Tag: Trigeminal neuralgia

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Sex-dependent posterior fossa anatomical differences in trigeminal neuralgia patients with and without neurovascular compression: a volumetric MRI age- and sex-matched case-control study

J Neurosurg 132:631–638, 2020

The pathophysiology of trigeminal neuralgia (TN) in patients without neurovascular compression (NVC) is not completely understood. The objective of this retrospective study was to evaluate the hypothesis that TN patients without NVC differ from TN patient with NVC with respect to brain anatomy and demographic characteristics.

METHODS Six anatomical brain measurements from high-resolution brain MR images were tabulated; anterior-posterior (AP) prepontine cistern length, cerebellopontine angle (CPA) cistern volume, nerve-to-nerve distance, symptomatic nerve length, pons volume, and posterior fossa volume were assessed on OsiriX. Brain MRI anatomical measurements from 232 patients with either TN type 1 or TN type 2 (TN group) were compared with measurements obtained in 100 age- and sex-matched healthy controls (control group). Two-way ANOVA tests were conducted on the 6 measurements relative to group and NVC status. Bonferroni adjustments were used to correct for multiple comparisons. A nonhierarchical k-means cluster analysis was performed on the TN group using age and posterior fossa volume as independent variables.

RESULTS Within the TN group, females were found to be younger than males and less likely to have NVC. The odds ratio (OR) of females not having NVC compared to males was 2.7 (95% CI 1.3–5.5, p = 0.017). Patients younger than 30 years were much less likely to have NVC compared to older patients (OR 4.9, 95% CI 1.3–18.4, p = 0.017). The mean AP prepontine cistern length and symptomatic nerve length were smaller in the TN group than in the control group (5.3 vs 6.5 mm and 8.7 vs 9.7 mm, respectively; p < 0.001). The posterior fossa volume was significantly smaller in TN patients without NVC compared to those with NVC. A TN group cluster analysis suggested a sex-dependent difference that was not observed in those without NVC. Factorial ANOVA and post hoc testing found that findings in males without NVC were significantly different from those in controls or male TN patients with NVC and similar to those in females (female controls as well as female TN patients with or without NVC).

CONCLUSIONS Posterior fossa volume in males was larger than posterior fossa volume in females. This finding, along with the higher incidence of TN in females, suggests that smaller posterior fossa volume might be an independent factor in the pathophysiology of TN, which warrants further study.

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

Neurosurgery, Volume 86, Issue 2, February 2020, Pages 182–190

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 afterMVD with amean follow-up of 1.7 ± 1.3 (standard deviation) yr. Predictors of pain freedom on meta-analysis using random effectsmodels 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.

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Individual variations of the superior petrosal vein complex and their microsurgical relevance in 50 cases of trigeminal microvascular decompression

Acta Neurochirurgica (2020) 162:197–209

We investigated the understudied anatomical variations of the superior petrosal vein (SPV) complex (SPVC), which may play some role in dictating the individual complication risk following SPVC injury.

Methods Microvascular decompressions of the trigeminal nerve between September 2012 and July 2016. All operations utilized an SPVC preserving technique. Preoperative balanced fast field echo (bFFE) magnetic resonance imaging, or equivalent sequences, and operative videos were studied for individual SPVC anatomical features.

Results Applied imaging and operative SPVC anatomy were described for fifty patients (mean age, 67.18 years; female sex and right-sided operations, 58% each). An SPVC component was sacrificed intentionally in 6 and unintentionally in only 7 cases. Twenty-nine different individual variations were observed; 80% of SPVCs had either 2 SPVs with 3 or 1 SPV with 2, 3, or 4 direct tributaries. Most SPVCs had 1 SPV (64%) and 2 SPVs (32%). The SPV drainage point into the superior petrosal sinus was predominantly between the internal auditory meatus and Meckel cave (85.7% of cases). The vein of the cerebellopontine fissure was the most frequent direct tributary (86%), followed by the pontotrigeminal vein in 80% of SPVCs. Petrosal-galenic anastomosis was detected in at least 38%of cases. At least 1 SPVin 54%of the cases and at least 1 direct tributary in 90%disturbed the operative field. The tributaries were more commonly sacrificed.

Conclusions The extensive anatomical variation of SPVC is depicted. Most SPVCs fall into 4 common general configurations and can usually be preserved. BFFE or equivalent sequences remarkably facilitated the intraoperative understanding of the individual SPVC in most cases.

