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.

Localization of Maxillary Artery for Cerebral Revascularization: L-Shaped Perpendicular Two-Step Drilling Technique Stretching from the Foramen Ovale to Rotundum.

BACKGROUND: The use of the maxillary artery (MA) as a donor has increasingly become an alternative method for cerebral revascularization. Localization difficulties emerge due to rich infratemporal anatomical variations and the complicated relationships of the MA with neuromuscular structures. We propose an alternative localization method via the interforaminal route along the middle fossa floor. METHODS: Five silicone-injected adult cadaver heads (10 sides) were dissected. Safe and effective localization of the MA was evaluated. RESULTS: The MA displayed anatomical variations in relation to the lateral pterygoid muscle (LPM) and the mandibular nerve branches. The proposed L-shaped perpendicular 2-step drilling technique revealed a long MA segment that allowed generous rotation to the intracranial area for an end-to-end anastomosis. The first step of drilling involved medial-to-lateral expansion of foramen ovale up to the lateral border of the superior head of the LPM. The second step of drilling extended at an angle approximately 90° to the initial path and reached anteriorly to the foramen rotundum. The MA was localized by gently retracting the upper head of the LPM medially in a posterior-to-anterior direction. CONCLUSIONS: Considering all anatomical variations, the L-shaped perpendicular 2-step drilling technique through the interforaminal space is an attainable method to release an adequate length of MA. The advantages of this technique include the early identification of precise landmarks for the areas to be drilled, preserving all mandibular nerve branches, the deep temporal arteries, and maintaining the continuity of the LPM.

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

BACKGROUND AND OBJECTIVES: Percutaneous trigeminal rhizotomies are common treatment modalities for medically refractory trigeminal neuralgia (TN). Failure of these procedures is frequently due to surgical inability to cannulate the foramen ovale (FO) and is thought to be due to variations in anatomy. The purpose of this study is to characterize the relationships between anatomic features surrounding FO and investigate the association between anatomic morphology and successful cannulation of FO in patients undergoing percutaneous trigeminal rhizotomy. METHODS: A retrospective analysis was conducted of all patients undergoing percutaneous trigeminal rhizotomy for TN at our academic center between January 1, 2010, and July 31, 2022. Preoperative 1-mm thin-cut computed tomography head imaging was accessed to perform measurements surrounding the FO, including inlet width, outlet width, interforaminal distance (a representation of the lateral extent of FO along the middle fossa), and sella-sphenoid angle (a representation of the coronal slope of FO). Mann-Whitney U tests assessed the difference in measurements for patients who succeeded and failed cannulation. RESULTS: Among 37 patients who met inclusion criteria, 34 (91.9%) successfully underwent cannulation. Successful cannulation was associated with larger inlet widths (median = 5.87 vs 3.67 mm, U = 6.0, P = .006), larger outlet widths (median = 7.13 vs 5.10 mm, U = 14.0, P = .040), and smaller sella-sphenoid angles (median = 52.00° vs 111.00°, U = 0.0, P < .001). Interforaminal distances were not associated with the ability to cannulate FO surgically. CONCLUSION: We have identified morphological characteristics associated with successful cannulation in percutaneous rhizotomies for TN. Preoperative imaging may optimize surgical technique and predict cannulation failure.

D-Transposition of the great arteries with restrictive foramen ovale in the fetus: the dilemma of predicting the need for postnatal urgent balloon atrial septostomy.

