Recurrent trigeminal neuralgia attributable to veins after microvascular decompression

Repeat Surgery for Recurrent or Refractory Trigeminal Neuralgia: A Systematic Review and Meta-Analysis

OBJECTIVE

Surgery can effectively treat Trigeminal neuralgia (TN), but postoperative pain recurrence or nonresponse are common. Repeat surgery is frequently offered but limited data exist to guide the selection of salvage surgical procedures. We aimed to compare pain relief outcomes after repeat microvascular decompression (MVD), percutaneous rhizotomy (PR), or stereotactic radiosurgery (SRS) to determine which modality was most efficacious for surgically refractory TN.

METHODS

A PRISMA systematic review and meta-analysis was performed, including studies of adults with classical or idiopathic TN undergoing repeat surgery. Primary outcomes included complete (CPR) and adequate (APR) pain relief at last follow-up, analyzed in a multivariate mixed-effect meta-regression of proportions. Secondary outcomes were initial pain relief and facial numbness.

RESULTS

Of 1299 records screened, 61 studies with 68 treatment arms (29 MVD, 14 PR, and 25 SRS) comprising 2165 patients were included. Combining MVD, PR, and SRS study data, 68.8% achieved initial CPR after a repeat TN procedure. On average, 49.6% of the combined sample of MVD, PR, and SRS had CPR at final follow-up, which was on average 2.99 years postoperatively. The proportion (with 95% CI) achieving CPR at final follow-up was 0.57 (0.51-0.62) for MVD, 0.60 (0.52-0.68) for PR, and 0.35 (0.30-0.41) for SRS, with a significantly lower proportion of pain relief with SRS. Estimates of initial CPR for MVD were 0.82 (0.78-0.85), 0.68 for PR (0.6-0.76), and 0.41 for SRS (0.35-0.48).

CONCLUSIONS

Across MVD, PR, and SRS, about half of TN patients maintain complete CPR at an average follow-up time of 3 years after repeat surgery. In treating refractory or recurrent TN, MVD and PR were superior to SRS in both initial pain relief and long-term pain relief at final follow-up. These findings can inform surgical decision-making in this challenging population.

Bibliometric Analysis of the Top 100 Cited Articles and Author H-Indexes on the Surgical Treatment of Trigeminal Neuralgia

INTRODUCTION

Medically refractory cases of trigeminal neuralgia often require treatment escalation. Surgical options include microvascular decompression and percutaneous ablation. This paper provides a bibliometric analysis of the most influential articles on the surgical management of trigeminal neuralgia.

METHODS

The Web of Science database was queried to identify the top 100 cited articles concerning surgical treatment of trigeminal neuralgia. The search terms used included ALL=(("trigeminal neuralgia" OR "tic douloureux" OR "Fothergill's disease" OR "Trifacial neuralgia") AND ("surgical treatment" OR "surgical management" OR "surgery" OR "neurosurgery") NOT ("radiosurgery" OR "gamma knife")). The extracted variables included the first and senior author names, journal, publication year, institution, and surgical modality.

RESULTS

Our bibliometric search yielded 2104 studies, with 41,502 citations overall. Within the top 100 articles, Zakrzewska had the most first author papers (n = 5), and Burchiel had the most senior author papers (n = 6). The Massachusetts General Hospital was the most represented institution (n = 5). The United States was the most represented country (51%). Microvascular decompression was the most studied surgical strategy (51%), followed by percutaneous radiofrequency coagulation (9%), balloon/nerve compression (7%), and glycerol rhizolysis (7%). Some studies assessed multiple treatment modalities (22%). The types of studies included retrospective articles (58%), prospective articles (26%), reviews (10%), anatomic studies (2%), and basic science (1%). Neurosurgery (35%) and the Journal of Neurosurgery (33%) were the most represented journals.

CONCLUSIONS

The current literature consists of retrospective reviews and mostly describes microvascular decompression for trigeminal neuralgia. Future studies should include further characterization of other surgical modalities such as percutaneous radiofrequency thermocoagulation, glycerol injection, and balloon compression.

Online dynamic nomogram for predicting pain recurrence after microvascular decompression in trigeminal neuralgia

Trigeminal neuralgia (TN) is one of the most common causes of facial pain. Microvascular decompression (MVD) is the first-choice surgical treatment. The present study aimed to develop a novel practical assessment system based on preoperative clinical and imaging factors for clinicians to predict the likelihood of pain recurrence following MVD in TN. A total of 56 patients with primary unilateral TN who underwent MVD were retrospectively analyzed. Patients were followed up to observe pain recurrence 1 year after MVD. An online dynamic nomogram was constructed for predicting the probability of pain recurrence after MVD in patients with TN based on multivariate logistic model. The concordance index (C-index) and receiver operating characteristic (ROC) were used to measure model discrimination. Bootstrap resampling was used for internal validation of the model and calibration curve was constructed. Decision curve analysis (DCA) was used to assess clinical applicability. Factors such as numeric rating scale (to score pain degree of patients with TN), response to neuroanalgesic drugs and neurovascular contact on magnetic resonance imaging were independent risk factors affecting the pain recurrence rate (all P<0.05). C-index was 0.973 (95%CI, 0.938-1.000) and the area under the ROC was 0.973 (95%CI, 0.938-1.000). Calibration curve with a 1,000 bootstrap resampling showed a good fit between dynamic nomogram prediction and actual observations. The DCA showed that at a threshold probability between 0 and 100%, this model can achieve a greater net benefit than if all patients had surgery or none had surgery. In conclusion, this online dynamic nomogram reliably predicted risk of pain recurrence in patients with TN following MVD.

Outcome after microvascular decompression for trigeminal neuralgia in a single center-relation to sex and severity of neurovascular conflict

BACKGROUND

Trigeminal neuralgia (TN), a severe type of facial pain, is mainly caused by a neurovascular conflict (NVC). The severity of the NVC seems associated with the outcome following microvascular decompression (MVD) surgery. This study aimed to investigate the outcome after MVD and whether it is affected by NVC severity and sex.

METHODS

TN patients (n = 109) were followed for 5 to 10 years after MVD. Barrow Neurology Index (BNI), Patients Global Impression of Change (PGIC), complications, and time to relapse were evaluated. The NVC severity was retrospectively reviewed from presurgical MRI. Demographic and clinical factors and NVC severity were analyzed for potential association with outcome after MVD.

RESULTS

The success rate (BNI ≤ 2) was 80% after 5 to 10 years follow-up for TN patients with severe NVC (grade 2-3) and 56% for TN patients with mild NVC (grade 0-1, P = 0.003). No sex difference was observed in outcome for patients with both mild (P = 0.924) and severe NVC (P = 0.883) respectively. Three patients (2.8%) during the hospital stay, and two patients (1.8%) at 6 weeks, experienced a complication requiring invasive treatment. At long-term 52/109 patients (47.7%) reported some type of persistent adverse event, of which the majority were mild and required no treatment.

CONCLUSIONS

MVD offers an 80% probability of long-term pain relief in TN patients with severe NVC, with low frequency of serious complications. NVC severity significantly affects outcome after MVD, while no sex differences in outcome were found. In consistency with previous work, the results stress the importance of adequate neuroradiological assessment of the NVC for preoperative patient selection.

Outcomes After Microvascular Decompression for Sole Arterial Versus Venous Compression in Trigeminal Neuralgia

OBJECTIVE

In most cases of trigeminal neuralgia (TN), the trigeminal nerve is compressed by the arterial vasculature. We sought to address the gap in understanding of pain outcomes in patients with sole arterial versus sole venous compression.