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Gamma Knife Radiosurgery for Multiple Sclerosis-Associated Trigeminal Neuralgia

 

Neurosurgery 85:E933–E939, 2019

Trigeminal neuralgia in the setting of multiple sclerosis (MS-TN) is a challenging condition to manage that is commonly treated with Gamma Knife radiosurgery (GKRS; Elekta AB). However, data regarding the efficacy of this treatment are somewhat limited, particularly for repeat GKRS.

OBJECTIVE: To report outcomes of GKRS for MS-TN from a cohort study.

METHODS: Retrospective review of our GKRS database identified 77 cases of unilateral MS-TN (UMSTN) in 74 patients treated with GKRS between 2001 and 2016, with 37 cases undergoing repeat GKRS. Background medical history, treatment outcomes and complications, and dosimetric data were obtained by retrospective chart reviews and telephone interviews.

RESULTS:Eighty two percent of UMSTN cases achieved Barrow Neurological Institute (BNI) IIIb or better pain relief following initial GKRS for a median duration of 1.1 yr. Estimated rates ofpainreliefat1,3,and5yr were 51,39,and29% respectively.Eighty-eightpercentachieved BNI IIIb or better pain relief after repeat GKRS for a median duration of 4.0 yr. Estimated rates of pain relief at 1 and 3 yr were 70 and 54%, respectively. Median doses for initial and repeat GKRS were 85 and 80 Gy to the 100% isodose line, respectively. Those with MS-TN had a shorter duration of BNI IIIb or better pain relief after initial (4.6 vs 1.1 yr), but not repeat GKRS (3.8 vs 4.0 yr) compared to a historical cohort from our institution.

CONCLUSION: GKRS is an effective, well-tolerated treatment for patientswith MS-TN. More durable relief is often achieved with repeat GKRS.

 

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Repeat Gamma Knife radiosurgery versus microvascular decompression following failure of GKRS in trigeminal neuralgia: a systematic review and meta-analysis

J Neurosurg 131:1197–1206, 2019

Gamma Knife radiosurgery (GKRS) has emerged as a promising treatment modality for patients with classical trigeminal neuralgia (TN); however, considering that almost half of the patients experience post-GKRS failure or lesion recurrence, a repeat treatment is typically necessary. The existing literature does not offer clear evidence to establish which treatment modality, repeat GKRS or microvascular decompression (MVD), is superior. The present study aimed to compare the overall outcome of patients who have undergone either repeat GKRS or MVD after failure of their primary GKRS; the authors do so by conducting a systematic review and meta-analysis of the literature and analysis of data from their own institution.

METHODS The authors conducted a systematic review and meta-analysis of the PubMed, Cochrane Library, Web of Science, and CINAHL databases to identify studies describing patients who underwent either repeat GKRS or MVD after initial failed GKRS for TN. The primary outcomes were complete pain relief (CPR) and adequate pain relief (APR) at 1 year. The secondary outcomes were rate of postoperative facial numbness and the retreatment rate. The pooled data were analyzed with R software. Bias and heterogeneity were assessed using funnel plots and I 2 tests, respectively. A retrospective analysis of a series of patients treated by the authors who underwent repeat GKRS or MVD after postGKRS failure or relapse is presented.

RESULTS A total of 22 studies met the selection criteria and were included for final data retrieval and meta-analysis. The search did not identify any study that had directly compared outcomes between patients who had undergone repeat GKRS versus those who had undergone MVD. Therefore, the authors’ final analysis included two groups: studies describing outcome after repeat GKRS (n = 17) and studies describing outcome after MVD (n = 5). The authors’ institutional study was the only study with direct comparison of the two cohorts. The pooled estimates of primary outcomes were APR in 83% of patients who underwent repeat GKRS and 88% of those who underwent MVD (p = 0.49), and CPR in 46% of patients who underwent repeat GKRS and 72% of those who underwent MVD (p = 0.02). The pooled estimates of secondary outcomes were facial numbness in 32% of patients who underwent repeat GKRS and 22% of those who underwent MVD (p = 0.11); the retreatment rate was 19% in patients who underwent repeat GKRS and 13% in those who underwent MVD (p = 0.74). The authors’ institutional study included 42 patients (repeat GKRS in 15 and MVD in 27), and the outcomes 1 year after retreatment were APR in 80% of those who underwent repeat GKRS and 81% in those who underwent MVD (p = 1.0); CPR was achieved in 47% of those who underwent repeat GKRS and 44% in those who underwent MVD (p = 1.0). There was no difference in the rate of postoperative facial numbness or retreatment.

