Percutaneous radiofrequency thermocoagulation for trigeminal neuralgia using neuronavigation-guided puncture from a mandibular angle

Neuronavigation-Specific Parameters for Selective Access of Trigeminal Rootlets in Radiofrequency Lesioning: A Cadaveric Morphometric Study

BACKGROUND AND OBJECTIVE

Radiofrequency lesioning (RFL) is a safe and effective treatment for medically refractory trigeminal neuralgia. Despite gaining mainstream neurosurgical acceptance in the 1970s, the technique has remained relatively unchanged, with the majority of series using lateral fluoroscopy over neuronavigation for cannula guidance. To date, there are no studies describing neuronavigation-specific parameters to help neurosurgeons selectively target individual trigeminal rootlets. In this cadaveric study, we sought to provide a neuronavigation-specific morphometric roadmap for selective targeting of individual trigeminal rootlets.

METHODS

Embalmed cadaveric specimens were registered to cranial neuronavigation. Frontotemporal craniotomies were then performed to facilitate direct visualization of the Gasserian ganglion. A 19-gauge cannula was retrofit to a navigation probe, permitting real-time tracking. Using preplanned trajectories, the cannula was advanced through foramen ovale (FO) to the navigated posterior clival line (nPCL). A curved electrode was inserted to the nPCL and oriented inferolaterally for V3 and superomedially for V2. For V1, the cannula was advanced 5 mm distal to the nPCL and the curved electrode was reoriented inferomedially. A surgical microscope was used to determine successful contact. Morphometric data from the neuronavigation unit were recorded.

RESULTS

Twenty RFL procedures were performed (10R, 10L). Successful contact with V3, V2, and V1 was made in 95%, 90%, and 85% of attempts, respectively. Mean distances from the entry point to FO and from FO to the clival line were 7.61 cm and 1.26 cm, respectively.

CONCLUSION

In this proof-of-concept study, we found that reliable access to V1-3 could be obtained with the neuronavigation-specific algorithm described above. Neuronavigation for RFL warrants further investigation as a potential tool to improve anatomic selectivity, operative efficiency, and ultimately patient outcomes.

Neuronavigation-guided Percutaneous Rhizotomies to Trigeminal Neuralgia: A Systematic Review

OBJECTIVE

Neuronavigation improves intraoperative visualization of the cranial structures, which is valuable in percutaneous surgical treatments for patients with trigeminal neuralgia (TN) who are refractory to pharmacotherapy or reluctant to receive open surgery. The objective of this review was to evaluate the available neuronavigation-guided percutaneous surgical treatment modalities with cannulation of foramen ovale to TN, and their relative benefits and limitations.

METHODS

This review was conducted based on the PRISMA statement. An initial search was performed on electronic databases, followed by manual and reference searches. Study and patient characteristics, rhizotomy procedure and neuronavigation details, and treatment outcomes (initial pain relief and pain recurrence within 2 y, success rate of forman ovale cannulation, and complications) were evaluated. The risk of bias was assessed with a quality assessment based on the ROBINS-I tools.

RESULTS

Ten studies (491 operations, 403 participants) were analyzed. Three percutaneous trigeminal rhizotomy modalities identified were radiofrequency thermocoagulation rhizotomy (RFTR), percutaneous balloon compression, and glycerol rhizotomy. Intraoperative computed tomography and magnetic resonance imaging fusion-based RFTR had the highest initial pain relief rate of 97.0%. The success rate of foramen ovale cannulation ranged from 92.3% to 100% under neuronavigation. Facial hypoesthesia and masticatory muscle weakness were the most reported complications.

DISCUSSION

Neuronavigation-guided percutaneous trigeminal rhizotomies showed possible superior pain relief outcomes to that of conventional rhizotomies in TN, with the benefits of radiation reduction and lower complication development rates. The limitations of neuronavigation remain its high cost and limited availability. Higher-quality prospective studies and randomized clinical trials of neuronavigation-guided percutaneous trigeminal rhizotomy were lacking.

Evaluation of the effects of personalized 3D-printed jig plate-assisted puncture in trigeminal balloon compression

OBJECTIVE

Percutaneous microballoon compression (PMC) is a simple and effective surgical procedure for the treatment of trigeminal neuralgia. The difficulty with this surgery is related to accurate and quick foramen ovale puncture. In this study, we compared the application of personalized 3D-printed guides and the traditional puncture method in trigeminal PMC surgery.