METHODS

We retrospectively reviewed all patients undergoing microvascular decompression at our institution, identifying patients with either sole arterial or venous compression. We dichotomized patients into arterial or venous groups and obtained demographics and postoperative complications for each case. Barrow Neurological Index (BNI) pain scores were collected preoperatively, postoperatively, and at final follow-up, as well as recurrence of pain. Differences were calculated via χ2 tests t tests, and Mann-Whitney U Tests. Ordinal regression was used to account for variables known to influence TN pain. Kaplan-Meier analysis was used to determine recurrence-free survival.

RESULTS

Of 1044 patients, 642 (61.5%) had either sole arterial or venous compression. Of these cases, 472 showed arterial compression and 170 showed sole venous compression. Patients in the venous compression group were significantly younger (P < 0.001). Patients with sole venous compression showed worse preoperative (P = 0.04) and final follow-up (P < 0.001) pain scores. Patients with sole venous compression had significantly higher rate of pain recurrence (P = 0.02) and BNI score at pain recurrence (P = 0.04). On ordinal regression, venous compression was found to independently predict worse BNI pain scores (odds ratio, 1.66; P = 0.003). Kaplan-Meier analysis showed a significant relationship between sole venous compression and increased risk of pain recurrence (P = 0.03).

CONCLUSIONS

Patients with TN with sole venous compression show worse pain outcomes after microvascular decompression compared with those with only arterial compression.

Prognostic factors for long-term outcomes of microvascular decompression in the treatment of glossopharyngeal neuralgia: a retrospective analysis of 97 patients

OBJECTIVE

The authors aimed to investigate predictors of postoperative outcomes of microvascular decompression (MVD) for the treatment of glossopharyngeal neuralgia (GPN).

METHODS

A cohort of 97 patients with medically refractory GPN who underwent MVD at the authors' institution between January 2010 and July 2019 was retrospectively reviewed. Univariate and multivariate regression models were used to identify predictors of long-term outcome in patients after MVD.

RESULTS

Eighty-nine patients (91.8%) reported immediate and complete relief of pain after the procedure. Of the remaining 8 patients (8.2%), 6 achieved partial pain relief and pain gradually diminished within 2 weeks after surgery, and 2 did not experience postoperative pain relief. In univariate Cox regression analysis, venous compression of the glossopharyngeal nerve root entry zone (HR 3.591, 95% CI 1.660-7.767, p = 0.001) and lower degree of neurovascular conflict (HR 2.449, 95% CI 1.177-5.096, p = 0.017) were significantly associated with worse pain-free survival. In multivariate Cox regression analysis, venous compression (HR 8.192, 95% CI 2.960-22.669, p < 0.001) and lower degree of neurovascular conflict (HR 5.450, 95% CI 2.069-14.356, p = 0.001) remained independently associated with worse pain-free survival.

CONCLUSIONS

Venous compression of the glossopharyngeal nerve root entry zone and lower degree of neurovascular conflict were significantly correlated with shorter pain-free survival in patients who underwent MVD for GPN. Microvascular decompression is a safe, feasible, and durable approach with a low complication rate for the treatment of GPN.

Purely venous compression in trigeminal neuralgia-can we predict the outcome of surgery

Purpose

Controversies regarding venous compression and trigeminal neuralgia (TN) still exist. The study demonstrates our experience for microvascular decompression (MVD) in TN caused by purely venous compression. The goal was to identify prognostic anatomical or surgical factors that may influence the outcome.

Methods

Between 2004 and 2020, 49 patients were operated with purely venous compression. Average age was 58.4 years. Mean history of TN was 7.8 years. Microsurgical procedures included transposition or separation of the vein, coagulation, and division. Several features have been analyzed with respect to BNI scores.

Results

Evaluation on discharge revealed a complete pain relief in 39 (80%), partial improvement in 7 (14%), and no benefit in 3 (6%) patients. Facial hypesthesia was reported by 14 (28.6%) patients. Mean follow-up (FU) was 42.1 months. BNI pain intensity score on FU revealed 71.4% excellent to very good scores (score 1: 32 (65.3%); 2: 3 (6.1%)). BNI facial numbness score 2 could be detected in 13 patients (26.5%) during FU. There was no statistical relationship between immediate pain improvement or BNI pain intensity score on FU with respect to surgical procedure, size of trigeminal cistern, type of venous compression, venous caliber, trigeminal nerve indentation, or neurovascular adherence. BNI facial numbness score was dependent on type of venous compression (p < 0.05).

Conclusion

We did not find typical anatomical features that could either predict or influence the outcome regarding pain improvement or resolution in any form. Neither classic microvascular decompression (interposition/transposition) nor sacrificing the offending vein made any difference in outcome.

MRI Findings in Trigeminal Neuralgia without Neurovascular Compression: Implications of Petrous Ridge and Trigeminal Nerve Angles

Objective

To determine the anatomical characteristics of the petrous ridge and trigeminal nerve in trigeminal neuralgia (TN) without neurovascular compression (NVC).

Materials and Methods

From May 2017 to March 2021, 66 patients (49 female and 17 male; mean age ± standard deviation [SD], 56.8 ± 13.3 years) with TN without NVC and 57 controls (46 female and 11 male; 52.0 ± 15.6 years) were enrolled. The angle of the petrous ridge (APR) and angle of the trigeminal nerve (ATN) were measured using magnetic resonance imaging with a high-resolution three-dimensional T2 sequence. Data on the symptomatic side were compared with those on the asymptomatic side in patients and with the mean measurements of the bilateral sides in controls. Receiver operating characteristic (ROC) analysis was conducted to evaluate the performance of APR and ATN in distinguishing TN patients from controls.

Results

In TN patients without NVC, the mean ± standard deviation (SD) of APR on the symptomatic side (98.40° ± 19.75°) was significantly smaller than that of the asymptomatic side (105.59° ± 22.45°, p = 0.019) and controls (108.44° ± 15.98°, p = 0.003). The mean ATN ± SD on the symptomatic side (144.41° ± 8.92°) was significantly smaller than that of the asymptomatic side (149.67° ± 8.09°, p = 0.003) and controls (150.45° ± 8.48°, p = 0.001). The area under the ROC curve for distinguishing TN patients from controls was 0.673 (95% confidence interval [CI]: 0.579–0.758) for APR and 0.700 (CI: 0.607–0.782) for ATN. The sensitivity and specificity using the diagnostic cutoff yielding the highest Youden index were 81.8% (54/66) and 49.1% (28/57), respectively, for APR (with a cutoff score of 94.30°) and 65.2% (43/66) and 66.7% (38/57), respectively, for ATN (cutoff score, 148.25°).

Conclusion

In patients with TN without NVC, APR and ATN were smaller than those in controls, which may explain the potential cause of TN and provide additional information for diagnosis.

Surgical treatment for Trigeminal neuralgia

Various treatments for trigeminal neuralgia (TN) are known to yield initial satisfactory results; however, the surgical treatment has excellent long-term outcomes and a low recurrence rate. Surgical treatment addresses the challenge of vascular compression, which accounts for 85% of the causes of TN. As for surgical treatment for TN, microvascular decompression (MVD) has become the surgical treatment of choice after Peter J. Jannetta reported the results of MVD surgery in 1996. Since then, many studies have reported a success rate of over 90% for the initial surgical treatment. Most MVDs aim to separate (decompress) the culprit vessel from the trigeminal nerve. To increase the success rate of surgery, accurate indications for MVD and management of the offender vessels without complications are critical. In addition, if there is no vascular compression, partial sensory rhizotomy or internal neurolysis can be performed to improve surgical outcomes.

Microvascular Decompression for Trigeminal Neuralgia Caused by Venous Offending on the Ventral Side of the Root Entrance/Exit Zone: Classification and Management Strategy

Background

Trigeminal neuralgia (TGN) is typically caused by an offending artery (OA) but may also involve an offending vein. Venous offending on the ventral side of the root entrance/exit zone (VO-VREZ) is particularly challenging.