CONCLUSIONS The current meta-analysis failed to identify any superiority of one treatment over the other with comparable outcomes in terms of APR, postoperative facial numbness, and retreatment rates. However, MVD was shown to provide a better chance of CPR compared with repeat GKRS.

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The Effectiveness of Percutaneous Balloon Compression, Thermocoagulation, and Glycerol Rhizolysis for Trigeminal Neuralgia in Multiple Sclerosis

Neurosurgery 85:E684–E692, 2019

Balloon compression (BC),thermocoagulation (TC),and glycerol rhizolysis (GR) are percutaneous surgical options for trigeminal neuralgia (TN). Whether the outcomes of these procedures in multiple sclerosis-related TN (MS-TN) are as effective as in idiopathic TN (ITN) is unknown.

OBJECTIVE: To retrospectively compare pain relief, complications, and durability achieved by these 3 types of procedures in MS-TN and ITN.

METHODS: Two hundred and four patients with typical TN were treated percutaneously: 33 had MS-TN (64 procedures) and 171 had ITN (329 procedures). All were performed by 1 of 2 neurosurgeons; interviews enabled long-term data to be gathered by an independent observer.

RESULTS: MS-TN patients (53.1%) had Barrow Neurological Institute pain scores of I or II after a percutaneous procedure, compared with 59.3% in the ITN cohort; there was no difference in initial relief between the 2 groups overall (P = .52). There was a trend toward fewer complications in MS-TN compared with ITN (23.4% vs 33.7%, respectively; P = .058). Kaplan–Meier analysis demonstrated no difference in durability of relief in MS-TN (median 23.0 mo) compared with ITN overall (median 24.0 mo; P = .75). Subgroup analysis demonstrated longer relief from BC and TC compared with GR in MS-TN (P = .013). Multivariate analysis confirmed that although the presence of MS does not predict durability of outcome, postoperative numbness (P = .0046) and undergoing a repeat procedure (P = .037) were significant predictors.

CONCLUSION: BC and TC are safe and effective in MS-TN. Postoperative numbness is the strongest prognostic factor in MS-TN.

 

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Early postsurgical diffusivity metrics for prognostication of long-term pain relief after Gamma Knife radiosurgery for trigeminal neuralgia

J Neurosurg 131:539–548, 2019

Gamma Knife radiosurgery (GKRS) is an important treatment modality for trigeminal neuralgia (TN). Current longitudinal assessment after GKRS relies primarily on clinical diagnostic measures, which are highly limited in the prediction of long-term clinical benefit. An objective, noninvasive, predictive tool would be of great utility to advance the clinical management of patients. Using diffusion tensor imaging (DTI), the authors’ aim was to determine whether early (6 months post-GKRS) target diffusivity metrics can be used to prognosticate long-term pain relief in patients with TN.

METHODS Thirty-seven patients with TN treated with GKRS underwent 3T MRI scans at 6 months posttreatment. Diffusivity metrics of fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity were extracted bilaterally from the radiosurgical target of the affected trigeminal nerve and its contralateral, unaffected nerve. Early (6 months post-GKRS) diffusivity metrics were compared with long-term clinical outcome. Patients were identified as long-term responders if they achieved at least 75% reduction in preoperative pain for 12 months or longer following GKRS.

RESULTS Trigeminal nerve diffusivity at 6 months post-GKRS was predictive of long-term clinical effectiveness, where long-term responders (n = 19) showed significantly lower fractional anisotropy at the radiosurgical target of their affected nerve compared to their contralateral, unaffected nerve and to nonresponders. Radial diffusivity and mean diffusivity, correlates of myelin alterations and inflammation, were also significantly higher in the affected nerve of long-term responders compared to their unaffected nerve. Nonresponders (n = 18) did not exhibit any characteristic diffusivity changes after GKRS.

CONCLUSIONS The authors demonstrate that early postsurgical target diffusivity metrics have a translational, clinical value and permit prediction of long-term pain relief in patients with TN treated with GKRS. Importantly, an association was found between the footprint of radiation and clinical effectiveness, where a sufficient level of microstructural change at the radiosurgical target is necessary for long-lasting pain relief. DTI can provide prognostic information that supplements clinical measures, and thus may better guide the postoperative assessment and clinical decision-making for patients with TN.

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Arachnoiditis as an outcome factor for microvascular decompression in classical trigeminal neuralgia

Acta Neurochirurgica (2019) 161:1589–1598

Neurovascular conflict is considered a key element of classical trigeminal neuralgia (TN) and consequently, mi- crovascular decompression (MVD) is an effective treatment. Nevertheless, failures of MVD are described by many authors. In some patients, the arachnoid membranes surrounding the trigeminal nerve and neighbouring vessels may be thickened and adhesive. Here we analyse the impact of such focal arachnoiditis on outcome after MVD for TN.