METHOD

Data from 40 patients with primary trigeminal neuralgia treated with PMC between June 2017 and August 2019 were analyzed retrospectively. Personalized 3D-printed jigs were used to assist foramen ovale puncture in 20 patients, and Hartel positioning was used for puncture in 20 patients. Three-dimensional reconstruction was performed preoperatively using 3DSlicer software to understand the size of the foramen ovale and positioning of related anatomical structures. Based on the reconstruction, personalized surgical paths were created for the jig plate-assisted treatment group, and the printed jig plate was applied to the surgery through 3D printing to explore the surgical effect.

RESULTS

Foramen ovale puncture was successful in all patients. Better results were achieved with guides than with the traditional method in terms of the foramen ovale puncture time (p < 0.01), total operation time (p < 0.01), and number of computed tomography scans (p < 0.01). The efficacy of surgery and postoperative complications did not differ between groups (p = 1).

CONCLUSIONS

The use of personalized 3D-printed guides enables accurate puncture positioning in PMC, and improves the success rate of surgery, shortens the operation time, and reduces surgical risk, which has broad prospects in clinical application.

Anatomic Variations of Foramen Ovale as a Predictor of Successful Cannulation in Percutaneous Trigeminal Rhizotomies

BACKGROUND AND OBJECTIVES

Percutaneous trigeminal rhizotomies are common treatment modalities for medically refractory trigeminal neuralgia (TN). Failure of these procedures is frequently due to surgical inability to cannulate the foramen ovale (FO) and is thought to be due to variations in anatomy. The purpose of this study is to characterize the relationships between anatomic features surrounding FO and investigate the association between anatomic morphology and successful cannulation of FO in patients undergoing percutaneous trigeminal rhizotomy.

METHODS

A retrospective analysis was conducted of all patients undergoing percutaneous trigeminal rhizotomy for TN at our academic center between January 1, 2010, and July 31, 2022. Preoperative 1-mm thin-cut computed tomography head imaging was accessed to perform measurements surrounding the FO, including inlet width, outlet width, interforaminal distance (a representation of the lateral extent of FO along the middle fossa), and sella-sphenoid angle (a representation of the coronal slope of FO). Mann-Whitney U tests assessed the difference in measurements for patients who succeeded and failed cannulation.

RESULTS

Among 37 patients who met inclusion criteria, 34 (91.9%) successfully underwent cannulation. Successful cannulation was associated with larger inlet widths (median = 5.87 vs 3.67 mm, U = 6.0, P = .006), larger outlet widths (median = 7.13 vs 5.10 mm, U = 14.0, P = .040), and smaller sella-sphenoid angles (median = 52.00° vs 111.00°, U = 0.0, P < .001). Interforaminal distances were not associated with the ability to cannulate FO surgically.

CONCLUSION

We have identified morphological characteristics associated with successful cannulation in percutaneous rhizotomies for TN. Preoperative imaging may optimize surgical technique and predict cannulation failure.

New insight into the mandibular nerve at the foramen ovale level for percutaneous radiofrequency thermocoagulation

Background

Percutaneous radiofrequency thermocoagulation (RFTC) has been widely utilized in the management of trigeminal neuralgia. Despite using image guidance, accurate needle positioning into the target area still remains a critical element for achieving a successful outcome. This study was performed to precisely clarify the anatomical information required to ensure that the electrode tip is placed on the sensory component of the mandibular nerve (MN) at the foramen ovale (FO) level.

Methods

The study used 50 hemi-half heads from 26 South Korean adult cadavers.

Results

The cross-sectioned anterior and posterior divisions of the MN at the FO level could be distinguished based on an irregular boundary and color difference. The anterior division was clearly brighter than the posterior one. The anterior division of the MN at the FO level was located at the whole anterior (38.0%), anteromedial (6.0%), anterior center (8.0%), and anterolateral (22.0%) parts. The posterior division was often located at the whole posterior or posterolateral parts of the MN at the FO level. The anterior divisions covered the whole MN except for the medial half of the posterolateral part in the overwrapped images of the cross-sectional areas of the MN at the FO level. The cross-sectional areas of the anterior divisions were similar in males and females, whereas those of the posterior divisions were significantly larger in males (P = 0.004).

