A review of percutaneous treatments for trigeminal neuralgia

A Comprehensive Narrative Review of Neuropathic Pain: From Pathophysiology to Surgical Treatment

Neuropathic pain is a challenging condition. Despite the immense progress made in the pathophysiology and treatment of such conditions, so much work still has to be done. New frontiers previously unexplored are now objects of study with exciting results, mainly regarding neuromodulation and optogenetics. This review explores the already known pathophysiology and the clinical and surgical treatment in the light of evidence-based medicine. Additionally, new concepts and insights are discussed, presenting the hope for the development of new paradigms in the treatment of neuropathic pain.

A nomogram based on radiomics and clinical information to predict prognosis in percutaneous balloon compression for the treatment of trigeminal neuralgia

OBJECTIVE

To develop a clinical-radiomics nomogram based on clinical information and radiomics features to predict the prognosis of percutaneous balloon compression (PBC) for the treatment of trigeminal neuralgia (TN).

METHODS

The retrospective study involved clinical data from 149 TN patients undergoing PBC at Zhongnan Hospital, Wuhan University from January 2018 to January 2022. The free open-source software 3D Slicer was used to extract all radiomic features from the intraoperative X-ray balloon region. The relationship between clinical information and TN prognosis was analyzed by univariate logistic analysis and multivariate logistic analysis. Using R software, the optimal radiomics features were selected using the least absolute shrinkage and selection operator (Lasso) algorithm. A prediction model was constructed based on the clinical information and radiomic features, and a nomogram was visualized. The performance of the clinical radiomics nomogram in predicting the prognosis of PBC in TN treatment was evaluated using the area under the receiver operating characteristic curve (AUC) and decision curve analysis (DCA).

RESULTS

A total of 149 patients were eventually included. The clinical factors influencing the prognosis of TN in univariate analysis were compression severity score and TN type. The lasso algorithm Max-Relevance and Min-Redundancy(mRMR) was used to select two predictors from 13 morphology-related radiomics features, including elongation and surface-volume ratio. A total of 4 predictors were used to construct a prediction model and nomogram. The AUC was 0.886(95% confidence interval (CI), 0.75 to 0.96), indicating that the model's good predictive ability. DCA demonstrated the nomogram's high clinical applicability.

CONCLUSION

Clinical-radiomics nomogram constructed by combining clinical information and morphology-related radiomics features have good potential in predicting the prognosis of TN for PBC treatment. However, this needs to be further studied and validated in several independent external patient populations.

Clival-Meckel's Cave Angle: A Predictor of Glycerol Displacement in Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia

BACKGROUND AND OBJECTIVES

Percutaneous glycerol rhizotomy successfully treats trigeminal neuralgia although failure rates and durability of the procedure are variable. Some of this variability in clinical outcome might be due to egress of glycerol from Meckel's cave (MC) because of surgical positioning and individual patient anatomy. In this article, we quantitatively analyzed the anatomic variances that affect glycerol fluid dynamics to better predict patients more amenable for percutaneous glycerol injections.

METHODS

Computed tomography imaging of 11 cadaveric heads was used to calculate bilateral Clival-Meckel's cave (CMC) and sella-temporal (ST) angles. Twenty-two cadaveric percutaneous injections of dyed glycerol into the Meckel's cave were performed using Härtel's approach, and the fluid movement was documented at prespecified intervals over 1 hour. The relationship between the angles and glycerol migration was studied.

RESULTS

Specimens with basal cistern involvement by 60 minutes had significantly greater CMC angles (median [IQR]: basal cistern involvement = 74.5° [59.5°-89.5°] vs no basal cistern involvement = 58.0° [49.0°-67.0°]), U = 6.0, P < .001. This model may predict which patients will experience glycerol migration away from the Gasserian ganglion (area under the curve: 0.950, SE: 0.046, CI: 0.859-1.041, P < .001). Increased ST angle was associated with lateral flow of glycerol (r s = 0.639, P = .001), and CMC angle was associated with total area of dispersion (r s = -0.474, P = .026).

CONCLUSION

Anatomic variation in skull base angles affects glycerol migration. Specifically, a more obtuse CMC angle was associated with a higher risk of posterior migration away from the Gasserian ganglion. This may be a reason for differing rates of surgical success. These results suggest that anterior head flexion for 60 minutes may prevent percutaneous glycerol rhizotomy failures and some patients with large CMC angles are more likely to benefit from postinjection head positioning. However, this clinical effect needs validation in vivo.

Review of craniofacial pain syndromes involving the greater occipital nerve: relevant anatomy, clinical findings, and interventional management

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.

Percutaneous ballon compression for recurrent TN -a retrospective study of 33 cases

Objective

To investigate the clinical efficacy of percutaneous microballoon compression in the treatment of recurrent TN.

Methods

This retrospective study included 33 patients who underwent percutaneous microballoon compression for the treatment of recurrent TN from March 2019 to May 2022. Postoperative pain recurrence and facial numbness were assessed according to the Barrow Neurological Institute (BNI) pain score. Patients' anxiety and sleep status during follow-up were assessed according to the Self-rating Anxiety Scale (SAS) and Pittsburgh Sleep Quality Index (PSQI).

Results

All patients (33 cases) were followed up for 12-38 months, with an average follow-up time of 23 months. On postoperative day 1, 31 patients (93.9%) reported no pain, and 2 patients were given drug treatment for pain relief, The total efficacy was 93.9%. Moreover, 2 patients (6.1%) reported significant pain relief 2 weeks postoperatively. There are many complications during and after PBC. The incidence of the trigeminocardiac reflex (TCR) during surgery was 100%, and the incidence of facial numbness, masseter muscle weakness, labial herpes and headache was 97, 60.6, 12.1 and 3%. No patient experienced severe facial numbness, hearing impairment, diplopia, injury to cranial nerves, Meningitis, intracranial haemorrhage or keratitis. 1 patient had recurrence of pain at 6 months post-op, which was relieved by oral medication. 81.8% suffered from anxiety and 54.5% had poor sleep quality before surgery. After the period of PBC, SAS and PSQI scores decreased continuously. There were significant improvements in anxiety and sleep status postoperatively compared with preoperatively.

Conclusion

PBC is a safe and effective option for the treatment of recurrent TN. The arduous and demanding nature of the clinical course subjects the patient to severe pain, mental, and physical stress. Thankfully, it significantly improves the symptoms of anxiety, depression, and sleep quality.

Proximal trigeminal nerve atrophy is associated with favourable outcomes and persistent facial numbness following percutaneous balloon compression for primary trigeminal neuralgia

OBJECTIVE

Whether nerve atrophy can affect the prognosis of primary trigeminal neuralgia (PTN) patients undergoing percutaneous balloon compression (PBC) remains unclear. This study aimed to determine the association between nerve characteristics observed on preoperative magnetic resonance imaging (MRI) and PBC outcomes.

METHODS

Between January 2019 and December 2022, a cohort of 58 patients with unilateral PTN treated with PBC were analysed retrospectively and included in this study. The relationship between MRI findings, including the proximal and distal nerve cross-sectional areas (CSAs), and favourable pain outcomes (BNI Grades I-III) was analysed through Kaplan‒Meier analysis.

