Retrogasserian trigeminal radiofrequency-thermorhizotmoy for trigeminal neuralgia.

Based on a personal experience of 4200 surgeries, radiofrequency thermocoagulation is useful lesional treatment for those trigeminal neuralgias (TNs) not amenable to microvascular decompression (idiopathic or secondary TNs). Introduced through the foramen ovale, behind the trigemnial ganglion in the triangular plexus, the needle is navigated by radiology and neurophysiological testing to target the retrogasserian fibers corresponding to the trigger zone. Heating to 55-75 °C can achieve hypoesthesia without anaesthesia dolorosa if properly controlled. Depth of anaesthesia varies dynamically sedation for cannulation and lesioning, and awareness during neurophysiologic navigation. Proper technique ensures long-lasting results in more than 75% of patients.

Riveting technique in percutaneous balloon compression for trigeminal neuralgia remedy.

BACKGROUND: The percutaneous balloon compression (PBC) is a safe and simple treatment for trigeminal neuralgia. It works by compressing the Gasserian ganglion to block pain signals from the trigeminal nerve. To ensure effectiveness, it is important to focus the compression on the lower part of the balloon. OBJECTIVE: To validate the efficacy of a riveting technique, specifically pulling an inflated balloon, in order to apply enhanced compression on the ganglion. METHODS: To compare this novel technique with the conventional approach, a retrospective investigation was conducted on consecutive PBCs performed in our department between 2019 and 2022. For postoperative outcome assessment, efficacy was defined as achieving a VAS score of 0 or an improvement exceeding 5 points. Postoperative numbness was graded as none, mild, or severe based on its impact on daily life and tolerance level. RESULTS: Excluding cases with missed follow-up, a total of 179 participants were included in the study, and their follow-up period ranged up to 40 months. Postoperatively, symptomatic remission was achieved by 98.1% (52/53) of patients in the riveting technique group compared to 87.3% (110/126) in the conventional group (P<0.05). At the last follow-up period, with recurrence observed over time, the long-term efficacy of riveting and conventional groups were 94.3% and 74.6%, respectively (P<0.05). The majority of cases in both groups experienced ipsilateral facial numbness immediately following PBC, which appeared to diminish after 3 months in both groups without significant difference between them (P>0.05).

Anatomical measurements of trigeminal ganglion: a cadaver study.

It is difficult to obtain specific information regarding the trigeminal ganglion (TG), especially pediatric TG. The aim of present study was to determine the parameters of the TG and assist in the neuroablative treatment of trigeminal neuralgia (TN). Thirty-seven sides of cadaver heads that had undergone gross anatomical examination were included, with 29 sides of adults and 8 sides of infants. The distance and angles were measured among 12 points, with nine points adjacent to the TG and three points on the foramen ovale (FO). The three points on FO were represented as three different surgical approaches for TN: posterior FO approach (PFO), lateral FO approach (LFO), and anterior FO approach (AFO). A high similarity was found in pediatric TG. No statistical difference was detected in either the distance or the angles between the 12 points. Statistical difference was found in adult heads in some of the distances, which included PFO to point 5 (17.97 ± 3.35 mm in the left and 15.52 ± 2.28 mm in the right; p = 0.03) and LFO to point 5 and point 8. Moreover, the angle for PFO to point 5 showed a statistically significant difference (60.10 ± 14.02 in the left and 46.63 ± 10.48 in the right; p = 0.01). These findings revealed that surgical neuroablation for patients with TN should be performed more carefully when the PFO or LFO approach is adopted, with a precise preoperative evaluation to avoid corneal complications. Two safety radiofrequency rhizotomy points are also presented to deal with two different kinds of TN.

Variants of the Anterior Subtemporal Approach to the Gasserian Ganglion and Related Structures: An Anatomical Study With Relevant Implications for Keyhole Surgery.