Conclusions

The obtained anatomical information is expected to help physicians reduce unwanted side effects after percutaneous RFTC within the FO for the MN.

Foramen lacerum impingement of trigeminal nerve root as a rodent model for trigeminal neuralgia

Trigeminal neuralgia (TN) is a classic neuralgic pain condition with distinct clinical characteristics. Modeling TN in rodents is challenging. Recently, we found that a foramen in the rodent skull base, the foramen lacerum, provides direct access to the trigeminal nerve root. Using this access, we developed a foramen lacerum impingement of trigeminal nerve root (FLIT) model and observed distinct pain-like behaviors in rodents, including paroxysmal asymmetric facial grimaces, head tilt when eating, avoidance of solid chow, and lack of wood chewing. The FLIT model recapitulated key clinical features of TN, including lancinating pain-like behavior and dental pain-like behavior. Importantly, when compared with a trigeminal neuropathic pain model (infraorbital nerve chronic constriction injury [IoN-CCI]), the FLIT model was associated with significantly higher numbers of c-Fos-positive cells in the primary somatosensory cortex (S1), unraveling robust cortical activation in the FLIT model. On intravital 2-photon calcium imaging, synchronized S1 neural dynamics were present in the FLIT but not the IoN-CCI model, revealing differential implication of cortical activation in different pain models. Taken together, our results indicate that FLIT is a clinically relevant rodent model of TN that could facilitate pain research and therapeutics development.

Puncture approaches and guidance techniques of radiofrequency thermocoagulation through foramen Ovale for primary trigeminal neuralgia: Systematic review and meta-analysis

Objective

Trigeminal neuralgia (TN) is one of the leading causes of facial pain and seriously affects patients' quality of life. Foramen ovale (FO) radiofrequency thermocoagulation is a classic approach for the treatment of TN that has failed pharmacological therapy. This study summarized the safety and efficacy of transforaminal radiofrequency thermocoagulation for TN by comparing puncture approaches or guidance techniques, thereby providing higher-quality clinical evidence.

Methods

Databases including PubMed, Embase, Cochrane Library, CNKI, and Wanfang were searched for relevant studies published before May 2022. Relevant data were extracted for analysis to compare methodological variables and clinical outcomes.

Results

This meta-analysis included 27 studies with a total of 1,897 patients. In terms of puncture approaches, FO had a significant advantage in reducing VAS at 12 months postoperatively (P = 0.019) and efficacy (P = 0.043). However, FO performed poorly on complications (P < 0.001), operation time (P < 0.001), and the number of needle adjustments (P < 0.001). Regarding the guidance techniques, the adjunctive use of guidance techniques could reduce patients' 6-month VAS (P < 0.001) and 12-month VAS (P < 0.001), improve the efficacy (P = 0.032), reduce recurrence rates (P = 0.001), shorten operation times (P < 0.001), decrease times of intraoperative fluoroscopy (P < 0.001), and improve the success of the first puncture (P < 0.001).

Conclusion

FO radiofrequency thermocoagulation has advantages in efficacy it can still better relieve the pain of patients 12 months postoperatively. However, FO has disadvantages in complications, recurrences, and operation time. The adjunctive use of guidance techniques has a positive effect on treatment efficacy and safety during FO radiofrequency thermocoagulation. However, the results still require large samples and high-quality randomized clinical trials to confirm.

Morphologic and Morphometric Measurements of the Foramen Ovale: Comparing Digitized Measurements Performed on Dried Human Crania With Computed Tomographic Imaging. An Observational Anatomic Study

The foramen ovale (FO) of the sphenoid bone is clinically important for the interventional treatment of trigeminal neuralgia. Percutaneous procedures applied to treat the chronic pain condition typically involve the cannulation of this oval-like foramen located at the base of the skull. Anatomic variations of the FO have been reported to contribute to difficulties in the cannulation of this structure. Computed tomography (CT) can help the surgeon improve the accuracy and safety of the intervention. However, even with navigation technology, unsuccessful cannulation of the FO has been reported. The aim of this observational anatomic study was to define morphometric and morphologic data of the FO and to investigate for potential differences between measurements taken on dried human crania and digitized measurements of the FO measured on CT images. One hundred eighteen FOs were evaluated. Twenty FOs underwent CT scanning. The mean length of the foramen was 7.41±1.3 mm on the left side and 7.57±1.07 mm on the right. The mean width of the foramen was 4.63±0.86 mm on the left side and 4.33±0.99 on the right. The mean area on the left side was 27.11±7.58 and 25.73±6.64 mm 2 on the right. No significant left-right differences were found for any of these dimensions. The most important conclusion that we can draw is that the measurements can indeed be performed on CT images to obtain an accurate picture of the morphology. Considering the surgical importance of the FO and taking into consideration the limitations this study added to scientific knowledge, this study was constructive as far as neurosurgeons and anatomists are concerned.