RESULTS

After a mean follow-up period of 23.8 ± 13.0 months (range, 6-50 months), 48 (82.8%) patients with PTN were pain free with or without medication. A smaller proximal CSA ratio (proximal CSA of the affected nerve/proximal CSA of the unaffected nerve) was significantly associated with favourable outcomes. The Kaplan-Meier survival analysis showed that patients with proximal nerve atrophy (proximal CSA ratio ≤ 87% after receiver operating characteristic curve analysis) had a higher estimated 4-year probability of maintaining a favourable outcome than those without nerve atrophy (94.4% vs. 30.8%, p = 0.005). In addition, patients with proximal nerve atrophy were more likely to suffer from postoperative persistent facial numbness.

CONCLUSIONS

Proximal nerve atrophy is correlated with both favourable outcomes and persistent facial numbness following PBC. Prospective studies are required to determine the optimal duration and pressure of balloon compression in relation to the proximal CSA ratio to achieve better pain outcomes and less facial numbness.

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.

Modification to the Hartel Route Radiofrequency Technique for the Treatment of Trigeminal Neuralgia: A Technical Note

OBJECTIVE

To evaluate a modification to the classical Hartel technique for the treatment of trigeminal neuralgia.

METHODS

Intraoperative radiographs of 30 patients with trigeminal neuralgia treated with radiofrequency were retrospectively reviewed. The distance between the needle and the anterior edge of the temporomandibular joint (TMJ) was measured on strict lateral skull radiographs. Surgical time was reviewed, and clinical outcomes were evaluated.

RESULTS

All patients showed clinical improvement in pain (Visual Analog Scale). In all radiographs, the measurement between the needle and the anterior edge of the TMJ ranged from 10 mm to 22 mm. None of the measurements were below 10 mm or above 22 mm. In most cases, this distance was 18 mm (9 patients), followed by 16 mm in 5 patients.

CONCLUSIONS

Considering the inclusion of the oval foramen in a Cartesian coordinate system with axes X, Y, and Z is useful. Directing the needle to a point located 1 cm from the anterior edge of the TMJ, avoiding the medial aspect of the upper jaw ridge, allows for a safer and faster procedure.

The Consistency Between the Preoperative 3D-Reconstructed Meckel's Cave and the Intraoperative Balloon Results in Percutaneous Balloon Compression

Objective

To predict the volume and shape of the balloon before PBC by reconstructing the Meckel's cave (MC) and establishing a volumetric measurement model, supporting preoperative preparation and intraoperative decisions.

Methods

The clinical data of 31 patients with good therapeutic effects who underwent PBC are retrospectively collected, including preoperative MRI, the volume of contrast agent injected into the balloon, and intraoperative lateral X-ray images. The MC on the affected side of the 31 patients is reconstructed based on MRI using 3D Slicer, while the volume of the MC is calculated to compare with the volume of contrast agent. The width (W) and length (L) of the model of the MC in lateral view are measured and used to classify the shape of the MC based on W/L. The consistency between the W/L of the model of the MC and the W/L of the intraoperative balloon is evaluated.

Results

For volume, the mean value of the models of the MC (V1) in 31 patients is 399.77±155.13 mm³, while the mean value of the contrast agent injected during PBC (V2) is 539.03±111.93 mm³. The formula obtained by linear regression is V2= 392.1 + 0.3676×V1. Based on the value of W/L, the shape of the MC is classified into thin "pear" in 5 patients (16.13%), standard "pear" in 22 patients (70.97%), and square "pear" in 4 patients (12.90%). There is no significant difference in W/L between the models of the MC and the intraoperative balloons in 31 patients (P=0.221).

Conclusion

In 31 patients with good efficacy, it is verified that the prediction of the MC before PBC by 3D Slicer is consistent with the actual situation of the intraoperative balloon. This method can provide certain basis for preoperative preparation and intraoperative judgment.

Percutaneous Rhizotomy of the Gasserian Ganglion in Patients With Mass Lesion-Associated Trigeminal Neuralgia: A Case Series

BACKGROUND

Patients with trigeminal neuralgia (TN) secondary to mass lesions are typically treated by directly addressing the underlying pathology. In cases of TN not alleviated by treatment of the pathology, percutaneous balloon compression (PBC) and glycerol rhizotomy (Gly) are simple and effective ways to alleviate pain. However, there is limited literature on the use of these techniques for patients with TN caused by mass lesions.

OBJECTIVE

To describe the use of PBC/Gly to treat mass lesion-related TN.

METHODS

We report a retrospective, single-institution, descriptive case series of patients who presented with TN secondary to tumor or mass-like inflammatory lesion from 1999 to 2021. Patients with primary, idiopathic, or multiple sclerosis-related TN were excluded. Outcomes included Barrow Neurological Institute (BNI) pain intensity and hypesthesia scores, pain persistence, and postoperative complications.

RESULTS

A total of 459 procedures were identified, of which 16 patients met the inclusion criterion (14 PBC and 2 Gly). Of the 15 patients with tumors, 12 had TN pain despite prior tumor-targeted radiation. Short-term (<3 months) BNI pain intensity improvement occurred in 15 (93.8%) patients. The mean follow-up was 54.4 months. Thirteen (81.3%) patients were pain-free (Barrow Neurological Institute pain intensity scale: IIIa-50%; I-25.0%; II-6.3%) for a mean of 23.8 (range 1-137) months. Ten patients (62.5%) had pain relief for ≥6 months from first procedure. New facial numbness developed immediately postprocedure in 8 (50%) patients. Transient, partial abducens nerve palsy occurred in 1 patient.

CONCLUSION

PBC/Gly is an effective option for medically refractory TN in patients with mass-associated TN and is a viable option for repeat treatment.

Retrospective comparison of percutaneous balloon compression and radiofrequency-thermocoagulation in the management of trigeminal neuralgia

PURPOSE

To compare percutaneous balloon compression (PBC) and radiofrequency thermocoagulation (RFTC) for the treatment of trigeminal neuralgia.

METHODS

This was a retrospective single-center analysis of data from 230 patients with trigeminal neuralgia who underwent 202 PBC (46%) and 234 RFTC (54%) from 2002 to 2019. Comparison of demographic data and trigeminal neuralgia characteristics between procedures as well as assessment of 1) initial pain relief by an improved Barrow Neurological Institute (BNI) pain intensity scale of I-III; 2) recurrence-free survival of patients with a follow-up of at least 6 months by Kaplan-Meier analysis; 3) risk factors for failed initial pain relief and recurrence-free survival by regression analysis; and 4) complications and adverse events.

RESULTS

Initial pain relief was achieved in 353 (84.2%) procedures and showed no significant difference between PBC (83.7%) and RFTC (84.9%). Patients who suffered from multiple sclerosis (odds ratio 5.34) or had a higher preoperative BNI (odds ratio 2.01) showed a higher risk of not becoming pain free. Recurrence-free survival in 283 procedures was longer for PBC (44%) with 481 days compared to RFTC (56%) with 421 days (p=0.036) but without statistical significance. The only factors that showed a significant influence on longer recurrence-free survival rates were a postoperative BNI ≤ II (P=<0.0001) and a BNI facial numbness score ≥ 3 (p = 0.009). The complication rate of 22.2% as well as zero mortality showed no difference between the two procedures (p=0.162).