OBJECTIVE: Restrictive foramen ovale (FO) in dextro-transposition of the great arteries (d-TGA) with intact ventricular septum may lead to severe life-threatening hypoxia within the first hours of life, making urgent balloon atrial septostomy (BAS) inevitable. Reliable prenatal prediction of restrictive FO is crucial in these cases. However, current prenatal echocardiographic markers show low predictive value, and prenatal prediction often fails with fatal consequences for a subset of newborns. In this study, we described our experience and aimed to identify reliable predictive markers for BAS. METHODS: We included 45 fetuses with isolated d-TGA that were diagnosed and delivered between 2010 and 2022 in two large German tertiary referral centers. Inclusion criteria were the availability of former prenatal ultrasound reports, of stored echocardiographic videos and still images, which had to be obtained within the last 14 days prior to delivery and that were of sufficient quality for retrospective re-analysis. Cardiac parameters were retrospectively assessed and their predictive value was evaluated. RESULTS: Among the 45 included fetuses with d-TGA, 22 neonates had restrictive FO postnatally and required urgent BAS within the first 24 h of life. In contrast, 23 neonates had normal FO anatomy, but 4 of them unexpectedly showed inadequate interatrial mixing despite their normal FO anatomy, rapidly developed hypoxia and also required urgent BAS ('bad mixer'). Overall, 26 (58%) neonates required urgent BAS, whereas 19 (42%) achieved good O2 saturation and did not undergo urgent BAS. In the former prenatal ultrasound reports, restrictive FO with subsequent urgent BAS was correctly predicted in 11 of 22 cases (50% sensitivity), whereas a normal FO anatomy was correctly predicted in 19 of 23 cases (83% specificity). After current re-analysis of the stored videos and images, we identified three highly significant markers for restrictive FO: a FO diameter < 7 mm (p < 0.01), a fixed (p = 0.035) and a hypermobile (p = 0.014) FO flap. The maximum systolic flow velocities in the pulmonary veins were also significantly increased in restrictive FO (p = 0.021), but no cut-off value to reliably predict restrictive FO could be identified. If the above markers are applied, all 22 cases with restrictive FO and all 23 cases with normal FO anatomy could correctly be predicted (100% positive predictive value). Correct prediction of urgent BAS also succeeded in all 22 cases with restrictive FO (100% PPV), but naturally failed in 4 of the 23 cases with correctly predicted normal FO ('bad mixer') (82.6% negative predictive value). CONCLUSION: Precise assessment of FO size and FO flap motility allows a reliable prenatal prediction of both restrictive and normal FO anatomy postnatally. Prediction of likelihood of urgent BAS also succeeds reliably in all fetuses with restrictive FO, but identification of the small subset of fetuses that also requires urgent BAS despite their normal FO anatomy fails, because the ability of sufficient postnatal interatrial mixing cannot be predicted prenatally. Therefore, all fetuses with prenatally diagnosed d-TGA should always be delivered in a tertiary center with cardiac catheter stand-by, allowing BAS within the first 24 h after birth, regardless of their predicted FO anatomy.

Radiofrequency Thermocoagulation Through the Foramen Rotundum Versus the Foramen Ovale for V2 Primary Trigeminal Neuralgia: A Systematic Review and Meta-analysis.

BACKGROUND: Percutaneous radiofrequency thermocoagulation (RFT) through the foramen rotundum (FR) is a new approach for the treatment of V2 trigeminal neuralgia (TN). Some studies have shown the novel method seems to have advantages over traditional RFT through the foramen ovale (FO). The optimal interventional surgical strategy for isolated V2 TN remains controversial. OBJECTIVES: The purpose of our study was to perform a systematic review and meta-analysis to evaluate the clinical results of RFT through the FR and the traditional FO puncture approach. STUDY DESIGN: A systematic review of randomized controlled trials for thermocoagulation through the foramen rotundum versus the foramen ovale for V2 primary trigeminal neuralgia. METHODS: Randomized controlled trials or nonrandomized controlled trials published from January 2000 through October 2022 that compared RFT through the FR and the FO for V2 primary TN were found through a comprehensive search in 3 electronic databases (PubMed, EMBASE, Cochrane library). A total of 3 studies (105 patients) were included in this systematic review and meta-analysis. RESULTS: The results indicate that there are no statistically significant differences between the FR group and the FO group in terms of postoperative immediate effect rate (postoperative one week) (P > 0.1; standardized mean difference [SMD] =  0.67 [0.26- 1.71]) and recurrence rate (P > 0.1; SMD = 0.67 [0.26 - 1.71]). The long-term effect rate (postoperative one year) was significantly higher in the FR group (P < 0.05; SMD = 0.12 [0.01 - 0.22]). The FO group had a significantly higher total complication rate compared with the FR group (P < 0.01; SMD = 0.12 [0.03 - 0.53]). LIMITATIONS: The limitations of this systematic review and meta-analysis include the small range of study populations. Heterogeneity caused by inconsistent follow-up time, outcome measurements, and RF parameters are other limitations. CONCLUSION: In conclusion, RFT of the maxillary nerve through the FR for the treatment of primary V2 TN had a better long-term effect rate and fewer complications in comparison with thermocoagulation of the Gasserian ganglion through the FO. No differences were found between both interventions in terms of immediate effect rate and recurrence rate.