A review of literature and meta-analysis of one-puncture success rate in radiofrequency thermocoagulation with different guidance techniques for trigeminal neuralgia

OBJECTIVES

Radiofrequency thermocoagulation (RFT) is a type of Gasserian ganglion-level ablative intervention that is used for the treatment of trigeminal neuralgia. Guidance technologies are used to assist in the cannulation of the foramen ovale (FO) or foramen rotundum (FR) target. We conducted a systematic review to assess the value of different guidance technologies for RFT.

METHODS

We searched PubMed, Embase, the Cochrane database, Web of Science, and PROSPERO for studies published from January 2005 until December 2020. Randomized or nonrandomized comparative studies and nonrandomized studies without internal controls were included. The Cochrane Risk of Bias Tool and the nonrandomized studies of interventions-I tool were used to assess individual study characteristics and overall quality.

RESULTS

Our query identified 765 publications, and we were able to analyze 11 studies on patients suffering from trigeminal neuralgia. Only one study involved randomized controlled trials, whereas the others featured nonrandomized designs, predominantly before-and-after comparisons. Most of them were observational studies. A total of 222 participants were included, with a median number (range) of 20 (3-53) participants. The objective response rate (ORR) of the one-puncture success rate of RFT using puncture guidance for trigeminal neuralgia was 92% [95% CI (0.79-1), P < 0.001]. Statistically significant differences were observed in the cannulation and operation times between the guided and manual puncture groups (P < 0.001).

CONCLUSIONS

RFT with puncture guidance technology has an absolute advantage in puncturing the foramen ovale or foramen rotundum.

The impact of needle location on clinical outcome of radiofrequency rhizotomy for trigeminal neuralgia

BACKGROUND

Radiofrequency thermocoagulation trigeminal rhizotomy (RT-TR) through the foramen ovale is a minimally invasive treatment for trigeminal neuralgia. Navigation of magnetic resonance imaging (MRI) and CT fusion imaging is a well-established method for cannulation of the Gasserian ganglion. In this study, we use the inline measurements from fusion image to analyze the anatomical parameters between the actual and simulation trajectories and compare the short- and intermediate-term outcomes according to determinable factors.

METHODS

The study included thirty-six idiopathic neuralgia patients who had undergone RT-TR with MRI and CT fusion image as a primary modality or repeated procedures.

RESULTS

Among thirty-six treated patients, the inline length of the trigeminal cistern was longer for the simulated trajectory (8.4 ± 2.4 versus 6.5 ± 2.8 mm; p < 0.05), and the predominant structure at risk extrapolated from the inline trajectory was the brainstem, which signified a more medially directed route, in contrast with the equal weighting of temporal lobe and brainstem for the actual trajectory. The preoperative visual analogue scale (VAS) was 9.3 ± 1.0, which decreased to 2.5 ± 2.6 and 2.9 ± 3.1 at first (mean, 3 months) and second (mean, 14 months) postoperative follow-up, respectively. The postoperative VAS scores at the two follow-ups were not statistically significant without a covariate analysis. After adjustment for covariate risk factors, the second follow-up sustained therapeutic benefit was evident in patients with no prior history of related treatment, an ablation temperature greater than 70 °C, and needle location within or adjacent to the trigeminal cistern.

CONCLUSIONS

This preliminary study demonstrated that the needle location between cistern and ganglion also plays a significant role in better intermediate-term results.