CONCLUSION

Both percutaneous interventions led to a comparable initial pain relief and recurrence-free survival with a low and comparable probability of complications. An individualized approach, considering the advantages and disadvantages of each intervention, should guide the decision-making process. Prospective comparative trials are urgently needed.

Augmented Reality-Assisted Percutaneous Rhizotomy for Trigeminal Neuralgia

BACKGROUND

Percutaneous rhizotomy of the trigeminal nerve is a common surgery to manage medically refractory trigeminal neuralgia. Traditionally, these procedures have been performed based on anatomic landmarks with fluoroscopic guidance. Augmented reality (AR) relays virtual content on the real world and has the potential to improve localization of surgical targets based on preoperative imaging.

OBJECTIVE

To study the potential application and benefits of AR as an adjunct to traditional fluoroscopy-guided glycerol rhizotomy (GR).

METHODS

We used traditional fluoroscopy-guided percutaneous GR technique as previously described, performed under general anesthesia. Anatomic registration to the Medivis SurgicalAR system was performed based on the patient's preoperative computerized tomography, and the surgeon was equipped with the system's AR goggles. AR was used as an adjunct to fluoroscopy for trajectory planning to place a spinal needle into the medial aspect of the foramen ovale.

RESULTS

A 50-year-old woman with multiple sclerosis-related right-sided classical trigeminal neuralgia had persistent pain, refractory to medications, previous gamma knife stereotactic radiosurgery, and percutaneous radiofrequency rhizotomy performed elsewhere. The patient underwent AR-assisted fluoroscopy-guided percutaneous GR. The needle was placed into the right trigeminal cistern within seconds. She was discharged home after a few hours of observation with no complications and reported pain relief.

CONCLUSION

AR-assisted percutaneous rhizotomy may enhance the learning curve of these types of procedures and decrease surgery duration and radiation exposure. This allowed rapid and correct placement of a spinal needle through the foramen ovale.

The Key to a Successful PBC in Treatment of Trigeminal Neuralgia

As a minimally invasive treatment of trigeminal neuralgia, percutaneous balloon compression (PBC) has become increasingly popular worldwide. Because it is simple and straightforward, it does not need a complicated apparatus only a fluoroscope plus an operator's experience. Therefore, the surgical technique seems to be essential and worth further addressing. The paper stresses that the target of PBC should be the semilunar ganglion (the soma of neurons) rather than the rootlets (axons) because the latter is renewable. To obtain a sufficient pressure against the ganglion, Meckel's cave should be covered utterly by an inflating balloon, which fluoroscopically appears in a pear shape. To attain a proper balloon position, it is suggested to make a tunnel with a blunt stylet in a proper penetrative angle before inserting a soft catheter. Too large a pear is unnecessary, hence injecting should be stopped when growth becomes apparently slow. To avoid an unacceptable postoperative paresthesia, a prolonged compression is not encouraged.

Percutaneous balloon compression for secondary trigeminal neuralgia caused by cerebellopontine angle tumors

OBJECTIVE

The most common cause for trigeminal neuralgia (TN) is vascular compression at the nerve root, and microvascular decompression (MVD) has been proven to be an effective surgical approach for this disease. For some patients, TN is secondary to the intracranial space-occupying lesion, and tumor resection is usually recommended. However, it is not easy to determine proper treatments when craniotomy is infeasible. In this study, we aim to explore the clinical outcomes of percutaneous balloon compression (PBC) for secondary TN caused by cerebellopontine angle (CPA) tumors.

METHODS

From June 2016 to December 2019, 15 patients with TN caused by CPA tumors underwent PBC in Nanjing Drum Tower Hospital. The clinical features, surgical outcomes, and complications of these patients were analyzed retrospectively.

RESULTS

Fourteen out of the 15 patients had immediate pain relief after successful PBC, while one showed occasional pain, without needing any medication. No patients had a relapse of facial pain within a mean follow-up of 32.5 months. As for surgical complications, 14 patients experienced facial numbness, and six had masseter muscle weakness. No patients experienced serious surgical morbidities.

CONCLUSIONS

For the patients with TN caused by CPA tumors, PBC could be considered a useful technique, especially when craniotomy is infeasible.

The Focus and New Progress of Percutaneous Balloon Compression for the Treatment of Trigeminal Neuralgia

Trigeminal neuralgia is a condition confined to the trigeminal nerve, causing one or more branches of facial nerve pain. Surgical treatment options for trigeminal neuralgia include microvascular decompression(MVD), percutaneous balloon compression (PBC), radiofrequency thermocoagulation(RF), percutaneous retrogasserian glycerol rhizotomy(PRGR), gamma knife, etc. Of these treatments, PBC is increasingly being used by clinicians for trigeminal neuralgia. PBC is a simple surgical operation performed to treat trigeminal neuralgia. Owing to its advantages, PBC is favored by many clinicians. In this study, we aimed to emphasize the need to analyze the shape of the balloon, position, compression time, and pressure, as these factors can affect the efficacy of PBC. The relief of pain by balloon compression is related to the shape of the balloon on X-ray, which is the key to the operation. Owing to continued progress and advances in current imaging technologies, clinicians revealed that the precise positioning of the foramen ovale is no longer an intraoperative problem. Instead, the anatomy of Meckel’s cave and the shape of the balloon must be the focus to achieve the best treatment effect. For clinicians, PBC is simple and is associated with a short operation time. PBC also has other advantages, such as low cost and immediate postoperative pain relief. The recurrence rate of pain post-PBC is low, despite the occurrence of facial numbness post-op. However, this side effect is reversible and does not affect daily life of the patient. In fact, the patient can be discharged 1–2 days after surgery. Overall, PBC can be considered as one of the preferred surgical methods for the treatment of primary trigeminal neuralgia. In this paper, we explain the main points of PBC operation in detail in terms of Meckel’s cave, surgical procedure, complications, discussion of the focus and new progress, etc.

Radiofrequency thermoablation of the peripheral branches of trigeminal nerve versus the Gasserian ganglion for treating idiopathic trigeminal neuralgia: A systematic review and meta-analysis

BACKGROUND

Trigeminal neuralgia is characterized by pain at the distribution of one or more of the trigeminal nerve branches and is usually treated with anti-epileptic medication. When first line treatment fails, patients receive other treatment modalities including radiofrequency thermoablation (RFT) of the Gasserian ganglion and peripheral branches of the trigeminal nerve. The aim of this study is to compare RFT of the Gasserian ganglion and peripheral branches of trigeminal nerve in terms of efficacy and rate of complications.

METHODS

This was a systematic review and meta-analysis that searched Medline, Cochrane Central Register of Controlled Trials, and Embase using Medical Subject Headings and the references of the enrolled studies with no restriction on date. We included only RCTs that compared the RFT of the Gasserian ganglion and peripheral branches of trigeminal nerve with one of the following outcomes: pain scales, immediate effective rate, recurrence rate, and complications.