Objective

To analyze the rate and pattern of VO-VREZ and propose management strategy accordingly.

Methods

VO-VREZ was classified into 3 types based on its anatomical relationship with a nerve root (A, the vein was covered by the nerve root entirely; B, the vein was lateral to the nerve root; and C, the vein penetrated the nerve root) and 3 groups based on the absence/presence of offending artery (I, no OA; II, suspected OA; and III, definitive OA).

Results

The analysis included 143 cases with complete follow-up. Type A, B, and C accounted for 11.9, 31.5, and 56.6% of the cases, respectively. Group I, II, and III accounted for 24.5, 26.6, and 49.0%, respectively. Most group I VO-VREZ cases (26 out of 31) were managed with coagulation followed by division. Most group II VO-VREZ cases (31 out of 38) were decompressed with shredded Teflon interposition. Group III VO-VREZ was left in place in all 70 cases. Immediate pain relief was achieved in all cases. Temporary hemifacial hypesthesia occurred in 21 patients (14.7%), among which 14 were managed with Teflon decompression. Within the 4.5-year median follow-up, pain recurred in 11 patients (7.7%), but all with lesser intensity.

Conclusion

VO-VREZ is not uncommon in patients with TGN. Different management strategy should be chosen according to the anatomical feature and the absence/presence of arterial conflict.

Treatment Strategies for Different Types of Intraneural Offending Vessels in Microvascular Decompression Surgery for Trigeminal Neuralgia: An Analytic Report of 58 Cases

BACKGROUND

Microvascular decompression (MVD) surgery is the treatment of choice for trigeminal neuralgia (TGN). However, decompression becomes difficult when the offending vessel penetrates the trigeminal nerve root.

OBJECTIVE

To estimate the rates and patterns of different types of intraneural offending vessels in patients with TGN for MVD and to discuss respective management strategies.

METHODS

All patients with TGN undergoing MVD in our center from January 1, 2015, to December 31, 2019, were analyzed retrospectively. The intraneural offending vessels included veins and arteries. The postoperative pain relief rate, complications, and recurrences were evaluated.

RESULTS

Of the 302 TGN cases, the intraneural offending vessels were identified in 58 of the cases (19.2%). The 9 cases (15.5%) of intraneural offending arteries were decompressed using shredded Teflon wrapping interposition. Of the 49 cases (84.5%) of intraneural offending veins (INOVs), 29 were not considered true offending vessels, and the treatment only addressed the offending artery in these patients. Of the remaining 20 INOVs, 15 were electrocoagulated and divided, and 5 were decompressed with shredded Teflon. Complete pain relief was achieved in all 58 patients. However, the pain recurred in 5 patients (8.6%), and transient hemifacial numbness occurred in 4 patients (6.9%).

CONCLUSION

Intraneural offending vessels requiring treatment are uncommon and are seen in less than 1 in 10 patients undergoing MVD for TGN. For intraneural offending artery, decompression by shredded Teflon wrapping interposition is recommended. Management of the INOV depends on the individual situations, and the management includes sacrifice, wrapping decompression, or leaving them untreated.

Vein-related Trigeminal Neuralgia: How to Determine the Treatment Method of the Causative Vein: A Technical Note

Trigeminal neuralgia (TN) is often caused by various vein forms. Herein, we report two cases of vein-related TN. In the first case, the vein of the cerebellopontine fissure (VCPF), along with the thickened surrounding arachnoid, clung to the trigeminal nerve. As the perfusion range of this vein was expected to be wide and its injury might cause extensive venous infarction, the anchor between the trigeminal nerve and the vein was carefully dissected and the vein was successfully transposed. In the second case, the involvement of the vein of the middle cerebellar peduncle (VMCP), which penetrates the nerve bundle of the trigeminal nerve, was suspected. Because vein transposition was impossible, the vein was transected at the nerve penetration site after confirming that there was sufficient collateral venous outflow. The superior petrosal vein and its tributaries are the primary causative veins of vein-related TN, and their contact patterns are infinite. Moreover, their perfusion range and the presence or absence of collateral venous outflow vary from case to case. Therefore, it is necessary to judge the perfusion range as well as collateral venous outflow based on preoperative images and intraoperative findings and to determine the appropriate treatment method for each case.

Improving the accuracy of pre-operative evaluation of neurovascular conflict in trigeminal neuralgia using magnetic resonance subtraction

PURPOSE

To investigate the ability of magnetic resonance (MR) subtraction to evaluate neurovascular conflict (NVC) and to compare it with conventional MR protocols.

METHODS

This prospective study included 82 patients with trigeminal neuralgia who underwent microvascular decompression for NVC. All patients had a pre-operative examination using 3T MRI. The MRI protocols used comprised 3D balanced (B)-fast field echo (FFE), 3D steady-state magnetic resonance angiography (MRA), and 3D T1-FFE sequences. MR subtraction images were obtained by subtracting native images from B-FFE and steady-state MRA. NVC evaluation was performed using subtraction images (MR subtraction) and combination images (conventional MR protocols using B-FFE and T1-FFE in combination). Clinical assessment of the degree of compression, the type of compressing vessel, and the location of conflict were undertaken by two independent observers. The two methods were then compared using surgical criteria.

RESULTS

MR subtraction exhibited greater accuracy than the conventional method in terms of the estimated severity of conflict (87.80% vs. 57.32%, p < 0.05), and demonstrated better consistency with surgical findings (k = 0.794 vs. k = 0.365, p < 0.05). For the type of compressing vessel and the location of conflict, both methods were highly accurate and agreed to a similar extent with surgical findings (p = 0.987, compressing vessel; p = 0.665, location of conflict).

CONCLUSION

MR subtraction proved reliable in NVC pre-operative evaluation, with increased accuracy when estimating severity. This result strongly supports the wider use of MR subtraction as the preferred choice in clinical application.

Long-Term Retrospective Analysis of Microvascular Decompression in Patients With Recurrent Trigeminal Neuralgia

Objective: To explore the clinical characteristics of patients with recurrent trigeminal neuralgia (TN) and the experience of microvascular decompression (MVD) in the treatment of such patients. Methods: We retrospectively analyzed clinical data, imaging examination results, surgical methods, and treatment efficacies in 127 patients with recurrent typical TN from January 2005 to December 2014. Results: The age of the recurrent group was higher than that of the non-recurrent group (p < 0.05). The duration of pain before the first MVD procedure was longer in the recurrent group than in the non-recurrent group (p < 0.05). Patients in the recurrent group were more likely to have compression of the trigeminal nerve by the vertebrobasilar artery (VBA) or multiple vessels than patients in the non-recurrent group (p < 0.05). A Kaplan-Meier curve showed a median pain-free survival of 12 months after the first MVD procedure. The severity of pain (preoperative visual analog scale [VAS] score) in patients with recurrence was lower than that in patients with first-onset TN (p < 0.05). Vessel compression, Teflon compression or granuloma and arachnoid adhesion were considered the main causes of recurrence. Postoperative Barrow Neurological Institute (BNI) scores in the redo MVD group were excellent (T = 2) for 69 patients (53.33%) and good (T = 3) for 46 patients (36.22%). The postoperative follow-up was 63-167 months (105.92 ± 25.66). During the follow-up, no recurrence was noted. All complications were cured or improved. Conclusions: Microvascular decompression (MVD) is an effective surgical method for the treatment of TN. For recurrent patients, reoperation can achieve good results.