Radiofrequency thermocoagulation for the treatment of trigeminal neuralgia

Although microvascular decompression (MVD) should be considered as the first-line treatment for classic trigeminal neuralgia (TN) owing to neurovascular compression of the trigeminal nerve, an increasing number of surgeons prefer radiofrequency thermocoagulation (RFT). RFT is a Gasserian ganglion-level ablative intervention that may achieve immediate pain relief for TN. It is used for emergency management when MVD is not suitable for the patient. As the gold surgical standard of classic trigeminal neuralgia, MVD has the advantage of longer efficacy. However, there are currently no high-quality controlled trials to evaluate the efficacy of MVD and RFT. For the present systematic review, the PubMed, Embase and Cochrane databases (all entries up until July 31, 2020) were searched to identify studies related to RFT in order to provide valuable information for clinical decision-making. The efficacy of the RFT method was evaluated in terms of the initial pain relief percentage, recurrence rate and follow-up time. Furthermore, the incidence rate of various postoperative complications was retrieved. RFT was used for a wider range of applications than MVD, including use for primary (owing to neurovascular compression of the trigeminal nerve), idiopathic and secondary (due to primary neurological diseases) TN, and provided a high rate of initial pain relief and long-term pain control. Although this method has several side effects, the incidence of complications could be reduced by precise cannulation. Furthermore, the complications that occurred were not permanent. Thus, RFT is a safe and effective minimally invasive method of pain relief for patients with TN.

Radiofrequency Ablation for Craniofacial Pain Syndromes

Headache disorders and trigeminal neuralgia are common conditions representing the types of craniofacial pain syndrome that can significantly impact quality of life. Many cases are refractory to traditional pharmacologic treatments, whether oral or intravenous. Radiofrequency ablation has been increasingly used as a tool to treat resistant, chronic pain of both of these disorders. Multiple studies have been reported that illustrate the efficacy of radiofrequency ablation in the treatment of the numerous headache subtypes and trigeminal neuralgia.

Frameless navigation-guided percutaneous rhizotomy of the trigeminal nerve: an appraisal of the literature

Percutaneous rhizotomy is a cornerstone of trigeminal neuralgia treatment. The procedure is classically performed under intermittent fluoroscopic guidance. While frameless navigation has been advanced to overcome potential difficulties and risks of the technique, literature on the subject is limited, and a gap between actual use and published series is likely. We have assessed all available studies of percutaneous rhizotomy of the trigeminal nerve performed under frameless navigation. Technical and clinical data that has been reviewed included clinical outcome, type of navigation employed, type of rhizotomy performed, types and rate of complications, operative time, cannulation time, and cannulation rate. Reports are heterogeneous, and most of these aspects have been inconsistently described. Comparisons with non-guided procedures are mostly indirect. While no obvious disadvantages are apparent when employing navigation, the ability to draw conclusions is nonetheless limited. Navigation appears as an inviting adjunct to trigeminal rhizotomy, but publication of longer, rigorously evaluated series would be welcomed.

Bipolar Pulsed Radiofrequency for Trigeminal Neuralgia: A Report of Two Cases

BACKGROUND

Trigeminal neuralgia (TN) is the most common cause of facial pain, leading to significant disability and impacting a patient's quality of life. Percutaneous procedures like continuous radiofrequency, pulsed radiofrequency (PRF), and combined continuous and pulsed radiofrequency have been studied in past years comparing different voltages in order to find more effective therapies with fewer complications (eg, numbness and masseter muscle weakness). With regard to young patients, there is still insufficient evidence on the most appropriate procedure in this patient population. PRF does not cause thermal damage. The mechanism of action involves delivering an electrical field to targeted nerves or tissues, modulating pain. We propose that bipolar pulsed radiofrequency (2 parallel cannulas) in the trigeminal ganglion produce a denser and larger field resulting in more effective controlled pain.

CASE PRESENTATION

We present 2 cases of 40- and 48-year-old men with severe V2 to V3 TN who underwent bipolar PRF. We performed bipolar PRF on the trigeminal ganglion through the foramen ovale using two 22-gauge 100-mm cannulas with 10-mm active tips. Parameters used were voltage of 85 V, pulse width of 20 milliseconds, and total duration time of 6 minutes. Both patients reported complete relief of pain after the procedure, and at 2-year follow-up they were pain free and experienced a better quality of life. No complications were reported.

CONCLUSION

Bipolar PRF could be a non-neurodestructive option for young people with TN and deserves further investigation as a treatment option.