RESULTS

Five articles were eligible for our review and showed that there was no difference between RFT of the peripheral nerves and the Gasserian ganglion in terms of pain scores. There was a non-significant trend for RFT of the peripheral nerve to have higher immediate effect rates and higher recurrence rates. RFT of the Gasserian ganglion group was associated with masticatory weakness, while the other group was associated with facial swelling and numbness of V2.

CONCLUSION

RFT of the peripheral branches is a safe and effective method to treat idiopathic trigeminal neuralgia but leads to a higher recurrence rate when compared with RFT of the Gasserian ganglion.

Percutaneous Procedures for Trigeminal Neuralgia

Microvascular decompression is the gold standard for the treatment of trigeminal neuralgia (TN). However, percutaneous techniques still play a role in treating patients with TN and offer several important advantages and efficiency in obtaining immediate pain relief, which is also durable in a less invasive and safe manner. Patients' preference for a less invasive method can influence the procedure they will undergo. Neurovascular conflict is not always a prerequisite for patients with TN. In addition, recurrence and failure of the previous procedure can influence the decision to follow the treatment. Therefore, indications for percutaneous procedures for TN persist when patients experience idiopathic and episodic sharp shooting pain. In this review, we provide an overview of percutaneous procedures for TN and its outcome and complication.

Treatment of Third Branch Trigeminal Neuralgia With a Balloon Inflated in the Foramen Ovale

Objective

To investigate the efficacy of modified percutaneous balloon compression for simple third branch pain and its postoperative complications.

Methods

Clinical data and surgical records of 132 patients with third branch pain treated with percutaneous balloon compression from March 2015 to May 2019 were retrospectively analyzed, of which 81 cases were in the modified group and 51 cases were in the classic group. The modified technique was to compress again at the foramen ovale to enhance the compression in V3 after compression of the Gasserian ganglion.

Results

In the modified group, the overall therapeutic efficiency was 96.3%, with 77 patients (95.1%) having immediate postoperative pain relief and one patient (1.2%) having occasional pain without the need for medication. In the classic group, immediate postoperative pain relief was seen in 43 cases (84.3%), and two patients (3.9%) had occasional pain with no need for medication. The rate of complete pain relief was significantly higher in the modified group than in the classic group (P < 0.05). Postoperative follow-up ranged from 14 to 48 months. The pain-free rates were 77.8 and 54.9% in the modified and classic groups, respectively. The incidence of facial numbness in the region of the first branch was significantly lower than in the classic group (P < 0.001).

Conclusion

The modified procedure has significant advantages over the classic procedure in improving surgical efficacy, reducing postoperative recurrence rate, and decreasing postoperative numbness in the region, and can be used to treat simple trigeminal neuralgia in the third branch.

Chinese expert consensus on minimally invasive interventional treatment of trigeminal neuralgia

BACKGROUND AND PURPOSE

Trigeminal neuralgia is a common condition that is associated with severe pain, which seriously affects the quality of life of patients. When the efficacy of drugs is not satisfactory or adverse drug reactions cannot be tolerated, minimally invasive interventional therapy has become an important treatment because of its simple operation, low risk, high repeatability and low cost. In recent years, minimally invasive interventional treatments, such as radiofrequency thermocoagulation (RF) of the trigeminal nerve and percutaneous microcompression (PMC), have been widely used in the clinic to relieve severe pain in many patients, however, some related problems remain to be addressed. The Pain Association of the Chinese Medical Association organizes and compiles the consensus of Chinese experts to standardize the development of minimally invasive interventional treatment of trigeminal neuralgia to provide a basis for its clinical promotion and application.

MATERIALS AND METHODS

The Pain Association of the Chinese Medical Association organizes the Chinese experts to compile a consensus. With reference to the evidence-based medicine (OCEBM) system and the actual situation of the profession, the Consensus Development Committee adopts the nominal group method to adjust the recommended level.

RESULTS

Precise imaging positioning and guidance are the keys to ensuring the efficacy and safety of the procedures. RF and PMC are the most widely performed and effective treatments among minimally invasive interventional treatments for trigeminal neuralgia.

CONCLUSIONS

The pain degree of trigeminal neuralgia is severe, and a variety of minimally invasive intervention methods can effectively improve symptoms. Radiofrequency and percutaneous microcompression may be the first choice for minimally invasive interventional therapy.

Automated Segmentation of Trigeminal Nerve and Cerebrovasculature in MR-Angiography Images by Deep Learning

Trigeminal neuralgia caused by paroxysmal and severe pain in the distribution of the trigeminal nerve is a rare chronic pain disorder. It is generally accepted that compression of the trigeminal root entry zone by vascular structures is the major cause of primary trigeminal neuralgia, and vascular decompression is the prior choice in neurosurgical treatment. Therefore, accurate preoperative modeling/segmentation/visualization of trigeminal nerve and its surrounding cerebrovascular is important to surgical planning. In this paper, we propose an automated method to segment trigeminal nerve and its surrounding cerebrovascular in the root entry zone, and to further reconstruct and visual these anatomical structures in three-dimensional (3D) Magnetic Resonance Angiography (MRA). The proposed method contains a two-stage neural network. Firstly, a preliminary confidence map of different anatomical structures is produced by a coarse segmentation stage. Secondly, a refinement segmentation stage is proposed to refine and optimize the coarse segmentation map. To model the spatial and morphological relationship between trigeminal nerve and cerebrovascular structures, the proposed network detects the trigeminal nerve, cerebrovasculature, and brainstem simultaneously. The method has been evaluated on a dataset including 50 MRA volumes, and the experimental results show the state-of-the-art performance of the proposed method with an average Dice similarity coefficient, Hausdorff distance, and average surface distance error of 0.8645, 0.2414, and 0.4296 on multi-tissue segmentation, respectively.

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.

A Segmentation Method of Foramen Ovale Based on Multiatlas

Trigeminal neuralgia is a neurological disease. It is often treated by puncturing the trigeminal nerve through the skin and the oval foramen of the skull to selectively destroy the pain nerve. The process of puncture operation is difficult because the morphology of the foramen ovale in the skull base is varied and the surrounding anatomical structure is complex. Computer-aided puncture guidance technology is extremely valuable for the treatment of trigeminal neuralgia. Computer-aided guidance can help doctors determine the puncture target by accurately locating the foramen ovale in the skull base. Foramen ovale segmentation is a prerequisite for locating but is a tedious and error-prone task if done manually. In this paper, we present an image segmentation solution based on the multiatlas method that automatically segments the foramen ovale. We developed a data set of 30 CT scans containing 20 foramen ovale atlas and 10 CT scans for testing. Our approach can perform foramen ovale segmentation in puncture operation scenarios based solely on limited data. We propose to utilize this method as an enabler in clinical work.

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.