Characteristics and management of the offending veins in microvascular decompression surgery for trigeminal neuralgia

The optimal technique of microvascular decompression (MVD) for trigeminal neuralgia (TN) caused by venous conflict remains unclear. The objectives of this study are to characterize the offending veins identified during MVD for TN and to evaluate intraoperative technique applied for their management. From 2007 till 2019, 308 MVD surgeries were performed in 288 consecutive patients with TN, and in 58 of them, pure venous conflict was identified. In 44 patients, the offending vein was interrupted, as was done for small veins arising from the cisternal trigeminal nerve (CN V) or its root entry zone (REZ) causing their stretching (19 cases), small veins on the surface of REZ (9 cases), transverse pontine vein (TPV) compressing REZ or distal CN V (12 cases), and superior petrosal vein (SPV) using flow conversion technique (4 cases). In 14 other cases, the offending vein was relocated, as was done for the SPV or the vein of cerebellopontine fissure (8 cases), TPV (3 cases), and the vein of middle cerebellar peduncle (3 cases). Complete pain relief after surgery was noted in 49 patients (84%). No one patient experienced major neurological deterioration. Postoperative facial numbness developed in 14 patients (24%), and in 8 of them, it was permanent. In 14 patients, MRI demonstrated venous infarction of the middle cerebellar peduncle, which was associated with the presence of any (P = 0.0180) and permanent (P = 0.0002) facial numbness. Ten patients experienced pain recurrence. Thus, 39 patients (67%) sustained complete pain relief at the last follow-up (median, 48 months), which was significantly associated with the presence of any (P = 0.0228) and permanent (P = 0.0427) postoperative facial numbness. In conclusion, in cases of TN, small offending veins arising from REZ and/or distal CN V and causing their stretching may be coagulated and cut. In many cases, TPV can be also interrupted safely or considered as collateral way for blood outflow. The main complication of such procedures is facial numbness, which is associated with the venous infarction of middle cerebellar peduncle and long-term complete pain relief.

Delayed Contralateral Trigeminal Neuralgia After Microvascular Decompression and Postoperative Changes in Venous Outflow

A 66-year-old woman had presented with a 3-month history of left trigeminal neuralgia. She had undergone successful microvascular decompression for right-sided trigeminal neuralgia 8 years previously. To optimize visualization, microvascular decompression for trigeminal neuralgia has been commonly associated with sacrifice of the superior petrosal vein during surgery. The absence of sufficient collaterals can result in most of the posterior fossa venous drainage relying solely on the contralateral superior petrosal vein, leading to subsequent vessel enlargement and a compressive effect on the trigeminal nerve and causing iatrogenic contralateral trigeminal neuralgia. We have provided preoperative and intraoperative images illustrating nicely the adapted postoperative change in venous outflow causing contralateral compression of the trigeminal nerve. Consecutive treatment effects should be carefully considered when offering and performing surgical microvascular decompression.

Prognostic nomogram for microvascular decompression-treated trigeminal neuralgia

This study aimed to establish an effective prognostic nomogram for microvascular decompression (MVD)-treated trigeminal neuralgia (TN). The nomogram was based on a retrospective cohort study of 1054 patients with TN. During the period 2005-2014, 845 patients at our department treated TN with MVD and served as a development cohort. The predictive accuracy and discriminative ability of the nomogram were determined by concordance index (C-index) and calibration curve. The model was externally validated by 209 TN patients during 2014-2016. Multivariate cox analysis suggested that the patient's age, atypical pain, vascular type, number of offending vessels, and second MVD were significant factors influencing the prognosis of MVD-treated TN. The C index of nomogram in the development cohort was 0.767 (95% CI, 0.739-0.794), and 0.749 (95% CI, 0.688-0.810) in the validation cohort. We developed and validated a nomogram to predict 3-year overall remission rate after MVD treatment of TN. The nomogram can be used in clinical trials to determine the likelihood of pain recurrence in TN patients treated with MVD for 3 years to aid in the comprehensive treatment of TN.

Pain Outcomes Following Microvascular Decompression for Drug-Resistant Trigeminal Neuralgia: A Systematic Review and Meta-Analysis

BACKGROUND

Microvascular decompression (MVD) is a potentially curative surgery for drug-resistant trigeminal neuralgia (TN). Predictors of pain freedom after MVD are not fully understood.

OBJECTIVE

To describe rates and predictors for pain freedom following MVD.

METHODS

Using preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, PubMed, Cochrane Library, and Scopus were queried for primary studies examining pain outcomes after MVD for TN published between 1988 and March 2018. Potential biases were assessed for included studies. Pain freedom (ie, Barrow Neurological Institute score of 1) at last follow-up was the primary outcome measure. Variables associated with pain freedom on preliminary analysis underwent formal meta-analysis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for possible predictors.

RESULTS

Outcome data were analyzed for 3897 patients from 46 studies (7 prospective, 39 retrospective). Overall, 76.0% of patients achieved pain freedom after MVD with a mean follow-up of 1.7 ± 1.3 (standard deviation) yr. Predictors of pain freedom on meta-analysis using random effects models included (1) disease duration ≤5 yr (OR = 2.06, 95% CI = 1.08-3.95); (2) arterial compression over venous or other (OR = 3.35, 95% CI = 1.91-5.88); (3) superior cerebellar artery involvement (OR = 2.02, 95% CI = 1.02-4.03), and (4) type 1 Burchiel classification (OR = 2.49, 95% CI = 1.32-4.67).

CONCLUSION

Approximately three-quarters of patients with drug-resistant TN achieve pain freedom after MVD. Shorter disease duration, arterial compression, and type 1 Burchiel classification may predict more favorable outcome. These results may improve patient selection and provider expectations.

Bridging veins and veins of the brainstem in microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm

OBJECTIVE In microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm, the bridging veins are dissected to provide the surgical corridors, and the veins of the brainstem may be mobilized in cases of venous compression. Strategy and technique in dissecting these veins may affect the surgical outcome. The authors investigated solutions for minimizing venous complications and reviewed the outcome for venous decompression. METHODS The authors retrospectively reviewed their surgical series of microvascular decompression for trigeminal neuralgia and hemifacial spasm in patients treated between 2005 and 2017. Surgical strategies included preservation of the superior petrosal vein and its tributaries, thorough dissection of the arachnoid sleeve that enveloped these veins, cutting of the inferior petrosal vein over the lower cranial nerves, and mobilization or cutting of the veins of the brainstem that compressed the nerve roots. The authors summarized the patient characteristics, operative findings, and postoperative outcomes according to the vascular compression types as follows: artery alone, artery and vein, and vein alone. They analyzed the data using chi-square and 1-way ANOVA tests. RESULTS The cohort was composed of 121 patients with trigeminal neuralgia and 205 patients with hemifacial spasm. The superior petrosal vein and its tributaries were preserved with no serious complications in all patients with trigeminal neuralgia. Venous compression alone and arterial and venous compressions were observed in 4% and 22%, respectively, of the patients with trigeminal neuralgia, and in 1% and 2%, respectively, of those with hemifacial spasm (p < 0.0001). In patients with trigeminal neuralgia, 35% of those with artery and venous compressions and 80% of those with venous compression alone had atypical neuralgia (p = 0.015). The surgical cure and recurrence rates of trigeminal neuralgias with venous compression were 60% and 20%, respectively, and with arterial and venous compressions the rates were 92% and 12%, respectively (p < 0.0001, p = 0.04). In patients with hemifacial spasm who had arterial and venous compressions, their recurrence rate was 60%, and that was significantly higher compared to other compression types (p = 0.0008). CONCLUSIONS Dissection of the arachnoid sleeve that envelops the superior petrosal vein may help to reduce venous complications in surgery for trigeminal neuralgia. Venous compression may correlate with worse prognosis even with thorough decompression, in both trigeminal neuralgia and hemifacial spasm.