Ossification of the pterygoalar and pterygospinous ligaments: a computed tomography analysis of infratemporal fossa anatomical variants relevant to percutaneous trigeminal rhizotomy

OBJECTIVE

Ossification of pterygoalar and pterygospinous ligaments traversing the superior aspect of the infratemporal fossa results in formation of osseous bars that can obstruct percutaneous needle access to the trigeminal ganglion through the foramen ovale (FO), interfere with lateral mandibular nerve block, and impede transzygomatic surgical approaches. Presence of these ligaments has been studied on dry skulls, but description of their radiological anatomy is scarce, in particular on cross-sectional imaging. The aim of this study was to describe visualization of pterygoalar and pterygospinous bars on computed tomography (CT) and to review their prevalence and clinical significance.

METHODS

The authors retrospectively reviewed 200 helical sinonasal CT scans by analyzing 0.75- to 1.0-mm axial images, maximum intensity projection (MIP) reconstructions, and volume rendered (VR) images, including views along the anticipated axis of the needle in percutaneous Hartel and submandibular approaches to the FO.

RESULTS

Ossified pterygoalar and pterygospinous ligaments were readily identifiable on CT scans. An ossified pterygoalar ligament was demonstrated in 10 patients, including 1 individual with bilateral complete ossification (0.5%), 4 patients with unilateral complete ossification (2.0%), and 5 with incomplete unilateral ossification (2.5%). Nearly all patients with pterygoalar bars were male (90%, p < 0.01). An ossified pterygospinous ligament was seen in 35 patients, including 2 individuals with bilateral complete (1.0%), 8 with unilateral complete (4%), 8 with bilateral incomplete (4.0%), 12 with bilateral incomplete (6.0%) ossification, and 5 (2.5%) with mixed ossification (complete on one side and incomplete on the contralateral side). All pterygoalar bars interfered with a hypothetical needle access to the FO using the Hartel approach but not the submandibular approach. In contrast, 54% of complete and 24% of incomplete pterygospinous bars impeded the submandibular approach to the FO, without affecting the Hartel approach.

CONCLUSIONS

This study provides the first detailed description of cross-sectional radiological and applied surgical anatomy of pterygoalar and pterygospinous bars. Our data are clinically useful during skull base imaging to predict potential obstacles to percutaneous cannulation of the FO and assist in the choice of approach, as these two variants differentially impede the Hartel and submandibular access routes. Our results can also be useful in planning surgical approaches to the skull base through the infratemporal fossa.

Treatment Outcomes in Trigeminal Neuralgia-A Systematic Review of Domains, Dimensions and Measures

BACKGROUND

Trigeminal neuralgia (TN) is a painful disorder characterized by sudden electric shock-like pain. It is a rare condition for which multiple treatments are available, including medical and surgical. The best treatment option is yet to be defined, and this is related to the lack of definition in the treatment outcomes and outcome measures. The aim of this systematic review was to summarize all the outcomes and outcomes measures that have been published to date and highlight variability in their use.

METHODS

We have conducted a literature search using a wide range of databases (1946-2019 for medical and 2008-2019 for surgical treatment), for all intervention studies in TN. Four hundred and sixty-seven studies were selected for data extraction on TN classification, data collection method, intervention, and treatment outcomes mapped to the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT guidelines).

RESULTS

Most studies collected data on pain (n = 459) and side effects (n = 386) domains; however, very few collected data on the impact of treatment on physical (n = 46) and emotional functioning (n = 17) and on patient satisfaction (n = 35). There was high variability on outcome measures used for pain relief (n = 10), pain intensity (n = 9), and frequency of pain episodes (n = 3).

CONCLUSIONS

A clear definition of what are the important outcomes for patients with TN is essential. The choice of standardized outcome measures allowing for consistent reporting in TN treatment will allow for comparison of studies and facilitate treatment choice for patients and clinicians thus, improving health outcomes and reducing health care cost.

The applicability and efficacy of magnetic resonance-guided high intensity focused ultrasound system in the treatment of primary trigeminal neuralgia

Primary trigeminal neuralgia is a common clinical refractory neuralgia characterized by an onset of excruciating pain that can severely affect patients' quality of life. Long-term suffering from this pain may lead to depression, anxiety, and suicide. Current treatments, however, are associated with high recurrent rates and severe complications. We hypothesize that both the applicability and efficacy of magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) treatment in primary trigeminal neuralgia can be achieved under the following conditions: a specific target focus and incident channel, a temperature measurement system that does not incur damage to surrounding tissues, and an optimal radiation dose. Successful non-invasive treatment of primary trigeminal neuralgia by MR-HIFU systems could represent a breakthrough of this technology applied to the oral and maxillofacial region.