BACKGROUND: The advantages and limitations of different craniotomy positions and approach trajectories to the gasserian ganglion (GG) and related structures using an anterior subtemporal approach have not been studied systematically. Knowledge of these features is of importance when planning keyhole anterior subtemporal (kAST) approaches to the GG to optimize access and minimize risks. METHODS: Eight formalin-fixed heads were used bilaterally to assess temporal lobe retraction (TLR), trigeminal exposure, and relevant anatomical aspects of extra- and transdural classic anterior subtemporal (CLAST) approaches compared with slightly dorsally and ventrally allocated corridors. RESULTS: TLR to the GG and foramen ovale was found to be lower via the CLAST approach (P < 0.001). Using the ventral variant, TLR to access the foramen rotundum was minimized (P < 0.001). The overall TLR was maximal using the dorsal variant (P < 0.001) owing to interposition of the arcuate eminence. An extradural CLAST approach required wide exposure of the greater petrosal nerve (GPN) and middle meningeal artery (MMA) sacrifice. Both maneuvers were spared using a transdural approach. Using CLAST, medial dissection >39 mm can enter the Parkinson triangle, jeopardizing the intracavernous internal carotid artery. The ventral variant enabled access to the anterior portion of the GG and foramen ovale without the need for MMA sacrifice or GPN dissection. CONCLUSIONS: The CLAST approach provides high versatility to approach the trigeminal plexus, minimizing TLR. However, an extradural approach jeopardizes the GPN and requires MMA sacrifice. The risk of cavernous sinus violation exists when progressing medially beyond 4 cm. The ventral variant has some advantages to access the ventral structures and avoid MMA and GPN manipulation. In contrast, the usefulness of the dorsal variant is rather limited owing to the greater TLR required.

Fluoroscopic Analysis of Cannula Tip Location During Radiofrequency Thermocoagulation of the Trigeminal Ganglion.

BACKGROUND: Trigeminal neuralgia (TN) is the most common excruciating cranial neuralgia in the elderly population. Radiofrequency thermocoagulation (RFT) of the trigeminal ganglion is an alternative treatment for medically intractable patients with TN. RFT cannula tip position is an important issue since it is related to treatment outcome and patient safety. OBJECTIVES: The purpose of this study was to evaluate the fluoroscopic position of a cannula tip when a maximal stimulation-induced paresthesia was obtained and the treatment outcome using a Barrow Neurological Institute (BNI) pain scale. STUDY DESIGN: Retrospective analysis. SETTING: An interventional pain management practice in South Korea. METHODS: The final cannula tip position obtained under maximal electrical stimulation of the face was analyzed using previously saved fluoroscopic images. RESULTS: The cannula tip was located exactly in the clival line in 10 patients (29.4%) with maxillary division (V2) TN. There were 24 patients of V2 TN (70.5% ) in whom the cannula tip was located below the clival line. Over 50% of cannula tips were located at -11 mm to -15 mm below the clival line in mandibular division (V3) TN. Forty-four patients (83%) who received RFT in the trigeminal ganglion demonstrated BNI I or II. LIMITATIONS: The number of patients with V3 TN was smaller than that of V2 TN. Only short-term efficacy was evaluated, but not long-term efficacy or recurrence rate of facial pain. CONCLUSIONS: Nearly 70% of patients in V2 TN and all patients in V3 TN, the cannula tip was positioned below the clival line. RFT of the trigeminal ganglion showed a successful treatment outcome with BNI I or II in 83% of patients.

Clinical study of puncture technique in single division of the trigeminal ganglion intumescentia.

OBJECTIVE: We explored the feasibility of single-division puncture in the ophthalmic division, maxillary division, and mandibular division of the trigeminal ganglion intumescentia (TGI) and the feasibility of radiofrequency treatment of trigeminal neuralgia. METHODS: According to the previous anatomical image studies, 3D Slicer software was used to analyze the CT images of the patients. The trigeminal ganglion fossa (TGF) was used as the imaging sign. TGI was identified in the sagittal plane along the fiber. The puncture path starts from the TGI center-foramen ovale line, extending outward to the epidermis as the needle insertion point, and extending inward to the division boundary. For lateral puncture, which is blocked by the mandible, the positions of closed mouth, open mouth, and over-open mouth were used. Multiple targets were generated using straight electrodes and curved electrodes to achieve full coverage of TGI. According to the preoperative design, general anesthesia surgery was performed. Xper CT was used for imaging, and the puncture was guided by Xper Guide. Radiofrequency treatment of TGI was conducted. RESULTS: In total, 45 patients with trigeminal neuralgia underwent 50 single-division TGI punctures. The procedure was smooth and the compliance with the design was good. Continuous radiofrequency (CRF) was performed, the VAS scores were 25 times at 70°C, 19 times at 65°C, two times at 60°C, and two times at 50°C (both in the ophthalmic division). Pulsed radiofrequency (PRF) was conducted two times. Within 24 h after the procedure, the VAS scores were all 0. From 1 to 7 days after the procedure, pain recurrence was found in three cases, of whom two cases received pulsed radiofrequency treatment. Patients were followed up for 1-24 months and there were no recurrence. After continuous radiofrequency at 65-70°C, the moderate tactile loss was observed, and nearly half of the patients had food residues on the surgical side after 6 months. After continuous radiofrequency at 60°C, there was mild tactile loss and no food residue. The tactile sensation was slightly decreased after continuous radiofrequency at 50°C, and the tactile sensation was normal the next day. CONCLUSION: Trigeminal ganglion intumescentia single-division radiofrequency is effective and feasible for the treatment of trigeminal neuralgia.