Repeat microvascular decompression for patients with persistent or recurrent trigeminal neuralgia: Prognostic factors and long-term outcomes

Patients with persistent or recurrent trigeminal neuralgia (TN) after microvascular decompression (MVD) are frequently difficult to manage. This study aimed to analyze the safety and efficiency of repeat MVD, with the main focus on prognostic factors and long-term outcomes.We performed a retrospective study of 41 TN patients (19 men, 22 women) who underwent repeat MVD due to persistent or recurrent pain from January 2008 to January 2016. These patients were followed up from 12 to 96 months (mean, 42 ± 17.3 months). Univariate analysis by Spearman's rank correlation coefficient was used for analysis of prognostic factors.During the repeat MVD, compression of the trigeminal nerve was noted by an artery in 15 patients (36.6%), vein in 6 patients (14.6%), Teflon in 8 patients (19.5%), and no compression in 12 patients (29.3%). Twenty-one patients (51.2%) had already undergone 1 or more previous ablative procedures, either before the first MVD or between the surgeries. The complete pain relief rates of repeat MVD were 87.8% immediately after surgery and 75% at last follow-up. Thirteen patients (31.7%) had new or increased facial numbness after repeat surgery. Univariate analysis revealed 2 prognostic factors, negative finding during reoperation (P = .021) and no pain relief after the initial surgery (P = .038), that showed a negative influence on success rates after repeat MVD.Repeat MVD can still achieve an excellent outcome in patients with persistent or recurrent pain. However, the risk of facial numbness is increased. Surgeons should be selective in performing repeat MVD, priority should be given to patients who have a pain-free interval after initial MVD or show demonstrable compression on imaging studies.

Endoscope-Assisted Microneurosurgery for Neurovascular Compression Syndromes: Basic Principles, Methodology, and Technical Notes

Background:

Microscopic microvascular decompression (MVD) has a low but not negligible failure rate due to some missed conflicts, especially in case of multiple offending vessels. The reported study is aimed to assess the principles, methodology, technical notes, and effectiveness of the endoscope-assisted (EA) MVD for neurovascular compression syndromes (NVCS) in the posterior fossa.

Materials and Methods:

A series of 43 patients suffering from an NVCS and undergone to an EA MVD were retrospectively reviewed. Syndromes were trigeminal neuralgia in 25 cases, hemifacial spasm in nine cases, positional vertigo in six cases, glossopharyngeal neuralgia in two cases, and spasmodic torticollis in one case. In all cases, a 0°–30° specially designed endoscope was inserted into the surgical field to find/treat those conflicts missed by the microscopic exploration. Each procedure was judged in terms of the effectiveness of the adjunct of the endoscope according to a three types classification system: Type I – improvement in the visualization of the nerve's root entry/exit zone; Type II – endoscopic detection of one or more conflicts involving the ventral aspects of the nerve and missed by the microscope; Type III – endoscope-controlled release of the neurovascular conflict otherwise difficult to treat under the only microscopic view.

Results:

A total of 55 conflicts were found and treated. Twenty-eight procedures were classified as Type I, nine as Type II, and six as Type III. All the patients had a full recovery from their symptoms.

Conclusions:

In selected cases, EA MVD offers some advantages in the detection and treatment of neurovascular conflicts in the posterior fossa.

Contrast-Enhanced CISS Imaging for Evaluation of Neurovascular Compression in Trigeminal Neuralgia: Improved Correlation with Symptoms and Prediction of Surgical Outcomes

BACKGROUND AND PURPOSE

Thin-section MR imaging through the posterior fossa is frequently used for trigeminal neuralgia. Typical heavily T2-weighted imaging methods yield high anatomic detail and contrast between CSF and neurovascular structures, but poor contrast between vessels and nerves. We hypothesized that the addition of gadolinium-based contrast material to 3D-constructive interference in steady-state imaging would improve the characterization of trigeminal compression.

MATERIALS AND METHODS

Retrospective review of high-resolution MRIs was performed in patients without prior microvascular decompression. 3D-CISS imaging without contrast and with contrast for 81 patients with trigeminal neuralgia and 15 controls was intermixed and independently reviewed in a blinded fashion. Cisternal segments of both trigeminal nerves were assessed for the grade of neurovascular conflict, cross-sectional area, and degree of flattening. Data were correlated with symptom side and pain relief after microvascular decompression using the Fisher exact test, receiver operating curve analysis, and a paired t test.

RESULTS

Contrast-enhanced CISS more than doubled the prevalence of the highest grade of neurovascular conflict (14.8% versus 33.3%, P = .001) and yielded significantly lower cross-sectional area (P = 8.6 × 10^-6) and greater degree of flattening (P = .02) for advanced-grade neurovascular conflict on the symptoms side compared with non-contrast-enhanced CISS. Patients with complete pain relief after microvascular decompression had significantly lower cross-sectional area on contrast-enhanced CISS compared with non-contrast-enhanced CISS on preoperative imaging (P = 2.0 × 10^-7). Performance based on receiver operating curve analysis was significantly improved for contrast-enhanced CISS compared with non-contrast-enhanced CISS.

CONCLUSIONS

The addition of contrast material to 3D-CISS imaging improves the performance of identifying unilateral neurovascular compression for symptomatic trigeminal neuralgia and predicting outcomes after microvascular decompression.

Prospective Comparison of Redo Microvascular Decompression and Percutaneous Balloon Compression as Primary Surgery for Recurrent Trigeminal Neuralgia

OBJECTIVE

To prospectively compare facial pain outcomes for patients having either a repeat microvascular decompression (MVD) or percutaneous balloon compression (PBC) as their surgery for trigeminal neuralgia (TN) recurrence.

METHODS

Prospective cohort study of 110 patients with TN recurrence who had either redo MVD (n=68) or PBC (n=42) from July 2010 until September 2016. The mean follow-up was 45.6 months.

RESULTS

After redo MVD, 65 patients (95.6%) experienced immediate relief of pain. After PBC, 34 patients (81%) were immediately relieved of their neuralgia. After 1 month, the clinical effect of redo MVD was better than PBC (p<0.01). Patients who had redo MVD more commonly were pain free off medications (93.4% at 1 year, 78.2% at 4 years) compared with the PBC patients (85.1% at 1 year, 59.3% at 4 years). However, mean length of stay was longer (p>0.05). Patients after PBC who occurred developed herpes simplex (35.7%), facial numbness (76.2%), annoying dysesthesia (21.4%) more frequently compared with patients after redo MVD who occurred developed herpes simplex (14.7%), facial numbness (8.8%), hypoesthesia (5.9%) (p<0.05). The symptoms recurred respectively in 15 patients (22.1%) and 19 patients (45.2%) after redo MVD and PBC within the entire 6-year follow-up period.

CONCLUSION

For the patients with TN recurrence, redo MVD was a more effective procedure than PBC. The cure rate and immediate relief of pain were better, and the incidence of complications was lower.

Management of veins during microvascular decompression for idiopathic trigeminal neuralgia

OBJECT

To summarize our experience in treating veins during microvascular decompression (MVD) procedures for idiopathic trigeminal neuralgia (TN).

METHODS

A total of 210 patients who underwent single MVD for idiopathic TN were retrospectively studied. The offending vessels were summarized. The treatment choices for veins during the operation were reviewed. Postoperative long-term outcomes were determined by follow-up.

RESULTS

Veins accounted for 26.7% of the total 262 offending vessels. Neurovascular conflicts were caused by veins alone in 23 patients (11.2%), and they were caused by arteries and veins together in 47 patients (22.8%). The offending veins were cut (15.7%) or saved (84.3%) during the operation. Excellent long-term outcomes were acquired in 78.3% of the patients with venous type TN.