A Retrospective Review of the Outcomes and Utility of Percutaneous Radiofrequency Rhizotomy for Trigeminal Neuralgia Using Anatomic Landmark Guidance in Asleep Patients

BACKGROUND

Radiofrequency rhizotomy is a percutaneous procedure for trigeminal neuralgia frequently performed with intermittent awakening, although the utility and accuracy of this procedure in continuously sedated patients have not yet been evaluated.

OBJECTIVE

To evaluate pain relief in patients with trigeminal neuralgia undergoing radiofrequency rhizotomy under continuous sedation.

METHODS

Patients from 2012 to 2017 who underwent radiofrequency rhizotomy for trigeminal neuralgia were evaluated retrospectively. Barrow Neurological Institute Pain Intensity scores were assigned to determine relapse at 1 mo, 1 yr, 3 yr, and 5 yr. Descriptive relapse rates for patients with multiple sclerosis and those undergoing repeat procedures are also reported.

RESULTS

A total of 90.8% of procedures reported Barrow Neurological Institute I-III score at 1 mo (P &lt; .0001), 66.3% at 1 yr (P = .0012), and 71.1% at 3 yr (P = .0003). Duration to relapse was 3.0 and 6.0 at 1 and 3 yr, respectively. Procedures in patients with multiple sclerosis reported 100% relief at 1 mo and 87.5% relief at 1 yr (P = .0099). The presence of numbness and postoperative medication changes were not associated with pain relief (P = .0063, P = .1338).

CONCLUSION

The use of continuous sedation in radiofrequency rhizotomy for trigeminal neuralgia provides pain relief comparable to the recorded literature rate for procedures with intermittent awakening.

Foramen ovale cannulation guided by intraoperative computed tomography with magnetic resonance image fusion plays a role in improving the long-term outcome of percutaneous radiofrequency trigeminal rhizotomy

Background

Percutaneous radiofrequency trigeminal rhizotomy (RF-TR) is a well-established treatment for patients suffering from trigeminal neuralgia (TN) as a primary modality or for those refractory to medical treatment. However, few existing studies have identified intraoperative parameter or navigation technique that can be used to predict the rates of short-term or long-term pain relief. In this study, we analyzed patient characteristics, intraoperative parameters and technical factors, and postoperative changes in relation to immediate and long-term pain relief.

Method

This study included a total 252 patients in which 340 RF-TR were performed under the guidance of intraoperative computed tomography (iCT) alone or with magnetic resonance image (MRI) and iCT fusion imaging.

Result

The immediate pain relief of RF-TR with iCT alone and iCT with MR image guidance with or without cerebrospinal fluid (CSF) outflow were all above 90.4%. The 2-year pain relief rate of RF-TR using iCT alone and iCT with MR images guidance with or without CSF outflow were 47.8%, 39.8%, 71.7%, and 53.9% respectively. Significant factors for 2-year pain relief were CSF outflow, iCT with MR image fusion, non-recurrent TN, and presence of postoperative facial numbness.

Conclusion

This preliminary study demonstrated foramen ovale cannulation under the aid of iCT with MR image guidance could improve 2-year pain relief.

Bipolar radiofrequency ablation of mandibular branch for refractory V3 trigeminal neuralgia

Background: Percutaneous trans-foramen ovale (FO) radiofrequency ablation (RFA) of Gasserian ganglion (GG) is commonly used to treat V3 trigeminal neuralgia (TN). However, this intracranial approach is less selective and safe.

Objectives: To report a novel percutaneous within-FO RFA of the V3 under CT-guidance and outcomes with both bipolar and monopolar techniques.

Patients and methods: Twenty-six patients with isolated V3 primary TN and FO >6 mm in diameter underwent either monopolar (n=12) or bipolar RFAs (n=14) based on their preference. Successful analgesia over V3, residual pain, recurrent pain, and complications were compared between the two groups. The ex vivo egg albumen model was used to demonstrate the size difference in the thermocoagulation lesion created by monopolar vs bipolar electrodes.