Ultrasound Guidance Combined with C-Arm Fluoroscopy in Selective Semilunar Ganglion Radiofrequency Thermocoagulation Through the Foramen Ovale for Trigeminal Neuralgia: A Randomized Controlled Trial.

OBJECTIVE: To explore the clinical value of ultrasound guidance combined with C-arm guidance during selective semilunar ganglion radiofrequency thermocoagulation via the foramen ovale for trigeminal neuralgia. METHODS: This study enrolled 48 patients diagnosed with trigeminal neuralgia between January 2021 and December 2021 in the Department of Pain Management at Xuanwu Hospital. Patients were randomly and equally divided into a C-arm-only group and an ultrasound-combined-with-C-arm (ultrasound+C-arm) group, according to a random number table. After exclusions, 42 patients were analyzed. Of these, 21 patients underwent selective semilunar ganglion radiofrequency thermocoagulation via the foramen ovale guided by the C-arm alone, whereas 21 patients underwent the same procedure guided by ultrasound combined with C-arm. The number of punctures, the amount of time elapsed until the target area of the semilunar ganglion was punctured, the cumulative dose of radiation exposure, and puncture-related complications were recorded during the operation. Numerical rating scale scores and radiofrequency thermocoagulation-related complications were evaluated preoperatively and at 1 day, 3 days, 7 days, 1 month, and 3 months after surgery. RESULTS: The number of punctures, the amount of time elapsed until the target area of the semilunar ganglion was punctured, and the cumulative dose of radiation exposure were all lower in the ultrasound+C-arm group than in the C-arm-only group (all P < 0.05). No significant differences were found in numerical rating scale scores and radiofrequency thermocoagulation-related complications between the two groups (P > 0.05). No puncture-related complications occurred in either of the groups. CONCLUSION: Ultrasound guidance combined with C-arm guidance could be safely used for puncturing the semilunar ganglion via the foramen ovale, with more efficiency and less radiation exposure than C-arm guidance alone.

New Trigeminal Stimulation Technique with Dorsal Root Ganglion Stimulation Electrode and Maxillary Fixation: Technique Description.

BACKGROUND: Trigeminal neuralgia is considered the worst pain a human being can experience. Initial treatment uses anticonvulsant sodium channel blockers, which relieve pain in approximately 70% of patients. In refractory cases, it is possible to perform ablative treatments, decompressive surgeries, and neuromodulatory techniques. METHODS: This report describes the treatment of a patient with refractory trigeminal neuralgia who continued to have a painful clinical presentation after four surgical procedures and three ablative procedures. The patient presented with severe pain (verbal numerical scale between 9 and 10), manifesting an evident suicidal ideation. A dorsal root ganglion (DRG) stimulation electrode was implanted in the trigeminal ganglion through intraoral puncture with maxillary fixation of the electrode, in order to minimize the chances of displacement. The test phase consisted of implanting a quadripolar electrode for DRG stimulation through puncture lateral to the buccal rim in a fluoroscopic coaxial view. The electrode was fixed to the skin and maintained for 5 days, during which the patient remained completely pain free. After the 5-day test period, the definitive stimulation electrode was implanted, this time with intraoral puncture and maxillary electrode fixation. RESULTS: The patient remains pain free in the 3-month follow-up, with no displacement of the electrode. CONCLUSIONS: The DRG electrode may be considered a therapeutic option in patients with severe trigeminal neuralgia. Controlled studies must be performed to determine the efficacy and safety of the method.