Efficacy and safety of radiofrequency in the treatment of trigeminal neuralgia: a systematic review and meta-analysis

To assess the effectiveness of radiofrequency (RF) versus other percutaneous strategies (balloon compression, glycerol rhizotomy [GR], and microvascular decompression [MVD]) in patients with trigeminal neuralgia. We systematically searched the electronic databases of PubMed, Embase, and the Cochrane Library to identify eligible studies throughout October 2020. The odds ratio (OR) with 95% confidence interval (CI) was applied to assess effect estimates using the random-effects model. Eighteen retrospective cohort studies that enrolled 6391 patients with trigeminal neuralgia were included. We noted that RF was associated with an increased incidence of immediate pain relief compared with GR (OR 2.65; 95% CI 1.29-5.44; P = 0.008). Moreover, RF was associated with an increased risk of pain recurrence compared with MVD (OR 3.80; 95% CI 2.00-7.20; P < 0.001). Furthermore, RF was associated with an increased incidence of postoperative anesthesia compared with GR (OR 3.01; 95% CI 1.11-8.13; P = 0.030) or MVD (OR 4.62; 95% CI 2.15-9.93; P < 0.001). This study found that RF was superior to GR for the improvement in immediate pain relief; whereas, RF yielded an excess risk of pain recurrence compared with MVD. Moreover, the incidence of postoperative anesthesia in patients treated with RF significantly increased compared with the incidence after treatment with GR and MVD.

Microvascular Decompression Surgery for Elderly Patients: A Study Based on Proposals from the Joint Committee of the Japan Gerontological Society and the Japan Geriatrics Society

The present study evaluated the indications for microvascular decompression (MVD) in elderly patients based on the new classification of the elderly population proposed by the joint committee of the Japan Gerontological Society and the Japan Geriatrics Society in 2017.

Retrospective analysis of 171 patients with hemifacial spasm (HFS), trigeminal neuralgia (TN), and glossopharyngeal neuralgia (GPN) who underwent MVD in 2018. Patients were divided into three groups based on the proposal: old group, 75–89 years; pre-old group, 65–74 years; and not-old group, 64 years or younger. Preoperative comorbidities were divided into five types and the American Society of Anesthesiologists Physical Status (ASA-PS) was recorded. Outcome of the surgery and neurological complications were evaluated in June 2019.

No decrease in activity of daily living occurred in any patient and surgical results showed no difference among the three groups. Rate of preoperative cardiovascular diseases was higher in both the pre-old and old groups compared with the not-old group (p <0.001 and Cramer V = 0.429). In terms of ASA-PS classification, only ASA-PS I and II were found, and rate of ASA-PS II was higher in the pre-old and old groups compared with the not-old group (p <0.001 and Cramer V = 0.407). Some patients suffered from elevated blood pressure after surgery, but were successfully managed.

In conclusion, MVD for elderly patients can be achieved safely with careful patient selection and perioperative management. Data should be continuously accumulated for the future development of decision-making algorithm for MVD in the elderly.

Accuracy study of a binocular-stereo-vision-based navigation robot for minimally invasive interventional procedures

BACKGROUND

Medical robot is a promising surgical tool, but no specific one has been designed for interventional treatment of chronic pain. We developed a computed tomography-image based navigation robot using a new registration method with binocular vision. This kind of robot is appropriate for minimal invasive interventional procedures and easy to operate. The feasibility, accuracy and stability of this new robot need to be tested.

AIM

To assess quantitatively the feasibility, accuracy and stability of the binocular-stereo-vision-based navigation robot for minimally invasive interventional procedures.

METHODS

A box model was designed for assessing the accuracy for targets at different distances. Nine (three sets) lead spheres were embedded in the model as puncture goals. The entry-to-target distances were set 50 mm (short-distance), 100 mm (medium-distance) and 150 mm (long-distance). Puncture procedure was repeated three times for each goal. The Euclidian error of each puncture was calculated and statistically analyzed. Three head phantoms were used to explore the clinical feasibility and stability. Three independent operators conducted foramen ovale placement on head phantoms (both sides) by freehand or under the guidance of robot (18 punctures with each method). The operation time, adjustment time and one-time success rate were recorded, and the two guidance methods were compared.

RESULTS

On the box model, the mean puncture errors of navigation robot were 1.7 ± 0.9 mm for the short-distance target, 2.4 ± 1.0 mm for the moderate target and 4.4 ± 1.4 mm for the long-distance target. On the head phantom, no obvious differences in operation time and adjustment time were found among the three performers (P > 0.05). The median adjustment time was significantly less under the guidance of the robot than under free hand. The one-time success rate was significantly higher with the robot (P < 0.05). There was no obvious difference in operation time between the two methods (P > 0.05).

CONCLUSION

In the laboratory environment, accuracy of binocular-stereo-vision-based navigation robot is acceptable for target at 100 mm depth or less. Compared with freehand, foramen ovale placement accuracy can be improved with robot guidance.

Ceftriaxone Relieves Trigeminal Neuropathic Pain Through Suppression of Spatiotemporal Synaptic Plasticity via Restoration of Glutamate Transporter 1 in the Medullary Dorsal Horn

Using a rat model of trigeminal neuropathic pain (TNP) produced by chronic compression of the infraorbital nerve (CCI-ION), we investigated the analgesic effect and the underlying mechanisms of ceftriaxone (Cef), a β-lactam antibiotic, that is thought to be a potent stimulator of glutamate transporter 1 (GLT-1). First, repeated intraperitoneal (i.p.) injections of Cef (200 mg/kg) for 5-days since Day 1 of CCI-ION could significantly relieve both mechanical and thermal pain hypersensitivity from day 10 after drug administration. Western blot and immunofluorescent results demonstrated that 5-days administration of Cef resulted in the restoration of GLT-1 expression to a level equivalent to the sham control which was dramatically lost under the TNP condition. Moreover, multi-electrode (8 × 8) array recordings of network field excitatory postsynaptic potentials (fEPSPs) were performed on the acutely dissociated medullary dorsal horn slice evoked by electrical stimulation of the trigeminal spinal tract. The results showed that the increased number of fEPSPs, induction rate, and maintenance of long-term potentiation caused by CCI-ION were significantly suppressed by 5-days administration of Cef. Taken together, the results indicate that Cef can relieve TNP through suppression of spatiotemporal synaptic plasticity via GLT-1 restoration in the medullary dorsal horn of the trigeminal nerve.

Pilot Study of Injection of OnabotulinumtoxinA Toward the Sphenopalatine Ganglion for the Treatment of Classical Trigeminal Neuralgia

Background

The sphenopalatine ganglion (SPG) has previously been targeted in trigeminal neuralgia (TN), but its role in this condition has not been established.

Objective

To investigate the safety of injecting onabotulinumtoxinA (BTA) toward the SPG using the MultiGuide^® in 10 patients with refractory classical TN, and collect preliminary efficacy data.

Methods

Twenty‐five international units (IU) of BTA were injected toward the SPG in a prospective, open‐label study in 10 patients with refractory classical TN. All patients were recruited and treated on an out‐patient basis at St. Olav's University Hospital in Trondheim (Norway). Primary outcome: adverse events (AEs). Primary efficacy outcome: number of TN attacks at weeks 5‐8 after injection compared to baseline. A treatment responder was predefined as at least 50% reduction in the median number of attacks per day between baseline and weeks 5‐8. Other efficacy outcomes were intensity of attacks (numeric rating scale, 0 to 10) and functional level (1 to 4; 1 best and 4 worst) at weeks 5‐8 after injection compared to baseline. Percentage of the day with concomitant persistent pain was registered at baseline and at weeks 1‐4, 6, 8, and 12 after injection. Patient global impression of change (PGIC) was ascertained at month 3.