CONCLUSION

There are no acknowledged principles guiding the treatment of veins during MVD. Our primary treatment principle is to retain veins as often as possible.

The Multiscope Technique for Microvascular Decompression

BACKGROUND

Endoscopic surgery has rapidly become widespread in neurosurgery in recent years. Endoscopy can offer close and panoramic surgical views with fine illumination, even in the deep intracranial area. However, it also has the following serious drawback: an intracranial blind area between the field lens of the endoscope and the site of the dural opening. This blind area cannot be viewed on the endoscopic monitor, and several surgical complications, including accidental intracranial neurovascular structural injury, can occur in this area. In this article, we report a new multiscope surgical technique that can compensate for this serious disadvantage of endoscopic surgery.

METHODS

In the multiscope technique, endoscopic and exoscopic systems are used simultaneously with 2 monitors. Microvascular decompression (MVD) is performed fully endoscopically using an exoscope that compensates for the intracranial blind area of the endoscopic view. Two high-definition monitors for the endoscope and exoscope are placed side-by-side in front of the primary surgeon.

RESULTS

Two patients with hemifacial spasm were treated by endoscopic MVD with the multiscope technique. In these procedures, fine surgical views were obtained by both the endoscope and exoscope. Two monitors were placed side-by-side in front of the surgeon; as a result, the physician could easily view them simultaneously during the operation. No surgery-related complications occurred.

CONCLUSIONS

The multiscope technique can facilitate the performance of safer neuroendoscopic surgery than conventional endoscopic surgery. This technique can also be adopted in other skull base surgeries, in which the importance of endoscopy is growing.

Diagnosis and management for trigeminal neuralgia caused solely by venous compression

BACKGROUND

Trigeminal neuralgia (TN) caused solely by venous compression is uncommon. An appropriate vein management protocol for microvascular decompression (MVD) has not been established. We evaluated the management of veins for TN solely due to venous involvement.

METHOD

We analyzed 31 patients with TN in whom only veins were manipulated during MVD. The culprit veins smaller in diameter than the vein of the cerebellopontine fissure (VCPF) were coagulated and divided in 20 patients (divided group), while transposition was performed for larger veins in the remaining 11 patients (non-divided group). Postoperative outcomes were assessed by Barrow Neurological Institute (BNI) pain intensity score and BNI facial numbness score.

RESULTS

Preoperative contrast-enhanced T1 spoiled gradient recalled (SPGR) imaging exhibited higher detection rates for veins (93.5%) than non-contrast fast imaging employing a steady-state acquisition image (74.2%). The transverse pontine vein (TPV) was the most frequently involved vessel. All the divided veins were small TPVs except one. The non-divided group included seven cases of large TPVs and four involving the main trunk of the superior petrosal vein or its large tributaries. The median follow-up duration was 33 months. Pain relief was achieved immediately after the surgery in 28 (90.3%) and within a month in the remaining 3 (9.7%) patients. Numbness was present in seven (22.6%) patients at the final follow-up. Recurrence was observed in only two (10.0%) patients in the divided group compared with four (36.4%) patients in the non-divided group. Comparison at the final follow-up revealed that the divided group had superior outcome compared to the non-divided group.

CONCLUSIONS

Contrast-enhanced T1 SPGR imaging is crucial to detect small veins in the preoperative diagnosis. Division of the culprit veins is recommended if the diameter is smaller than the VCPF as it provides a better outcome and lower recurrence rate than transposition.

[Surgical management of venous compression causing trigeminal neuralgia]

Venous compression is a rare cause of trigeminal neuralgia (TN). Vascular decompression of the trigeminal nerve root, as the only etiopathogenetic treatment of trigeminal neuralgia, is a well-known procedure that is extensively used at various neurosurgical clinics. As the number of interventions for TN increases, the absolute number of surgeries for eliminating venous compression of the trigeminal nerve also grows. Five hundred TN patients underwent surgery at the Neurosurgical Institute in the period from 2000 to 2015. The diagnosis was made based on the criteria of the International Classification of Headache Disorders, the 3rd edition, (ICHD-3) and the Burchiel classification. The study included 211 males and 289 females. The median age was 57 years. All patients had typical TN pain with a unilateral distribution. Two or more branches were affected in 90 patients; one branch was predominantly affected in 10 patients. The median disease duration was 16 months. The median visual analog scale (VAS) score was 8 (very severe persistent pain). In all cases, the patients underwent surgery using the retrosigmoid suboccipital approach. The median postoperative follow-up was 36 months. The aim of this work is to summarize the first experience of the Neurosurgical Institute in surgical treatment for venous compression of the Vth nerve root and suggest methods increasing the efficacy of vascular decompression in patients with this disease.

Management of different kinds of veins during microvascular decompression for trigeminal neuralgia: technique notes

OBJECTIVE

During microvascular decompression surgery for trigeminal neuralgia, surgeons will encounter various kinds of veins that block the approach to or compress the trigeminal nerve. The aim of this study was to present our experience in managing different kinds of veins.

METHODS

This was a retrospective study of 21 patients with trigeminal neuralgia, in whom one or more veins were encountered during surgery. The techniques used in treating 4 types of veins during microvascular decompression were assessed, and the surgical outcomes and operative complications were analysed.

RESULTS

For the first type, large veins blocking the approach towards the root entry zone (REZ) of the trigeminal nerve were bypassed via cerebellar fissure approach. Second, veins lying on the brainstem surface and compressing the REZ were detached using a gelatin-assisted dissecting technique and then interposed. Third, veins rising from the surface of the brainstem and crossing the cisternal portion of the trigeminal nerve were interposed. Fourth, intraneural veins, which were generally small, were coagulated and cut. In this series, there was no intentional sacrifice or unintentional rupture of large veins, and the sacrifice rate of medium and small veins was only 19.0%. Thirteen patients (61.9%) gained complete pain relief immediately after surgery (i.e. "excellent" result), while the remaining eight patients (38.1%) achieved "good" pain relief.

CONCLUSION

Different surgical techniques were used based on the different kinds of veins encountered. This allowed preservation of almost all the large veins. There were no serious complications postoperatively.

Efficacy of primary microvascular decompression versus subsequent microvascular decompression for trigeminal neuralgia

OBJECTIVE Trigeminal neuralgia (TN) is characterized by intermittent, paroxysmal, and lancinating pain along the distribution of the trigeminal nerve. Microvascular decompression (MVD) directly addresses compression of the trigeminal nerve. The purpose of this study was to determine whether patients undergoing MVD as their first surgical intervention experience greater pain control than patients who undergo subsequent MVD. METHODS A retrospective review of patient records from 1998 to 2015 identified a total of 942 patients with TN and 500 patients who underwent MVD. After excluding several cases, 306 patients underwent MVD as their first surgical intervention and 175 patients underwent subsequent MVD. Demographics and clinicopathological data and outcomes were obtained for analysis. RESULTS In patients who underwent subsequent MVD, surgical intervention was performed at an older age (55.22 vs 49.98 years old, p < 0.0001) and the duration of symptoms was greater (7.22 vs 4.45 years, p < 0.0001) than for patients in whom MVD was their first surgical intervention. Patients who underwent initial MVD had improved pain relief and no improvement in pain rates compared with those who had subsequent MVD (95.8% and 4.2% vs 90.3% and 9.7%, respectively, p = 0.0041). Patients who underwent initial MVD had significantly lower rates of facial numbness in the pre- and postoperative periods compared with patients who underwent subsequent MVD (p < 0.0001). The number of complications in both groups was similar (p = 0.4572). CONCLUSIONS The results demonstrate that patients who underwent other procedures prior to MVD had less pain relief and a higher incidence of facial numbness despite rates of complications similar to patients who underwent MVD as their first surgical intervention.