Methods A cohort of prospectively followed patients after their MVD was reviewed for intraoperative, imaging and clinical data if findings of arachnoiditis during MVD were described. Long-term outcome assessment was the main endpoint.

Results We reviewed data from 395 MVD procedures, performed for TN from 2001 to 2014. Intraoperative evidence of focal arachnoiditis, as described by the surgeon, has been noted in 51 patients (13%). In 35 (68.6%), neuralgia was typical and in the other 17 (31.4%) it was atypical.
As expected by definition, neurovascular conflict was found in 49 interventions (96%); it was predominantly arterial in 27 (52.9%). Accompanying arachnoiditis was encountered: mild in 20 interventions (39.2%), severe in 31 (60.8%).
A successful result (BNI I or II) was achieved in 29 patients (56.9%). The other 22 patients (43.1%) had persistence or recurrence of pain. Overall KM probability of being pain free at 15 years was 72%.

Conclusions Intraoperative finding of arachnoiditis during MVD for classical trigeminal neuralgia is associated with poorer outcome than that of classical trigeminal neuralgia in general. This is particularly true for low grades of conflict.

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Microsurgical rhizotomy for trigeminal neuralgia in MS patients

J Neurosurg 130:1877–1888, 2019

Patients with multiple sclerosis (MS)–associated trigeminal neuralgia (TN) have higher recurrence and retreatment rates than non-MS patients. The optimal management strategy and role for microsurgical rhizotomy (MSR) for MS-TN remains to be determined. The aim of this study was to report time to treatment failure (TTF) and pain scores following MSR compared to percutaneous and Gamma Knife procedures.

METHODS Time to treatment failure was analyzed after MSR (n = 14) versus prior procedures (n = 53) among MS-TN patients. Kaplan-Meier curves and log-rank test were utilized to compare TTF after MSR versus prior procedures using the same cohort of patients as their own control group. Subsequent analysis compared TTF after MSR to TTF after 93 other procedures among a second cohort of 18 MS-TN patients not undergoing MSR. BNI pain scores were compared between MSR and other procedures among the MS-TN cohort using a chi-square test.

RESULTS TTF was significantly longer after MSR than after other procedures in the MSR cohort (median TTF 79 vs 10 months, respectively, p < 0.0001). Similarly, TTF was longer after MSR than after prior procedures in the non-MSR cohort (median TTF 79 vs 13 months, respectively, p < 0.001). MSR resulted in a higher proportion of excellent pain scores when compared to other procedures in the non-MSR cohort (77% vs 29%, p < 0.001). Probability of treatment survival was higher after MSR than after other procedures at all time points (3, 6, 12, 24, 36, and 48 months). There were no deaths or major complications after MSR.

CONCLUSIONS TTF was significantly longer following MSR compared to prior procedures in MS-TN patients. Additionally, a higher proportion of patients achieved excellent BNI pain scores after MSR.

 

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Hemodynamic features of offending vessels at neurovascular contact in patients with trigeminal neuralgia and hemifacial spasm

J Neurosurg 130:1870–1876, 2019

Offending vessels at the site of neurovascular contact (NVC) in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS) may have specific hemodynamic features. The purpose of this study was to investigate the wall shear stress (WSS) of offending vessels at NVCs by conducting a computational fluid dynamics (CFD) analysis.

METHODS The authors retrospectively analyzed the cases of 20 patients (10 with TN and 10 with HFS) evaluated by 3D CT angiography and used the imaging findings for analysis of the hemodynamic parameters. The 3D CFD images were directly compared with the NVCs determined by simulated multifusion images of CT angiogram and MR cisternogram, and operative photos. The magnitudes of the WSS (WSSm) at the proximal (WSSm-p), just-beginning (WSSm-j), contact site (WSSm-s), and distal (WSSm-d) areas of each NVC were analyzed. The ratios of the WSSm-j, WSSm-s, and WSSm-d areas to the WSSm-p area were calculated individually. The direction of the WSS (WSSv) and its temporal variation (WSSvV) were depicted and morphologically compared with the NVC confirmed by simulated images and operative findings.