A technique to facilitate the cannulation of the foramen ovale for balloon compression.

BACKGROUND: Percutaneous balloon compression is a safe and effective treatment for trigeminal neuralgia. Current technique consists of penetrating the foramen ovale using a sharp 14G needle with a stylet. Difficulty of cannulation of the foramen ovale, failures of cannulation and major neurovascular complications of the procedure, although rare, may be due to the relatively large caliber of this needle and its sharp tip. OBJECTIVE: To present a novel technique to facilitate and make the cannulation of the foramen ovale with a 14G cannula safer. METHODS: A rigid blunt-tip guide of 1.2 or 1.5 mm is used to penetrate the foramen ovale under lateral fluoroscopic control. Once the guide enters the foramen it is advanced further to the clival line, and a 14G cannula is then advanced over the guide to engage the foramen, at which point the guide is withdrawn and replaced with the balloon catheter. RESULTS: The technique was employed to deliver a 4F balloon catheter to Meckel's cave successfully in 500 consecutive procedures performed on 416 trigeminal neuralgia patients. None of the patients had neurovascular complications like facial hematoma, arterial injury, carotid-cavernous fistula or cranial nerve palsies. CONCLUSION: A novel technique for cannulation of the foramen ovale is described. The use of blunt tip guides of smaller diameters instead of sharp 14 G needles considerably facilitated cannulation of the foramen ovale and enabled cannulation in all cases. Absence of complications of cannulation such as facial hematoma, carotid-cavernous fistula or intracranial hemorrhage in this series of patients suggests that the technique may be safer than the use of conventional sharp tipped 14G needles in terms of avoiding neurovascular complications.

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

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

Percutaneous Balloon Compression for Treatment of Trigeminal Neuralgia Assisted by O-Arm O2-Based Navigation: Case Series and Review of the Literature.

BACKGROUND: Percutaneous cannulation of foramen ovale (FO) for treatment of trigeminal neuralgia, classically performed according to empirical landmarks and under fluoroscopic guide, may be difficult, time-consuming, and burdened with vascular or neurological complications related to close anatomic relationships. OBJECTIVE: To investigate cannulation of FO for treatment of trigeminal neuralgia assisted by O-Arm O2-based navigation, to assess safety and accuracy. METHODS: Nineteen patients underwent percutaneous balloon compression of Gasserian ganglion assisted by navigation provided by O-Arm O2 and StealthStation. Clinical outcomes according to Barrow Neurological Institute Pain Score, time of recurrence, side effects, and complications, as well as technical aspects as time of the procedure and number of tracks were investigated and evaluated. Obtained data were compared with current literature in a systematic review. RESULTS: The median time for procedure was 46 minutes; cannulation of the FO was performed in a median of 3 minutes and 47 seconds, in a single track in 16 patients, while 3 cases required a further O-Arm acquisition to check the needle position. No complications were observed. Onset of facial hypoesthesia was recorded in 10 patients and dysesthesia in 5. Although at a median follow-up of 12.7 months 7 patients had recurrence after an average pain-free period of 7.3 months, all but 2 patients had improvement in pain score. CONCLUSION: Advantages powered by navigation should be addressed in accuracy, lower complication rate, and success of cannulation even in case of previous treatments or anatomic variations, rather than in effective reduction of surgical time.

Presurgical video-EEG monitoring with foramen ovale and epidural peg electrodes: a 25-year perspective.