Venous compression as a cause of trigeminal neuralgia

AIM

The study objective was to verify venous compression as a cause of trigeminal neuralgia (TN) and to define the optimal surgical tactics for TN patients.

MATERIAL AND METHODS

Four hundred twenty one patients were operated on for TN at the Neurosurgical Department of the City Hospital №2 from 1998 to 2015. Veins in the trigeminal nerve root entry zone, as a significant compression factor, were identified in 40 patients (9.5%). Intraoperative data, questionnaires, and self-assessment inventories were analyzed. Treatment outcomes were assessed using the Barrow Neurological Institute (BNI) scale.

RESULTS

Patients with venous compression were divided into two groups. Eleven (27.5%) patients in the first group had isolated venous compression. The feature of microvascular decompression (MVD) in these patients was identification of all veins, vein mobilization, and, if possible, vein coagulation and resection. Resection of the vein along its course is a basic procedure to avoid recurrent neuralgia. The second group included 29 (72.5%) patients with a combination of venous and arterial compression. In these patients, a vein acted as an "assisting" compression factor: the vein changed the course of a compressing artery or nerve and exerted an additional compression effect on the nerve. The surgical tactics involved exploration of the trigeminal nerve root entry zone, arterial loop mobilization, and placement of a Teflon protector; venous vessels were coagulated and resected. The MVD efficacy was as follows: in group 1, 10 patients had a BNI score I-III, and 1 patient had a BNI score IV; in group II, 25 patients had a BNI score I-III, and 4 patients had a BNI score IV.

CONCLUSION

Venous compression can play both independent and assisting roles in the TN genesis. When exploring the trigeminal nerve, examination of the proximal trigeminal nerve is of particular importance, with paying attention to veins that may be a compression factor. In the case of isolated venous compression, the MVD surgical technique has some peculiarities, in particular coagulation and resection of veins compressing the trigeminal nerve root entry zone.

Clinical characteristics and surgical techniques of trigeminal neuralgia caused simply by venous compression

OBJECTIVE

The objective of this study was to introduce the operation essentials for treatment of patients with vein compression so as to obtain a satisfactory decompression without sacrificing veins.

METHODS

We chose 15 patients with trigeminal neuralgia caused by venous from June 15, 2010, through June 15, 2011, and performed microvascular decompression for each patient. By collecting clinical data, such as preoperative magnetic resonance imaging scans, key operative procedures, surgical outcomes, and complications, we explored the operation techniques for these patients and finally summarized our experiences and ideas.

RESULTS

For all the 15 patients, 9 cases had excellent remission, 3 cases had delayed excellent remission, 1 case had good remission, and 2 cases had failed result; the total remission rate was 86.7%; 3 cases had facial numbness.

CONCLUSIONS

For patients with vein compression, we combine the following 4 procedures together: (1) fully releasing the arachnoid around trigeminal nerve, (2) exploration and decompression of the whole trigeminal root from Meckel cave to pons, (3) cauterization of companioned petrosal vein tributaries by bipolar coagulation, and (4) placing Teflon between trigeminal nerve and offending petrosal vein, thus could acquire a satisfactory effect (remission rate, 86.7%).

CT-Guided Percutaneous Radiofrequency Thermocoagulation for Recurrent Trigeminal Neuralgia After Microvascular Decompression: A Cohort Study

This article evaluates the long-term outcomes of computed tomography (CT)-guided percutaneous radiofrequency thermocoagulation (PRT) for patients with recurrent trigeminal neuralgia (TN) after microvascular decompression (MVD).This is a retrospective study of 41 patients with intractable TN who after MVD underwent CT-guided PRT procedures between 2002 and 2012.The mean length of follow-up after PRT was 44.4 months. Immediate pain relief was in 37 patients (90.2%); the percentage of patients who remained in "excellent" or "good" pain relief condition after CT-guided PRT procedure was 85% at 1 year, 80% at 2 years, 51% at 5 years, and 41% at 10 years. Six patients received the second PRT and all achieved "excellent" or "good" pain relief. In total, 34 of these patients (82.9%) received multi-PRT procedure and remained satisfied with their pain relief during the follow-up period. Postoperative complications included facial numbness in 36 patients, limited eyes opening in 1 patient, ear paresthesia in 1 patient, no tears in 1 patient, and taste hypesthesia in 1 patient; these symptoms were all improved in the process of follow-up and their life had not severely affected. No mortality was observed during and after CT-guided PRT procedures.CT-guided PRT should be considered as an alternative treatment for patients with recurrent TN after MVD.

Classification of the superior petrosal veins and sinus based on drainage pattern

BACKGROUND

The increasing number of reports of complications after sacrificing the superior petrosal veins, the largest veins in the posterior fossa, has led to a need for an increased understanding of the anatomy of these veins and the superior petrosal sinus into which they empty.

OBJECTIVE

To examine the anatomy of the superior petrosal veins and their size, draining area, and tributaries, as well as the anatomic variations of the superior petrosal sinus.

METHOD

Injected cadaveric cerebellopontine angles and 3-dimensional multifusion angiography images were examined.

RESULTS

The 4 groups of the superior petrosal veins based on their tributaries, course, and draining areas are the petrosal, posterior mesencephalic, anterior pontomesencephalic, and tentorial groups. The largest group was the petrosal group. Its largest tributary, the vein of the cerebellopontine fissure, was usually identifiable in the suprafloccular cistern located above the flocculus on the lateral surface of the middle cerebellar peduncle. The medial or lateral segment of the superior petrosal sinus was absent in 40% of cerebellopontine angles studied with venography.

CONCLUSION

The superior petrosal veins and their largest tributaries, especially the vein of the cerebellopontine fissure, should be preserved if possible. Obliteration of superior petrosal sinuses in which either the lateral or medial portion is absent may result in loss of the drainage pathway of the superior petrosal veins. Preoperative assessment of the superior petrosal sinus should be considered before transpetrosal surgery in which the superior petrosal sinus may be obliterated.

[Microvascular decompresion for trigeminal neuralgia, report of 36 cases and literature review]

Objetivo:

El propósito del presente trabajo es presentar los resultados de 36 pacientes con diagnóstico de neuralgia del trigémino (NT), en los cuales se realizó una descompresión microvascular (DMV).

Material y Método:

Desde junio de 2005 a mayo de 2012, 36 pacientes con diagnóstico de NT fueron operados por el primer autor (AC), realizando una DMV. Se evaluó: Edad, sexo, tiempo de sintomatología previo a la cirugía, hallazgos intraoperatorios (a través de los videos quirúrgicos), y resultados postoperatorios.

Resultados:

De los 36 pacientes operados, 25 fueron mujeres y 11 varones. El promedio de edad fue de 48 años. El seguimiento postoperatorio fue en promedio de 38 meses. De los 36 pacientes, 32 (88%) evolucionaron sin dolor hasta la fecha. De los 4 casos con recurrencia de dolor, en dos pacientes se observó como hallazgo intraoperatorio un conflicto venoso.

Conclusión:

La DMV como tratamiento de la NT es un procedimiento efectivo y seguro. El hallazgo intraoperatorio de una “compresión” venosa podría indicar una evolución postoperatoria desfavorable.

Usefulness of the endoscope in microvascular decompression for trigeminal neuralgia and MRI-based prediction of the need for endoscopy

BACKGROUND

Microvascular decompression (MVD) is a documented effective treatment of trigeminal neuralgia (TN). Lately, reports on endoscopy-assisted microvascular decompression (eaMVD) with better outcome and less risk have emerged. This study was undertaken to verify under which circumstances the endoscope proved essential in identifying the neurovascular conflict (NVC) during eaMVD for TN, and to assess the possibility to predict the need for the endoscope on preoperative magnetic resonance imaging (MRI).