RESULTS The ratios of WSSm at the just-beginning and the contact site to the proximal area of the NVCs (WSSm-j/ WSSm-p and WSSm-s/WSSm-p) were both significantly higher than that at the distal area (WSSm-d/WSSm-p) (p < 0.05). The WSSv and WSSvV at the NVCs showed small variation in a single cardiac cycle, especially along the areas that were in contact with the affected nerve.

CONCLUSIONS Areas of relatively high WSSm and temporal variation of WSSm (WSSmV) were observed at the NVCs. Less mobility of the WSSv and WSSvV was detected along the side of the vessels in contact with the nerves. These findings may be consistent with the actual area of the NVC. Hemodynamic features of the site of NVC can be added to the preoperative simulation for MVD surgery, which may be useful for the diagnosis and treatment planning of TN and HFS.

 

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Contemporary concepts of pain surgery

J Neurosurg 130:1039–1049, 2019

Pain surgery is one of the historic foundations of neurological surgery. The authors present a review of contemporary concepts in surgical pain management, with reference to past successes and failures, what has been learned as a subspecialty over the past 50 years, as well as a vision for current and future practice.

This subspecialty confronts problems of cancer pain, nociceptive pain, and neuropathic pain. For noncancer pain, ablative procedures such as dorsal root entry zone lesions and rhizolysis for trigeminal neuralgia (TN) should continue to be practiced. Other procedures, such as medial thalamotomy, have not been proven effective and require continued study. Dorsal rhizotomy, dorsal root ganglionectomy, and neurotomy should probably be abandoned.

For cancer pain, cordotomy is an important and underutilized method for pain control. Intrathecal opiate administration via an implantable system remains an important option for cancer pain management.

While there are encouraging results in small case series, cingulotomy, hypophysectomy, and mesencephalotomy deserve further detailed analysis.

Electrical neuromodulation is a rapidly changing discipline, and new methods such as high-frequency spinal cord stimulation (SCS), burst SCS, and dorsal root ganglion stimulation may or may not prove to be more effective than conventional SCS. Despite a history of failure, deep brain stimulation for pain may yet prove to be an effective therapy for specific pain conditions. Peripheral nerve stimulation for conditions such as occipital neuralgia and trigeminal neuropathic pain remains an option, although the quality of outcomes data is a challenge to these applications. Based on the evidence, motor cortex stimulation should be abandoned. TN is a mainstay of the surgical treatment of pain, particularly as new evidence and insights into TN emerge.

Pain surgery will continue to build on this heritage, and restorative procedures will likely find a role in the armamentarium. The challenge for the future will be to acquire higher-level evidence to support the practice of surgical pain management.

 

 

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Tentorial sling for microvascular decompression in patients with trigeminal neuralgia

J Neurosurg 130:1315–1320, 2019

Trigeminal neuralgia is a debilitating pain disorder most often caused by arterial compression of the trigeminal nerve, although there are other etiologies. Microvascular decompression (MVD) remains the most definitive treatment for this disorder, with cure rates reported between 60% and 80%. Traditional MVD techniques involve a retrosigmoid craniotomy with placement of an inert foreign material, such as Teflon, between the nerve and compressive vessel. Recurrence of trigeminal neuralgia after MVD has been associated with vessel migration, adhesion formation, and arterial pulsation against the Teflon abutting the nerve. Additionally, foreign materials such as Teflon have been reported to trigger inflammatory responses, resulting in recurrence of trigeminal pain. An alternative method for decompression involves the use of a sling to transpose the compressive vessel away from the nerve. Results of various sling techniques as a decompressive strategy are limited to small series and case reports. In this study, the authors present their experience utilizing a tentorial sling for MVD in patients with trigeminal neuralgia.

METHODS Institutional review board approval was obtained in order to contact patients who underwent MVD for trigeminal neuralgia via the tentorial sling technique. Clinical outcomes were assessed utilizing the Barrow Neurological Institute (BNI) pain intensity score immediately after surgery and at the time of the study.

RESULTS The tentorial sling technique was performed in 45 patients undergoing MVD for trigeminal neuralgia. In 41 of these patients, this procedure was their first decompressive surgery. Immediate postoperative relief of pain (BNI score I) was achieved in 80% of patients undergoing their first decompressive procedure. At last follow-up, 73% of these patients remained pain free. Three patients experienced recurrent trigeminal pain, with surgical exploration demonstrating an intact tentorial sling. The complication rate was 6.6%.

CONCLUSIONS Transposition techniques for MVD have been described previously in small series and case reports. This study represents the largest experience in which the utilization of a tentorial sling for MVD in patients with trigeminal neuralgia is described. The technique represents a novel method for decompression of the trigeminal nerve by transposition of the offending vessel without the use of foreign material. Although the authors’ preliminary results parallel the historical cure rate, further outcome data are required to assess long-term durability of this method.