BACKGROUND: Epilepsy surgery cases are becoming more complex and increasingly require invasive video-EEG monitoring (VEM) with intracranial subdural or intracerebral electrodes, exposing patients to substantial risks. We assessed the utility and safety of using foramen ovale (FO) and epidural peg electrodes (FOP) as a next step diagnostic approach following scalp VEM. METHODS: We analyzed clinical, electrophysiological, and imaging characteristics of 180 consecutive patients that underwent FOP VEM between 1996 and 2021. Multivariate logistic regression was used to assess predictors of clinical and electrophysiological outcomes. RESULTS: FOP VEM allowed for immediate resection recommendation in 36 patients (20.0%) and excluded this option in 85 (47.2%). Fifty-nine (32.8%) patients required additional invasive EEG investigations; however, only eight with bilateral recordings. FOP VEM identified the ictal onset in 137 patients, compared to 96 during prior scalp VEM, p = .004. Predictors for determination of ictal onset were temporal lobe epilepsy (OR 2.9, p = .03) and lesional imaging (OR 3.1, p = .01). Predictors for surgery recommendation were temporal lobe epilepsy (OR 6.8, p < .001), FO seizure onset (OR 6.1, p = .002), and unilateral interictal epileptic activity (OR 3.8, p = .02). One-year postsurgical seizure freedom (53.3% of patients) was predicted by FO ictal onset (OR 5.8, p = .01). Two patients experienced intracerebral bleeding without persisting neurologic sequelae. CONCLUSION: FOP VEM adds clinically significant electrophysiological information leading to treatment decisions in two-thirds of cases with a good benefit-risk profile. Predictors identified for electrophysiological and clinical outcome can assist in optimally selecting patients for this safe diagnostic approach.

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.

Identifying a Novel Critical Access Difficulty Factor in Percutaneous Radiofrequency Rhizotomy for Trigeminal Neuralgia: Pterygoid Process Ridge.

BACKGROUND: Percutaneous stereotactic radiofrequency rhizotomy (PSR) is an ablative procedure for trigeminal neuralgia (TN). The anatomic structures that pass through, or around, the foramen ovale (FO) play vital roles in the success rate of PSR. The presence of a variant pterygoid process ridge (PPR) obscuring the FO renders the cannulation procedure difficult but had not been described in the literature before. OBJECTIVE: To identify the variations of the PPR to assess cannulation difficulty. METHODS: Fifty seven FOs of 57 patients with TN (TN group) and 438 FOs of 232 patients without TN (non-TN group) were analyzed using 3-dimensional computed tomography reconstruction images of cranial bases. Three-dimensional printer models were also used for TN patients with PPR-obscured FOs. Measurements were obtained for shape, size, and morphometric variability effect on cannulation. RESULTS: We identified 5 PPR-obscured FOs (8.8%) in the TN group and 32 FOs (7.3%) in the non-TN group. In the TN group, the transverse diameter obstruction ranged from 19.2% to 39.7% in 4 patients, and 1 case was 100%. Of particular note, approximately one-quarter to one-third of FO preset targets were affected by PPR. CONCLUSION: A PPR-obscured FO represents a new confounding factor in the conduct of PSR. Confirming the PPR-obscured FO is a critical step in improving the effectiveness of puncture target presetting, ie, evaluating the target with actual FO data is an improvement over the use of surgical view FO data. Discernment of the PPR can improve the success rate of difficult-to-access FO punctures, thereby rendering PSR more effective.

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.

Anatomical relationship between the foramen ovale and the lateral plate of the pterygoid process: application to percutaneous treatments of trigeminal neuralgia.

Our aim was to clarify the variations in the positional relationship between the base of the lateral plate of the pterygoid process and the foramen ovale (FO), which block inserted needles during percutaneous procedures to the FO usually used for the treatment of trigeminal neuralgia. Ninety skulls were examined. The horizontal relationship between the FO and the posterior border of the base of the lateral plate of the pterygoid process was observed in an inferior view of the skull base. Skulls that showed injury to either the FO or the lateral plate of the pterygoid process on either side were excluded. One hundred and sixty sides of eighty skulls were eligible. The relationship between the FO and the posterior border of the base of the lateral plate was classified into four types. Among the 160 sides, type III (direct type) was the most common (35%), followed by type I (lateral type, 29%) and type IV (removed type, 21%); type II (medial type) was the least common (15%). Of the 80 specimens, 53 showed the same type bilaterally. In type IV, the posterior border of the base of the lateral plate is disconnected from the FO, so percutaneous procedures for treating trigeminal neuralgia could fail in patients with this type.