Results: In the bipolar group, there were more cases of masticatory atonia as compared to the monopolar (P=0.104), but no residual pain was observed. In the monopolar group, there were two cases of residual pain found, which led to immediate repeat RFAs. Therefore, during the immediate post-operative period, both groups obtained 100% complete V3 analgesia with a similar risk of facial hematoma (P=0.641). During up to 27-months of post-operative follow-up, in the bipolar group, complete pain relief persisted in all patients; in the monopolar group, 1 case of recurrent pain was found at 14 months. Ex vivo study demonstrated that, at 90 °C/90 seconds of RFA, the width of lesions is significantly larger by the 6-mm spacing parallel-tip bipolar electrodes compared to the monopolar electrode (9.5±0.567 vs 5.5±0.07 mm).

Conclusion: In treating patients with isolated V3 TN and FO >6mm in diameter, this percutaneously within-FO RFA of the V3 under CT guidance is both clinically practical and effective, while bipolar RFA is associated with a lower incidence of residual and recurrent pain likely due to larger lesion sizes.

CT-guided percutaneous radiofrequency thermocoagulation for glossopharyngeal neuralgia: A retrospective clinical study of 117 cases

OBJECTIVE

Glossopharyngeal neuralgia (GPN) is a rare disorder of the ninth cranial nerve. Percutaneous radiofrequency thermocoagulation (PRT) is an established treatment for neuropathic pain. Since PRT was first applied with GPN, only a few studies have provided detailed reports on its clinical outcomes and complications, and the number of cases was small. The aim of this study was to investigate the effects, incidence rates, and severity of adverse events of computed tomography (CT)-guided PRT in 117 patients with GPN.

PATIENTS AND METHODS

A total of 117 patients with idiopathic GPN underwent CT-guided PRT from July 2004 to December 2016. A retrospective review of medical records was performed to investigate baseline characteristics and immediate outcomes after operation. Long-term outcomes were obtained via telephone interviews. Patients were followed up at 3 months, 6 months, and thereafter, every year after operation. According to Barrow Neurological Institute (BNI) pain scale, the effects of this treatment were categorized into 5 levels. Adverse events, frequencies, severity, and recovery times of complications were recorded.

RESULTS

Patients who were classified into BNI class I and BNI class II experienced excellent pain relief. Ninety-six patients (82.1%) achieved "excellent" pain relief immediately after treatment. The mean follow-up period was 73.6 months (range, 13-150). With regard to long-term outcomes, the percentage of patients who experienced "excellent" pain relief was 75.9% at 1 year, 63.0% at 3 years, 54.0% at 5 years, 44.2% at 10 years, and 39.3% at 12.5 years. Complications, which included dysphagia, lingual numbness, pharynx and larynx numbness, hoarseness, and abnormal sense of taste, were graded 1 as defined by the Landriel Ibanez classification, and all complications disappeared within 12.9 ± 5.1 weeks.

CONCLUSION

This study indicates that PRT is a minimally invasive procedure that leads to minor complications and is proven to have immediate and long-term effectiveness for managing GPN. It is especially suitable for patients with contraindication to surgery and patients who require recurrent treatment. We provide a detailed report of the adverse events experienced by GPN patients who underwent PRT.

Electromagnetic neuronavigation for the percutaneous treatment of trigeminal neuralgia with balloon compression: technical note and cadaveric validation study

BACKGROUND

Several techniques have been described for the percutaneous treatment of trigeminal neuralgia; however, each has significant drawbacks. We propose a new technique for percutaneous balloon compression of the trigeminal ganglion and distal trigeminal nerve using electromagnetic (EM) neuronavigation.

METHODS

The procedure was performed in 17 consecutive patients with trigeminal neuralgia. Patients were then followed up with telephone interview. We also performed a cadaveric validation study to further investigate the accuracy of the technique using dye.

RESULTS

Excellent clinical outcomes were achieved with a reduction in the median pain score from 10 out of 10 to 0 out of 10 following the procedure. The cadaveric study also demonstrated a high rate of foramen ovale cannulation.

CONCLUSION

EM-based targeting of the foramen ovale and balloon inflation within Meckel's cave is a quick, reproducible and straightforward technique for the percutaneous treatment of trigeminal neuralgia.