 

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Trigeminal Nerve Atrophy Predicts Pain Recurrence After Gamma Knife Stereotactic Radiosurgery for Classical Trigeminal Neuralgia

Neurosurgery 84:927–934, 2019

Trigeminal nerve atrophy and neurovascular compression (NVC) are frequently observed in classical trigeminal neuralgia (CTN).

OBJECTIVE: To determine whether nerve characteristics contribute to Gamma Knife (ElektaAB, Stockholm, Sweden) surgery (GKS) outcomes in unilateral CTN without previous surgery.

METHODS: From 2006 to 2012, 67 patients with unilateral CTN without previous surgery received GKS with a maximal dose of 90 Gy delivered to the trigeminal nerve juxta brainstem. Two evaluators, blinded to the side of pain, analyzed the magnetic resonance images before GKS to obtain the parameters, including nerve cross-sectional area (CSA), vessel type of NVC, and site of NVC along the nerve. Correlations of the parameters with pain relief (Barrow Neurological Institute [BNI] grades I-IIIb) and recurrence (BNI grades VIV) were made by using Cox regression and Kaplan–Meier analyses.

RESULTS: The median CSA of the symptomatic nerves was significantly smaller than that of the asymptomatic nerves (4.95 vs 5.9 mm2, P < .001). After adjustment for age and sex, larger nerve CSA was associated with lower initial pain relief (hazard ratio 0.81, P=.03) and lower pain recurrence after initial response (hazard ratio 0.58, P= .02). Patients with nerve atrophy (CSA of ≤ 4.4 mm2 after receiver operating characteristic curve analysis) had a lower 5-yr probability of maintaining pain relief after initial response than those without nerve atrophy (65% vs 86%, P= .04).

CONCLUSION: Trigeminal nerve atrophy may predict pain recurrence in patients with initial post-GKS relief of CTN.Arterial and proximalNVCare not predictive ofGKS outcomes. Future studies are required to determine optimal treatments for long-term pain relief in patients with CTN and trigeminal nerve atrophy.

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Stereotactic radiosurgery for trigeminal neuralgia: a systematic review

J Neurosurg 130:733–757, 2019

The aims of this systematic review are to provide an objective summary of the published literature specific to the treatment of classical trigeminal neuralgia with stereotactic radiosurgery (RS) and to develop consensus guideline recommendations for the use of RS, as endorsed by the International Society of Stereotactic Radiosurgery (ISRS).

METHODS

The authors performed a systematic review of the English-language literature from 1951 up to December 2015 using the Embase, PubMed, and MEDLINE databases. The following MeSH terms were used in a title and abstract screening: “radiosurgery” AND “trigeminal.” Of the 585 initial results obtained, the authors performed a full text screening of 185 studies and ultimately found 65 eligible studies. Guideline recommendations were based on level of evidence and level of consensus, the latter predefined as at least 85% agreement among the ISRS guideline committee members.

RESULTS

The results for 65 studies (6461 patients) are reported: 45 Gamma Knife RS (GKS) studies (5687 patients [88%]), 11 linear accelerator (LINAC) RS studies (511 patients [8%]), and 9 CyberKnife RS (CKR) studies (263 patients [4%]). With the exception of one prospective study, all studies were retrospective.

The mean maximal doses were 71.1–90.1 Gy (prescribed at the 100% isodose line) for GKS, 83.3 Gy for LINAC, and 64.3–80.5 Gy for CKR (the latter two prescribed at the 80% or 90% isodose lines, respectively). The ranges of maximal doses were as follows: 60–97 Gy for GKS, 50–90 Gy for LINAC, and 66–90 Gy for CKR.

Actuarial initial freedom from pain (FFP) without medication ranged from 28.6% to 100% (mean 53.1%, median 52.1%) for GKS, from 17.3% to 76% (mean 49.3%, median 43.2%) for LINAC, and from 40% to 72% (mean 56.3%, median 58%) for CKR. Specific to hypesthesia, the crude rates (all Barrow Neurological Institute Pain Intensity Scale scores included) ranged from 0% to 68.8% (mean 21.7%, median 19%) for GKS, from 11.4% to 49.7% (mean 27.6%, median 28.5%) for LINAC, and from 11.8% to 51.2% (mean 29.1%, median 18.7%) for CKR. Other complications included dysesthesias, paresthesias, dry eye, deafferentation pain, and keratitis. Hypesthesia and paresthesia occurred as complications only when the anterior retrogasserian portion of the trigeminal nerve was targeted, whereas the other listed complications occurred when the root entry zone was targeted. Recurrence rates ranged from 0% to 52.2% (mean 24.6%, median 23%) for GKS, from 19% to 63% (mean 32.2%, median 29%) for LINAC, and from 15.8% to 33% (mean 25.8%, median 27.2%) for CKR. Two GKS series reported 30% and 45.3% of patients who were pain free without medication at 10 years.

