effective. Future studies and education will likely evolve practice to make these regional techniques standards for future surgeries of the head and neck region.