Results

For the primary endpoint, we analyzed data for all 10 patients. For efficacy outcomes we analyzed data for 9 patients (1 patient violated protocol). We registered 13 AEs, none of which were serious. The median number of TN attacks during the 4‐week baseline and weeks 5‐8 after injection was 5.5 (range: 1.0‐51.5) and 5 (range: 0‐225.0), respectively (P = .401). Four patients were treatment responders. The median intensity of attacks at baseline and weeks 5‐8 after injection was 6 (range: 3.0‐8.5) and 3 (range: 0.0‐9.0) respectively (P = .024). The median functional level at baseline was 2 (range: 1.0‐3.3) and at month 2, 1 (range 1.0‐4.0; P = .750). Median percentage of the day with concomitant persistent pain was 75% (minimum 37.5%, maximum 100%) at baseline and 18.75% (minimum 0%, maximum 100%) at week 8 (P = .023).

Conclusions

Injection of BTA toward the SPG using the MultiGuide^® in patients with TN appears to be safe and well tolerated. This study was negative for the main efficacy endpoint (reduction in the number of attacks from baseline to weeks 5‐8). Further studies examining the role of the SPG in TN are necessary.

Computer-Assisted Design Template Guided Percutaneous Radiofrequency Thermocoagulation through Foramen Rotundum for Treatment of Isolated V2 Trigeminal Neuralgia: A Retrospective Case-Control Study

Objective

Radiofrequency thermocoagulation (RFT) through the foramen rotundum has emerged as an alternative for treatment of isolated V2 trigeminal neuralgia. But puncture of the foramen rotundum is difficult and time-consuming. In current study, we introduced the application of a computer-assisted design (CAD) template to guide foramen rotundum cannulation. Meanwhile, we assessed its safety and efficacy in the treatment of isolated V2 trigeminal neuralgia.

Methods

From November 2015 to August 2017, thirty-eight patients with isolated V2 trigeminal neuralgia were treated with computed tomography- (CT-) guided RFT through the foramen rotundum in our institution. All cases were reviewed, and patients were divided into the experimental group (n=17, puncture with a CAD template) and control group (n=21, free-hand puncture) according to the puncture method used. The puncture times, duration of puncture, and duration of operation were collected. The outcome of pain remission was evaluated utilizing the Barrow Neurological Institute's (BNI) pain score. Complications and recurrence of pain were also recorded. Data were compared between groups.

Results

The rate of one-time successful puncture in the experimental group was obviously higher than that in the control group. Mean puncture times in the experimental group was fewer. Average duration of puncture and operation in the experimental group was also shorter than that in the control group. All patients experienced good pain remission (BNI Class I or II) postoperatively. At four follow-up points (7 days, 3 months, 6 months, and 12 months after operation), there was no significant difference in good pain relief rate between the two groups. Meanwhile, no significant difference was found in complications.

Conclusions

CAD template is a safe and precise navigation instrument for RFT treatment of isolated V2 trigeminal neuralgia via the foramen rotundum. Therefore, this novel tool is worthy of clinical promotion.

Treatment of trigeminal neuralgia by radiofrequency of the Gasserian ganglion

Trigeminal neuralgia (TN) is a neuropathic pain disorder that affects the trigeminal nerve distribution area. Pharmacological therapy has remained the first-line treatment for TN. If pharmacological intervention is not effective, surgical treatments including radiosurgery (mainly gamma knife therapy), radiofrequency (RF) of the Gasserian ganglion, and microvascular decompression have been utilized. RF is one of the most common procedures used to treat TN. Two RF approaches are commonly utilized: conventional radiofrequency (CRF) and pulsed radiofrequency (PRF). Both methods have been used to successfully treat TN; however, each procedure has distinct advantages and disadvantages. This article summarizes the current relevant literature to compare the treatment of TN with CRF vs. PRF. We discuss the treatment indications, operative methods, and complications of each treatment strategy. Most of the patients treated with CRF had a satisfactory outcome, whereas most PRF patients still had significant pain after the procedure. The application of a higher voltage can improve the curative effect of PRF, and its complications are less than CRF. Both CRF and PRF can be used to treat TN, and the former was more effective. Although the complications of CRF are more than those of PRF, most of them were short-lived and lacked sequelae. The pain relief rate in PRF-treated patients was significantly lower compared to CRF-treated patients. Furthermore, recurring pain was more commonly observed in PRF-treated patients. Therefore, CRF may be the preferred treatment option for TN, whereas treatment with PRF requires further study.

Subcutaneous Trigeminal Nerve Field Stimulation for Refractory Facial Pain

Chronic or neuropathic trigeminal facial pain can be challenging to treat. Neurosurgical procedures should be applied when conservative treatment fails. Neuromodulation techniques for chronic facial pain include deep brain stimulation and motor cortex stimulation, which are complex to perform. Subcutaneous nerve field stimulation is certified for chronic back pain and is the least invasive form of neuromodulation. We applied this technique to treat chronic and neuropathic trigeminal pain as an individual therapy concept. First, trial stimulation is performed. Subcutaneous leads are placed in the painful trigeminal dermatome under local anesthesia. The leads are connected to an external neurostimulator that applies constant stimulation. Patients undergo a 12 day outpatient trial to assess the effect of the stimulation. Electrodes are removed after the trial. If the patient reports pain reduction of at least 50% in intensity and/or attack frequency, a reduction in medication or increase in quality of life, permanent implantation is scheduled. New electrodes are implanted under general anesthesia and are subcutaneously tunneled to an infraclavicular internal pulse generator. Patients are able to turn stimulation on and off and to increase or decrease the stimulation amplitude as needed. This technique represents a minimal invasive alternative to other more invasive means of neuromodulation for trigeminal pain such as motor cortex stimulation or deep brain stimulation.

A retrospective study of neurocombing for the treatment of trigeminal neuralgia without neurovascular compression

BACKGROUND

Microvascular decompression (MVD) is the most effective and non-ablative treatment for trigeminal neuralgia (TN). However, it is not possible when neurovascular compression (NVC) is absent. Neurocombing is a possible treatment option for TN patients without NVC.

AIM

To evaluate and describe the clinical outcome of neurocombing for the treatment of TN when NVC was absent.

METHODS

We retrospectively reviewed the clinical data of the 37 patients of Type 1 TN without NVC who underwent neurocombing in our department between January 2013 and November 2014. The Barrow Neurological Institute (BNI) Pain Intensity scale, the numerical rating scale (NRS) and the quality of life scale (QOL) were evaluated in four stages-presurgical, immediate, at 1 and at 3 years. Pain recurrence was statistically evaluated with Kaplan-Meier analysis.

RESULTS

All the 37 enrolled patients were proved to have no NVC by imaging or exploration in surgery. The mean follow-up duration was 29.50 months. After the procedure, 35 patients (94.6%) experienced immediate pain relief (BNI I) and 2 patients (5.4%) had occasional pain without any medication (BNI II). At 1 year and 3 years, the rates of successful pain relief (BNI I&II) were 86.5 and 83.3%, respectively. 34 patients (91.9%) suffered from mild facial numbness, while it did not exert a harmful impact on their quality of life.