Long-term outcomes and predictors of percutaneous radiofrequency thermocoagulation of Gasserian ganglion for maxillary trigeminal neuralgia: a retrospective analysis of 1070 patients with minimum 2-year follow-up.

OBJECTIVE: To estimate long-term efficacy and safety for maxillary trigeminal neuralgia (TN) using radiofrequency thermocoagulation (RFT) targeted on Gasserian ganglion, and to identify the factors which may influence outcomes after procedure. METHODS: From 2006 to 2019, 1070 patients underwent RFT for the treatment of medically refractory maxillary TN was included. All patients were followed up for at least 2 years. Outcomes and complications were recorded and analysed. Logistic regression analysis was employed to identify risk factors of long-term pain recurrence. Prognostic value was calculated from receiver-operating characteristic curve (ROC). RESULTS: Longitudinal analysis was taken place for 97 non-responders (9.1%) with ineffective pain relief, 253 responders (23.6%) with pain recurrence and 720 responders (67.3%) without pain recurrence. The median pain-free survival (PFS) was 112.0 months (95% CI: 107.5, 116.5). The pain-free rates were 89.9% (95% CI: 88.0-91.8%) at 1 year, 83.8% (95% CI: 81.5-86.1%) at 2 years, 75.4% (95% CI: 72.7-78.1%) at 5 years and 70.2% (95% CI: 67.4-73.0%) at 10 years. Atypical facial pain (HR = 5.373, 95% CI: 2.623-11.004, p < .001), previous facial numbness (HR = 5.224, 95% CI: 3.107-8.784, p < .001) and poor initial response to medication (HR = 3.185, 95% CI: 2.087-4.860, p < .001) were independently associated with long-term pain recurrence. Patients with prognostic index (PI) > 0.25 were identified as high-risk for recurrent TN (HR = 5.575, 95% CI: 3.991-7.788, p < .001). New and worsen facial hypoesthesia was recorded in 77.9% of patients corresponding with BNI score II-IV, and 18.7% reported improved sensation. Severe complication incidence including troublesome dysesthaesia, keratitis and masseter weakness was higher in 80 °C group. CONCLUSIONS: Favourable outcomes were achieved in terms of long-term pain relief and complications rate after RFT for maxillary TN. Patients with typical facial pain, normal facial sensation, and good initial response to medications may have favourable long-term outcomes.Key messagesThis is a retrospective analysis of radiofrequency thermocoagulation (RFT) targeted on Gasserian ganglion for the treatment of maxillary trigeminal neuralgia (TN) during long-term follow-up. Recurrence-free survival among a large sample was assessed and risk factors associated with long-term pain recurrence was identified. It has been verified that inadvertent damage of ophthalmic and mandibular division causes ophthalmic and masticatory complications. Therefore, a more precise needle tip position and thermocoagulation using a relatively low temperature was recommended.

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.

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 balloon compression for trigeminal neuralgia: a how I do it.

BACKGROUND: Surgical treatments for trigeminal neuralgia may include percutaneous techniques including the balloon compression technique. We present here a simple, effective, and safe adaptation of the historical technique described by Mullan in 1978. METHOD: Our procedure is performed in a bi-plane neuro-radiology room. During general anesthesia, 14-G needle is guided under radioscopy to foramen ovale. The 3-F embolectomy catheter is then inserted and inflated with contrast for a period of 2 min 15 s. CONCLUSION: Our technique, performed entirely under bi-plane fluoroscopy, allows a quicker and more precise surgery and avoids errors in guiding the catheter that can result serious injury.

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.

Long-term recurrence-free survival and complications of percutaneous balloon compression and radiofrequency thermocoagulation of Gasserian ganglion for trigeminal neuralgia: A retrospective study of 1313 cases.