METHODS

Retrospective analysis of 97 patients with TN undergoing eaMVD at the Oslo University Hospital - Rikshospitalet, 1999-2009. To assess the NVC and anatomical variations, surgical reports were evaluated. MRI was available in 66 patients. The MRIs were evaluated by a blinded neuroradiologist.

RESULTS

In 27 of the 97 patients (27.8 %), the endoscope was a significant aid in identifying the NVC, due to a bony ridge obscuring the view of the fifth nerve, a very distal vascular compression, or a combination of both. The preoperative MRI over-diagnosed the presence of a bony ridge. However, the MRI-based fraction of microscopically visible trigeminal nerve (FVN) in the cerebellopontine angle cistern proved diagnostic (ROC curve, AUC 0.89, p = <0.001) with an optimal cut-off value of 0.35. Hence, if less than 35 % of the trigeminal nerve is visible on preoperative MRI, the endoscope will be needed to identify the NVC.

CONCLUSIONS

The endoscope is a valuable tool during MVD for TN, especially under anatomical circumstances such as a bony ridge hiding the direct microscopic view of the NVC. These anatomical circumstances can be predicted with good accuracy on preoperative MRI.

Trigeminal Neuralgia due to an Isolated Cerebral Varix: Case Report

Intracranial isolated varix is a very rare entity. Although it is usually asymptomatic, there are reports on symptomatic cases with hemorrhage or mass effect that mostly relate to arteriovenous fistulas or arteriovenous malformations. We present an extremely rare case of trigeminal neuralgia caused by an isolated varix. A 55-year-old woman had been experiencing right trigeminal neuralgia for 3 years. Computed tomography and magnetic resonance imaging revealed an enhanced mass lesion on the root entry zone of the right trigeminal nerve. Angiograms confirmed the mass was a varix arising on the vein connecting the basal vein of Rosenthal and the superior petrosal vein. Preoperative three-dimensional (3D) imaging clearly depicted the anatomical relation of the varix, adjacent vessels, and trigeminal nerve, which helped plan operative procedures. The varix with its parent vein was successfully transposed from the nerve without sacrificing any veins. Her pain disappeared immediately after the surgery and did not recur during a 30-month follow-up period. The 3D image contributed to making an accurate and safer operative plan especially for this rare case.

Trigeminal neuralgia occurs and recurs in the absence of neurovascular compression

Object

Vascular compression of the trigeminal nerve is the most common factor associated with the etiology of trigeminal neuralgia (TN). Microvascular decompression (MVD) has proven to be the most successful and durable surgical approach for this disorder. However, not all patients with TN manifest unequivocal neurovascular compression (NVC). Furthermore, over time patients with an initially successful MVD manifest a relentless rate of TN recurrence.

Methods

The authors performed a retrospective review of cases of TN Type 1 (TN1) or Type 2 (TN2) involving patients 18 years or older who underwent evaluation (and surgery when indicated) at Oregon Health & Science University between July 2006 and February 2013. Surgical and imaging findings were correlated.

Results

The review identified a total of 257 patients with TN (219 with TN1 and 38 with TN2) who underwent high-resolution MRI and MR angiography with 3D reconstruction of combined images using OsiriX. Imaging data revealed that the occurrence of TN1 and TN2 without NVC was 28.8% and 18.4%, respectively. A subgroup of 184 patients underwent surgical exploration. Imaging findings were highly correlated with surgical findings, with a sensitivity of 96% for TN1 and TN2 and a specificity of 90% for TN1 and 66% for TN2.

Conclusions

Magnetic resonance imaging detects NVC with a high degree of sensitivity. However, despite a diagnosis of TN1 or TN2, a significant number of patients have no NVC. Trigeminal neuralgia clearly occurs and recurs in the absence of NVC.

Comparison of microscopic and endoscopic approaches to the cerebellopontine angle

OBJECTIVE

To examine the efficacy of the endoscope as an adjunct to the operating microscope in defining the surgical anatomy of the cerebellopontine angle (CPA).

METHODS

The surgical anatomy of the CPA was examined in cadaveric CPAs through a retrosigmoid approach. The upper, middle, and lower neurovascular complexes and the individual segments of the cerebellar arteries in the CPA were examined with the surgical microscope and 0° and 45° rigid endoscopes.

RESULTS

The microscope provided satisfactory views of the posterior surface of the neural and vascular structures in the central part of the CPA cistern. The endoscope provided superior views of the nerves' junction with the brainstem, their dural exit, and their vascular relationships. The endoscope also provided superior views of the individual segments of the cerebellar arteries.

CONCLUSION

The combination of endoscopic and microsurgical techniques aids in achieving optimal exposure in CPA surgery.

Outcome of microvascular decompression for trigeminal neuralgia using autologous muscle graft: A five-year prospective study

Introduction:

Trigeminal Neuralgia (TGN) is a syndrome characterized by Paroxysmal, shock like hemifacial pain. Among the various treatment options micro vascular decompression (MVD) has gained popularity in the recent years.

Materials and Methods:

182 patients underwent MVD, between 1995–2007 out of 530 patients treated for Trigeminal Neuralgia at our service. All were operated by retro auricular sub occipital craniectomy by a single surgeon using autologous muscle graft. They were assessed for pain relief, complications and the data was analysed.

Results:

Males were 84 (61.3%) females 53 (38%) with a ratio of 1.5=1. Age ranged from 25-75 years. Duration of symptoms ranging from 6 months to 25 years (average 4-6 years). Seventy seven (56.2% were affected on the right side whereas 60 (43.8%) had pain on the left side. Imaging demonstrated vascular compression in 84 (61%). At surgery superior cerebellar artery was the commonest cause of compression in 71.5%. More than one artery was found in relation to the nerve in 15.3%. There was no mortality, CSF leak 2.9% and transient facial palsy in 2.2% were the notable complications.

Conclusion:

MVD is the procedure of choice for TGN if there is no contraindication for surgery. Adequate tissue respect, meticulous surgical steps and experience will reduce complications. Autologus muscle graft can give comparable and durable results possibly with lesser complications.

Endoscope-assisted neurovascular decompression of the trigeminal nerve: a cadaveric study

Endoscopes are increasingly used to examine cranial nerves in microvascular decompression (MVD) operations. The superior petrosal vein (SPV) is often purposely sacrificed to gain adequate exposure to the trigeminal nerve (TN) during MVD. Recently, the importance of preserving the SPV has been emphasized due to potential complications associated with its sacrifice. Our focus is to study the ability to operate on the TN with preservation of the SPV by using endoscope-assisted microsurgery. We studied both cerebellopontine angles in seven cadaveric heads which vascular system had been injected with colored silicon material. MVD procedures were simulated using the operative microscope (Moeller-Wedel, Cologne, Germany) and two fixed-angled (0°and 30°) rigid endoscopes (Aesculap, PA, USA). To compare the practical advantages of microscopic MVD (MMVD) and endoscope-assisted MVD (EAMVD), we divided the approaches into four subcategories (microscopic without and with SPV sacrifice and endoscope-assisted without and with SPV sacrifice) and compared the maneuverability associated with each category using a numerical grading system. EAMVD scored significantly better than MMVD both without and with cutting of the SPV (p < 0.001). Only in MMVD did cutting of the SPV improve the maneuverability especially in the superior quadrant of the nerve (p = 0.012). Based on the proposed scoring system, use of the endoscope in an assisted mode facilitates visualization and mobilization of the vascular loop associated with the TN without need to sacrifice the SPV. Sacrifice of the SVP may help maneuverability in the superior quadrant of the nerve in MMVD.