CONCLUSIONS

This study demonstrated that neurocombing is an attractive, effective, safe and durable treatment option for TN when NVC is absent. Further study is needed to explain the complicated and exact mechanism of pain relief by neurocombing.

Angular Relationship Between the Foramen Ovale and the Trigeminal Impression: Percutaneous Cannulation Trajectories for Trigeminal Neuralgia

The debilitating pain of trigeminal neuralgia often necessitates neurosurgical intervention via percutaneous transovale cannulation. While most percutaneous treatments of trigeminal neuralgia are successful, severe adverse events resulting from failure to properly cannulate the foramen ovale (FO) have been reported. With regard to specific targeting of particular trigeminal divisions (ie, V1, V2, V3, and combinations thereof), operative techniques have been described; however, these descriptions have not included specific angulation data. This anatomic study analyzed the angular relationship between the centroid and anteromedial- and posterolateral-most aspects of the FO and the boundaries of the trigeminal impression. The study is the first to detail the angular relationship between the FO boundaries and the boundaries of the trigeminal impression in dry human skulls relative to the coronal plane. The information may be used to prevent miscannulation and also target specific branches of the trigeminal nerve for optimal operative results.

A Clinical Analysis of Secondary Surgery in Trigeminal Neuralgia Patients Who Failed Prior Treatment

Objective

Although many treatment modalities have been introduced for trigeminal neuralgia (TN), the long-term clinical results remain unsatisfactory. It has been particularly challenging to determine an appropriate treatment strategy for patients who have responded poorly to initial therapies. We analyzed the surgical outcomes in TN patients who failed prior treatments.

Methods

We performed a retrospective analysis of 37 patients with recurrent or persistent TN symptoms who underwent surgery at our hospital between January 2010 and December 2014. Patients with follow-up data of at least one year were included. The prior treatment modalities of the 37 patients included microvascular decompression (MVD), gamma knife radiosurgery (GKRS), and percutaneous procedures such as radiofrequency rhizotomy (RFR), balloon compression, and glycerol rhizotomy (GR). The mean follow-up period was 69.9 months (range : 16–173). The mean interval between the prior treatment and second surgery was 26 months (range : 7–123). We evaluated the surgical outcomes using the Barrow Neurological Institute (BNI) pain intensity scale.

Results

Among the 37 recurrent or persistent TN patients, 22 underwent MVD with partial sensory rhizotomy (PSR), 8 received MVD alone, and 7 had PSR alone. Monitoring of the surgical treatment outcomes via the BNI pain intensity scale revealed 8 (21.6%) patients with a score of I, 13 (35.1%) scoring II, 13 (35.1%) scoring III, and 3 (8.2%) scoring IV at the end of the follow-up period. Overall, 91.8% of patients had good surgical outcomes. With regard to postoperative complications, 1 patient had transient cerebrospinal fluid rhinorrhea (2.7%), another had a subdural hematoma (2.7%), and facial sensory changes were noted in 8 (21.1%) patients after surgery.

Conclusion

Surgical interventions, such as MVD and PSR, are safe and very effective treatment modalities in TN patients who failed initial or prior treatments. We presume that the combination of MVD with PSR enabled us to obtain good short- and long-term surgical outcomes. Therefore, aggressive surgical treatment should be considered in patients with recurrent TN despite failure of various treatment modalities.

Orientation of the Foramen Ovale: An Anatomic Study With Neurosurgical Considerations

Unsuccessful cannulation of the foramen ovale (FO) continues to occur with both fluoroscopic technique and technique using computed tomography paired with navigational technology. Despite advances in stereotactic neurosurgical imaging and technique, anatomic variation of the FO occasionally prevents successful cannulation. Morphometric study of the FO has been limited to length, width, and area parameters; therefore, this report analyzed the orientation of the FO. A total of 139 crania (235 foramina ovalae) were photographed and assessed digitally by ImageJ software (NIH). Foramina were fit with a best fit ellipse. For orientation, the midsagittal plane was located by bisecting the basilar process of the occiput; the coronal plane was identified as perpendicular to the midsagittal plane. The angles between the major axis of the best fit ellipse of the FO and the midsagittal and coronal planes were measured. The angle formed between the major axis of the best fit ellipse of the FO and the coronal plane averaged 35.43° ± 9.74° (mean ± SD) on the left and 36.47° ± 7.60° on the right. The angle formed between the major axis of the best fit ellipse of the FO and the sagittal plane averaged 54.57° ± 9.74° on the left and 53.53° ± 7.60° on the right. No significant difference was found between FO orientation among the sexes. Understanding the orientation of the FO may aid in stereotactic neurosurgical planning and successful cannulation of the FO.

Treatment of bilateral idiopathic trigeminal neuralgia by radiofrequency thermocoagulation at different temperatures

Radiofrequency thermocoagulation (RFT) is an effective treatment for trigeminal neuralgia, but consensus regarding an optimal treatment temperature is lacking. While treatment temperatures ranging from 60°C to 95°C have been reported, RFT at too high a temperature is often followed by serious complications, and comparative evaluations of RFT at different temperatures in a single study are rare.This current prospective cohort study was to compare immediate and long-term outcomes of RFT at varying temperatures in patients with bilateral idiopathic trigeminal neuralgia (ITN) of maxillary division of trigeminal nerve (V2), mandibular division of trigeminal nerve (V3), and V2+V3, including pain relief, complications, recurrence rate, and patient satisfaction. From May 2011 to April 2016, 62 consecutive patients with bilateral ITN of V2, V3, and V2+V3 were enrolled in the study. These patients underwent bilateral RFT at 68°C and 75°C, respectively, using the same RF parameters. Side-to-side results, including pain relief, complications, and patient satisfaction, were compared during a 5-year follow-up period.Overall pain relief was satisfactory after RFT. The rate of pain relief after treatment at 75°C was slightly higher than at 68°C (P > 0.05). The pain-free rate was 95.1% at 75°C and 93.5% at 68°C at 1 year, 84.3% and 78.1% at 3 years, and 80.7% and 74.4% at 5 years. There were 10 and 13 cases of recurrence, respectively, and 6 cases of bilateral recurrence. The incidence and severity of complications were greater at 75°C (P < 0.05) than at 68°C, and therefore the patient satisfaction at the higher temperature was lower (P < 0.05).Patients with bilateral ITN who underwent RFT at different temperatures had consistent pain relief after RFT at both 75°C and 68°C, but there were fewer and less severe complications at 68°C, which was accompanied by greater patient satisfaction. This suggests that RFT at lower temperatures may be preferable, and that a temperature of 68°C can be recommended.