CONCLUSIONS

The literature is limited in its level of evidence, with only one comparative randomized trial (1 vs 2 isocenters) reported to date. At present, one can conclude that RS is a safe and effective therapy for drug-resistant trigeminal neuralgia. A number of consensus statements have been made and endorsed by the ISRS.

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Older Patients Have Better Pain Outcomes Following Microvascular Decompression for Trigeminal Neuralgia

Neurosurgery 84:116–122, 2019

Trigeminal neuralgia (TN) increases in prevalence with age. Although microvascular decompression (MVD) is the most effective long-term operative treatment for TN, its use in older patient populations has been debated due to its invasive nature. Recent studies have demonstrated safety of MVD in older patients; however, efficacy data are more limited.

OBJECTIVE: To determine the relationship between age and pain outcomes following MVD for TN.

METHODS: Subjects underwent MVD for TN at our institution between 1/1/2004 and 12/31/2013, had typical TN, and demonstrated neurovascular compression on preoperative imaging.We performed a retrospective case series study by reviewing the electronic medical records and performing phone interviews to determine long-term outcomes. We divided patients into 2 groups for analysis, under 60 and 60 yr of age and older.

RESULTS: One hundred twenty-four subjects were included in the study, 82 under 60, and 42 60 yr of age and older. The average length of follow-up was 42.4 mo. Patients in the older age group had average pain score of 1.57 at most recent follow-up, while for the younger age group it was 2.18 (P = .0084). Multiple regression analysis found that older age, male gender, and preoperative medication responsiveness were significantly correlated with lower long-term pain scores, while V2 dermatome involvement was correlated with higher long-term pain scores.

CONCLUSION: Patients 60 yr of age and older have significantly better long-term pain outcomes following MVD than younger patients.

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Minimally Invasive Trigeminal Ablation: Novel Transoral Technique for Targeted Treatment of V3

World Neurosurg. (2018) 118:193-196

Trigeminal neuralgia (TN) is a chronic orofacial pain syndrome that presents with debilitating shooting pains in the V3 nerve distribution. The condition is traditionally responsive to anticonvulsant therapy; however, cases that become refractory to medications often require surgical intervention.

CASE DESCRIPTION: We present a case of TN that was treated with minimally invasive trigeminal ablation. The patient presented with a 6-year history of TN that had been resistant to medical management. The patient opted for minimally invasive management, refused stereotactic radiosurgery, and was treated using the minimally invasive trigeminal ablation approach. At 16 weeks postoperatively, the patient reported complete alleviation of pain with minimal sensorineural numbness.

CONCLUSIONS: The endoscopic approach allows for precise targeting through visual guidance, which is ideal in patients undergoing neuroablation for pain within specific nerve distributions. This is the first documented case of an endoscopic minimally invasive transoral approach toward ablative TN management.

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Veins of the Cerebellopontine Angle and Specific Complications of Sacrifice, with Special Emphasis on Microvascular Decompression Surgery

World Neurosurg. (2018) 117:422-432

Good knowledge of the anatomy of veins is of crucial importance for the functional surgery of cranial nerve (CN) disorders, especially microvascular decompression for trigeminal neuralgia (TN), hemifacial spasm (HFS), and vagoglossopharyngeal neuralgia (VGPN). Although controversial, veins may be involved in neurovascular conflicts and may constitute dangerous obstacles to access to the CNs. With the aim of estimating the implications of veins in those diseases and evaluating the linked surgical difficulties, we carried out a review of the literature from 2000 to the end of February 2018.

For this review, articles found on PubMed that gave enough precision about veins were retained (39 articles on TN, 38 on HFS, 8 on VGPN, and 26 on complications related to venous sacrifices). Before this review, we described a simplified anatomic classification of veins, amenable to easing the surgical approach to CNs.