OBJECTIVE: To estimate long-term recurrence, complications after percutaneous balloon compression (PBC) and radiofrequency thermocoagulation (RFT) of gasserian ganglion among a large sample of patients with trigeminal neuralgia (TN) during a long-term follow-up. METHODS: A retrospective analysis of 1313 patients undergoing PBC or RFT for the treatment of TN was conducted from 2006 to 2020. Recurrence-free survival (RFS) was assessed by the Kaplan-Meier method. Complications including facial numbness, corneal reflex decrease and masseter weakness were also estimated. RESULTS: For patients who received first initial PBC and RFT, the median RFS was 130.1 months (95% CI: 124.4, 135.9) and 123.3 months (95% CI: 117.6, 128.9) in PBC and RFT group with log-rank p = 0.108. The RFS rate was, respectively, 90.6% (95% CI: 88.1%-93.3%) and 91.4% (95% CI: 89.1%-93.7%) at 1 year, 84.6% (95% CI: 81.4%-87.8%) and 83.3% (95% CI: 80.3%-86.3%) at 3 years, 81.5% (95% CI: 78.1%-85.0%), and 78.6% (95% CI: 75.2%-81.9%) at 5 years, 71.5% (95% CI: 67.5%-75.5%), and 64.8% (95% CI: 61.0%-68.7%) at 10 years in two groups. No significant difference was observed in facial numbness degree between two groups after procedure. Compared with PBC group, ophthalmic complication prevalence was higher in RFT group (9.6%) (p = 0.001). However, masseter weakness incidence was lower (10.7%) than that in PBC group (24.0%) with p < 0.001. CONCLUSIONS: Patients with TN seemed to attain similar long-term benefit from PBC and RFT, especially in elderly. However, in order to reduce postoperative complications, PBC provided a safer and alternative for treating TN involving ophthalmic division, whereas RFT could be employed as a preferred regimen for maxillary and mandibular TN.

Cardiovascular response to Gasserian ganglion ablation on trigeminal neuralgia under local anesthesia: a retrospective single-blind case-control study.

OBJECTIVE: Radiofrequency thermocoagulation of Gasserian ganglion brings with it the difficult problem of how to provide adequate acesodyne therapy for patients in order to make the treatment more comfortable. In our study, we assess the safety and efficacy of lidocaine local anesthesia in the treatment of trigeminal neuralgia. METHODS: From January, 2017 to December, 2020, 80 patients in our hospital who were suffering from trigeminal neuralgia were treated with radiofrequency thermocoagulation through oval foramen. They were all enrolled in our study and randomly divided into a study group and a placebo group. In the study group an appropriate concentration of lidocaine was given outside and inside of the oval foramen after puncturing in place, while in the placebo group the same dose of normal saline was given in the same way. We then recorded the mean arterial pressure (MAP), heart rate (HR) and visual analogue scale (VAS) at different treatment temperatures. RESULTS: The values of MAP and HR in the study group were generally lower than those in the placebo group, and the difference was statistically significant. Additionally, the two groups showed a significant difference in MAP, HR, and VAS at different treatment temperatures. There were significant differences in MAP and VAS between the study group at the baseline as well as each time point thereafter, and the range of MAP and HR in the study group were lower than those in the placebo group. CONCLUSION: Reasonable lidocaine local anesthesia can provide analgesic effects and prevent hypertension and arrhythmia during Gasserian ganglion radiofrequency thermocoagulation for the treatment of trigeminal neuralgia.

A Simple Method for Foramen Ovale Puncture Based on Preoperative Image Simulation in Percutaneous Microcompression of the Trigeminal Ganglion.

BACKGROUND: The classic puncture method of percutaneous microcompression using fluoroscopy might be difficult to precisely locate and visualize the foramen ovale. Various new surgical tools to increase the accuracy of finding the foramen ovale location have been introduced. However, all of these systems require some complicated operating steps and/or advanced devices to complete the work. OBJECTIVE: To describe the use of a simple method for foramen ovale puncture by percutaneous microcompression based on preoperative image simulation. METHODS: Forty-five patients were included in the study. All patients underwent a computed tomography examination. Among them, the simulated preoperative puncture pathway was reconstructed on the basis of computed tomography scan examination for 22 patients. Procedures were performed by 2 surgeons: one experienced surgeon and another young surgeon with surgical qualification. The puncturing time and cumulative radiation exposure dose, from start of the puncturing until reaching the foramen ovale, were recorded. Postoperative pain relief, facial hypoesthesia, masticatory muscle weakness, and other complications were recorded. RESULTS: In all cases, the procedure of cannulation was completed successfully. The puncturing time for both the experienced and young surgeon with the use of preoperative image simulation seemed to be time-saving. The young surgeon had less cumulative radiation exposure with the use of preoperative image simulation. Moreover, the intraoperative puncture pathways were almost consistent with the preoperative simulated images. The rest of the process went smoothly. Short-term outcomes of all the 45 patients were satisfactory. CONCLUSION: Based on our preliminary experience, the preoperative image simulation-guided technique is useful during these cases.