Infratemporal Fossa Vascular Anatomy Pertinent to Percutaneous Access to the Foramen Ovale for Treatment of Trigeminal Neuralgia: A Comparison of Cadaveric Dissection and Computed Tomography Analysis.

BACKGROUND: Trigeminal neuralgia may be treated via percutaneous access to the foramen ovale (FO). Vascular complications associated with the needle trajectory can result in serious morbidity and mortality. This study aimed to correlate the vascular relationships of the FO at the skull base via cadaveric dissections and computed tomography (CT). METHODS: Two fresh cadaver heads were injected with red and blue latex to delineate arteries and veins. Neck and infratemporal fossa dissections were carried out to delineate the vascular relationships of the FO. High-resolution head CT images of adult patients undergoing neurosurgical evaluations or procedures were analyzed for distances and sizes of skull base foramina in the infratemporal fossa. RESULTS: Three infratemporal fossa dissections (2 cadaveric specimens) were performed. Mean distance of FO to internal carotid artery was 2.4 ± 0.12 cm, and mean distance of FO to middle meningeal artery was 0.8 ± 0.16 cm. Head CT images of 52 patients (104 sides) with 1-mm axial slice thickness were analyzed. Area of the FO was 31.1 ± 9.6 mm2. Distance of FO to internal carotid artery was 1.70 ± 0.31 cm, and distance of FO to middle meningeal artery was 0.73 ± 0.61 cm. CONCLUSIONS: Cadaveric delineation of vascular structures in the infratemporal fossa correlates with head CT imaging and may be used to accurately plan percutaneous access to the FO. Inadvertent puncture of the extracranial internal carotid artery is nearly impossible with good technique. The most likely source of percutaneous vascular injury is the middle meningeal artery and distal branches of the maxillary artery.

Comparison of Efficacy and Safety of CT-Guided Radiofrequency Thermocoagulation Through Foramen Rotundum Versus Foramen Ovale for V2 Primary Trigeminal Neuralgia.

BACKGROUND: Primary trigeminal neuralgia (TN) is one of the most severe facial pain syndromes. TN affects patients' quality of life and, when severe, can lead to depression and increase social burden. OBJECTIVES: This retrospective study aimed to compare efficacy and safety of computed tomographic (CT)-guided percutaneous radiofrequency thermocoagulation (RFT) through the foramen rotundum (FR) versus through the foramen ovale (FO) for treatment of maxillary division (V2) TN. STUDY DESIGN: A prospective study. SETTING: Shengjing Hospital of China Medical University. METHODS: Seventy patients with V2 TN were randomly assigned to 2 groups: RFT-FR group (n = 35) and RFT-FO group (n = 35). Visual Analog Scale (VAS), the Medical Outcomes Study 36-Item Short-Form Health Survey, the total efficacy, complications, and recurrence rate were assessed before and after surgery at different time points. RESULTS: Compared with the preoperative VAS, the postoperative VAS in the RFT-FR and RFT-FO groups both decreased significantly (P < 0.05). There was no significant difference in VAS between the 2 groups (P > 0.05); in both groups quality of life improved to varying degrees after RFT. In the RFT-FO group, the physical component summary (PCS) and mental component summary (MCS) were significantly lower than in the RFT-FR group at 1 week, 2 weeks and 1 month (P < 0.05). After 3 months, the PCS and MCS of the RFT-FO group gradually increased, so the 2 groups no longer differed significantly (P > 0.05). The total incidence of complications in the RFT-FR and RFT-FO groups was 20.0% (7/35) and 62.9% (22/35), respectively, and differed significantly (P < 0.05). LIMITATIONS: This study cohort size is small, but we will gradually increase the number of patients later. Second, there may be acquiescence bias or response bias. Third, the punctures under the more commonly used C-arm imaging guidance deserve to be evaluated in the future. CONCLUSIONS: CT-guided RFT through the FR and FO are both an effective, minimally invasive treatments for V2 TN that can relieve pain effectively.