Radiofrequency thermocoagulation for V2/V3 idiopathic trigeminal neuralgia: effect of treatment temperatures on long-term clinical outcomes: A Cohort Study

Radiofrequency thermocoagulation (RFT) is widely used to treat trigeminal neuralgia (TN); however, the optimal temperature at which RFT is most efficacious remains under much debate. Thus, the aim of the present study was to determine the lowest temperature at which morbidity could be minimized and patient outcomes maximized.A multivariate analysis was used to study 1354 patients who underwent computed tomography (CT)-guided RFT for V2/V3 idiopathic trigeminal neuralgia (ITN) during from June 2006 to May 2015. RFT was carried out at 62, 65, and 68°C, while keeping all other RF parameters the same. This was a prospective cohort study, in which we assessed intra- and postoperative complications, pain relief, and long-term health-related quality of life (HRQoL).The intraoperative and in-hospital complications of patients were mainly facial hematoma, mouth and external auditory meatus penetration, nausea, vomiting, dizziness, and headache, which were all treated symptomatically. In long-term follow-up, patients with pain relief (defined as no pain and no required drug intervention) at 62, 65, and 68°C accounted for 94.2%, 98.3%, and 98.8% (at discharge); 83.8%, 90.1%, and 91.4% (at 1 year); 66.7%, 80.5%, and 88.2% (at 3 years); 59.0%, 64.3%, and 77.2% (at 5 years); 48.7%, 57.8%, and 72.3% (at 7 years); 40.6%, 53.7%, and 60.3% (at 9 years), respectively. The number of patients with facial numbness, masticatory atonia, or corneal hypoesthesia was increased with the elevation of temperature, but these complications were all mild. No blindness, deafness, intracranial hemorrhage, or death as a result of the surgical intervention occurred in any patients. SF-36 scores showed highest HRQoL in the group treated at 68°C, followed by the 65 and 62°C groups, respectively.Our results demonstrate that 68°C is a good choice for RFT of V2/V3 ITN. The alternative option is 65 or 62°C for RFT to minimize the occurrence of complications including facial numbness, yet which often yields a higher recurrence rate.

Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia Using a Single-Plane, Flat Panel Detector Angiography System: Technical Note

Percutaneous treatments for trigeminal neuralgia (TN) including glycerol rhizotomy (GR), radiofrequency thermocoagulation (RT), and balloon compression (BC) are effective for patients with medical comorbidities and risk factors of microvascular decompression (MVD). These procedures are usually performed under fluoroscopy. Surgeons advance the needle to the trigeminal plexus through the foramen ovale while observing landmarks of fluoroscopic images; however, it is sometimes difficult to appropriately place the needle tip in Meckel's cave. We present the technical details of percutaneous GR using a single-plane, flat panel detector angiography system to check the needle positioning. When the needle tip may be located near the trigeminal cistern, three-dimensional (3-D) bone images are taken with cone-beam computed tomography (CT). These images clearly show the position of the needle tip in Meckel's cave. If it is difficult to place it through the foramen ovale, surgeons perform cone beam CT to observe the actual position of the needle tip at the skull base. After confirming the positional relation between the needle tip and foramen ovale, surgeons can advance it in the precise direction. In 10 procedures, we could place the nerve-block needle in about 14.5 minutes on average without complications. We think that our method is simple and convenient for percutaneous treatments for TN, and it may be helpful for surgeons to perform such treatments.

Comparing Percutaneous Treatments of Trigeminal Neuralgia: 19 Years of Experience in a Single Centre

BACKGROUND

Glycerol rhizolysis, thermocoagulation, and balloon compression are well established in the treatment of trigeminal neuralgia.

OBJECTIVE

To compare the outcome profile of these 3 percutaneous procedures in a single centre over a long follow-up period.

METHODS

Over 19 years, 393 procedures were performed on 210 trigeminal neuralgia patients. Patient records and telephone follow-up were used to determine demographic and operative details and surgical outcomes. The length of follow-up extended to over 17 years.

RESULTS

The initial rates of complete pain relief with or without medication were 72% for glycerol, 80% for thermocoagulation, and 86% for balloon compression. Kaplan-Meier analysis of recurrence times showed that balloon compression provides significantly longer relief than the other 2 procedures. Complication rates for glycerol, thermocoagulation, and balloon compression were 30.3, 27.1, and 43.5%, respectively. Analysis of repeat procedures showed no difference in recurrence times for balloon compression or thermocoagulation compared with primary procedures, but repeat glycerol procedures gave shorter recurrence times.

CONCLUSION

Balloon compression provides longer pain relief than glycerol and thermocoagulation. Although balloon compression is more likely to give numbness and complications, the complications are largely minor and transitory. Moreover, balloon compression following previous percutaneous procedures remains highly effective.

Laser speckle imaging to improve clinical outcomes for patients with trigeminal neuralgia undergoing radiofrequency thermocoagulation

OBJECTIVE

Percutaneous treatments for trigeminal neuralgia are safe, simple, and effective for achieving good pain control. Procedural risks could be minimized by using noninvasive imaging techniques to improve the placement of the radiofrequency thermocoagulation probe into the trigeminal ganglion. Positioning of a probe is crucial to maximize pain relief and to minimize unwanted side effects, such as denervation in unaffected areas. This investigation examined the use of laser speckle imaging during probe placement in an animal model.

METHODS

This preclinical safety study used nonhuman primates, Macaca nemestrina (pigtail monkeys), to examine whether real-time imaging of blood flow in the face during the positioning of a coagulation probe could monitor the location and guide the positioning of the probe within the trigeminal ganglion.

RESULTS

Data from 6 experiments in 3 pigtail monkeys support the hypothesis that laser imaging is safe and improves the accuracy of probe placement.

CONCLUSIONS

Noninvasive laser speckle imaging can be performed safely in nonhuman primates. Because improved probe placement may reduce morbidity associated with percutaneous rhizotomies, efficacy trials of laser speckle imaging should be conducted in humans.

Technical considerations and outcome assessment in retrogasserian balloon compression for treatment of trigeminal neuralgia. Series of 901 patients

BACKGROUND

The aim of our study was to describe the retrogasserian balloon compression (RGBC) procedure with some personal tricks and to assess the long-term results.

METHODS

Between 1985 and 2012, 901 patients, suffering from refractory trigeminal neuralgia (TN), underwent RGBC procedure in our department. Concerning the surgical technique, the introducer was in close contact with the posterior extremity of the horizontal plate of the palatine bone and had the direction of the bisector of the angle clivus-superior edge of the petrous bone on an X-rays sagittal view. No metallic material was inserted intracranially. The balloon was inflated with 0.7 cc of contrast medium for 6 min.

RESULTS

At 1 month follow up, appreciable pain relief was obtained in 835 patients (92.7%). At 1 year, results were excellent in 605 patients (67.1%), satisfactory in 109 patients (12.1%), poor in 57 patients (6.3%), fair in 66 patients (7.3%), whereas recurrences were observed in the remaining 64 patients (7.2%). At mean follow up of 16,5 years, 559 (62%) patients remained pain free. Twenty six patients (2,8%) continued to experience severe pain. Recurrences occurred in two hundred and fifty patients (27,8%). Fifty two of them were operated on a third time and 22 underwent four procedures.

CONCLUSION

RGBC IS AN APPROPRIATE AND EFFECTIVE PROCEDURE FOR TREATMENT OF REFRACTORY TN, ENSURING A LONG LASTING PAIN RELIEF PREDICTED ON THREE FACTORS: pear shape of the balloon, its volume, and duration as mentioned earlier.