Morphology of the trigeminal ganglion: anatomical structures related to trigeminal radiofrequency rhizotomy.

BACKGROUND: Trigeminal neuralgia is the most common example of craniofacial neuralgia. Its etiology is unknown and is characterized by severe episodes of paroxysmal pain. The trigeminal ganglion and its adjacent anatomical structures have a complex anatomy. The foramen ovale is of great importance during surgical procedures such as percutaneous trigeminal rhizotomy for trigeminal neuralgia. OBJECTIVE: We aimed to identify the anatomical structures associated with the trigeminal ganglion and radiofrequency rhizotomy on cadavers and investigate their relationship with the electrodes used during rhizotomy to determine the contribution of the electrode diameter and length to the effectiveness of the lesion formation on the ganglion. METHODS: Five fresh-frozen cadaver heads injected with red silicone/latex were used. A percutaneous puncture was made by inserting of a cannula through the foramen ovale to create a pathway for electrodes. The relationships between the electrodes, Meckel's cave, trigeminal ganglion, and neurovascular structures were observed and morphometric measurements were obtained using a digital caliper. RESULTS: Trigeminal ganglion, therefore the electrode in its final position, shows proximity with important anatomical structures. The electrode was inserted posteriorly into the foramen ovale in all of the specimens and was located on the retrogasserian fibers. This study revealed that the electrodes targeting the ganglion and passing through the foramen ovale may cause a radiofrequency lesion due to the contact effect of the dura itself pressing on the electrode. Pushing the cannula beyond the petroclival angle may result in puncturing of the dura propria and moving further away from the target area. CONCLUSION: The success of radiofrequency rhizotomy is directly related to the area affected by the lesion. Understanding the mechanism of action underlying this procedure will ensure the effectiveness, success, and sustainability of the treatment.

Extracranial Non-Gasserian Ganglion Application of Radiofrequency Thermocoagulation on the Mandibular Branch of the Trigeminal through the Foramen Ovale for Trigeminal Neuralgia.

BACKGROUND: Percutaneous radiofrequency ablation (RFA) of the trigeminal Gasserian ganglion via the foramen ovale is still one of the classic treatments for primary trigeminal neuralgia. However, the Gasserian ganglion is deep in the middle cranial fossa. Although it is a structure outside the brain tissue, the puncture needle must enter the encephalic to reach the Gasserian ganglion and so it is difficult to completely avoid the risk of intracranial hemorrhage and infection caused by puncture damage to intracranial blood vessels. It is not clear whether if it is possible for RFA at the extracranial non-gasserian-ganglion site via the exit of the cranial channel (foramen ovale) for patients with V3 trigeminal neuralgia (TN). STUDY DESIGN: Prospective, clinical research study. SETTING: Department of Anesthesiology and Pain Medical Center, Jiaxing, China. METHODS: One hundred and seven patients with isolated mandibular branch trigeminal neuralgia were included. Radiofrequency thermocoagulation was performed by CT-guided percutaneous puncture through the foramen ovale. The puncture target was the midpoint of the horizontal transverse diameter of the oval foramen. If the tingling sensation in the mandibular nerve innervation area could be detected, the radiofrequency thermocoagulation (90°C, 120 sec) under intravenous anesthesia would be performed. We investigated the inclination angle, puncture angle and depth, puncture operation time, intraoperative complications and short-term and long-term results after operation. RESULTS: After radiofrequency thermocoagulation, the pain in the mandibular branch dominant area was completely diminished in 104 patients. Two patients were cured after the second radiofrequency treatment. No intracranial hemorrhage not infection complications occurred, except for facial hematoma during operation in 21 cases. After 12-24 months of follow-up, 9 patients had recurrence and were still effective after receiving additional extracranial radiofrequency treatment. LIMITATIONS: A control group should be established and more clinical data should be collected in future work. CONCLUSION: Extracranial non-Gasserian-ganglion RF can achieve satisfactory results and improve the safety of radiofrequency treatment for trigeminal neuralgia.