Access to the trigeminal nerve, via the infratentorial-supracerebellar route, is almost always affected by the superficial superior petrosal venous system, whereas access to the facial and cochleovestibular complex as well as to the lower CNs, through the infrafloccular trajectory, is almost always exempt of important venous obstacles. Respective incidences of venous compression at the origin of hyperactive CN syndromes are given. The percentages of a venous conflict alone were calculated at 10.8% for TN, 0.1% for HFS, and 2.9% for VGPN.

We review the complications considered in relation with venous sacrifices. Precautions to minimize these complications are given.

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Suprafloccular approach via the petrosal fissure and venous corridors for microvascular decompression of the trigeminal nerve

J Neurosurg 129:324–333, 2018

Surgical exposure and decompression of the entire trigeminal nerve in a conventional lateral supracerebellar approach can be challenging because of blockages from the superior petrosal vein complex, cerebellum, and vestibulocochlear nerve. The authors demonstrate a novel suprafloccular approach via the petrosal fissure and venous corridors that can be used as a substitute for the conventional route used to treat trigeminal neuralgia and present a consecutive series of patients and their clinical outcomes.

METHODS Preoperative and postoperative clinical data from 420 patients who underwent this modified approach at Hangzhou First People’s Hospital between March 2012 and May 2014 were reviewed. The technique expands the working space by opening the petrosal fissure and dissecting adhesions between the vein of the cerebellopontine fissure and the simple lobule as needed. Via 3 surgical corridors, the entire trigeminal nerve is exposed and decompressed thoroughly with minimal retraction of the surrounding vital structures.

RESULTS The medial one-third of the trigeminal nerve accounted for the majority (275 [65.5%] cases) of neurovascular conflict sites. The lateral corridor was used in 219 (52.1%) cases, the medial corridor was used in 175 (41.7%) cases, and the intermediate corridor was used in 26 (6.2%) cases. The entire trigeminal nerve in each patient was accessed directly and decompressed properly. At the end of the 24-month follow-up period, the rate of excellent results (Kondo score of T0 or T1) was stable at approximately 90.5%. No complications were related directly to petrosal vein or vestibulocochlear nerve injury.

CONCLUSIONS Based on data from the large patient series, the authors found this suprafloccular approach via the petrosal fissure and venous corridors provides full exposure and decompression of the entire trigeminal nerve, a high cure rate, and a low neurovascular morbidity rate.

trigeminal neuralgia,suprafloccular,petrosal fissure, cerebellopontine fissure,venous corridor, clinical outcome, functional neurosurgery, pain

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Electromagnetic neuronavigation for the percutaneous treatment of trigeminal neuralgia with balloon compression

Acta Neurochirurgica (2018) 160:1337–1341

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

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

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

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

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The timing of stereotactic radiosurgery for medically refractory trigeminal neuralgia

Acta Neurochirurgica (2018) 160:977–986

Diffusion tensor imaging (DTI) is a novel MRI technique that enables noninvasive evaluation of microstructural alterations in white matter of brain. Initially, DTI was used in intra- or inter-hemispheric association bundles. Recent technical advances are overcoming the challenges of imaging small white matter bundles, such as the cranial nerves. In this study, we use DTI to shed more light on the microstructure changes in long-standing trigeminal neuralgia. We also utilize DTI to study the effect of early stereotactic radiosurgery (SRS) on the microstructures of the trigeminal nerve and to predict the effectiveness of early SRS in the treatment of medically refractory trigeminal neuralgia (TN).

Methods To analyze the presentation of trigeminal nerve, the DTI was reconstructed in 21 cases pre- and post-SRS. DTI parameters recorded include fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD), linear anisotropy coefficient (Cl), planar anisotropy coefficient (Cp), and spherical anisotropy coefficient (Cs). Comparisons between ipsilateral (symptomatic) and contralateral (asymptomatic) trigeminal nerves and symptomdurations of < 5 and ≧ 5 years were performed.

Results The study cohort comprised 21 patients with TN with a median age of 66 years. Initial adequate facial pain relief (Barrow Neurological Institute facial pain scores I–IIIb) was achieved in 16 (76%) patients. For the pre-SRS DTI findings, ipsilateral trigeminal nerve was associated with higher baseline root entry zone (REZ) Cs compared to contralateral nerve (0.774 vs. 0.743, p = 0.04). Ipsilateral trigeminal nerve with symptoms of < 5 years was associated with higher baseline FA compared to trigeminal nerve with symptoms of ≧ 5 years (0.314 vs. 0.244, p = 0.02). For the post-SRS DTI findings, ipsilateral trigeminal nerves with symptoms of <5 years demonstrated decrease in Cl, while those with symptoms ≧ 5 years demonstrated increase in Cl after SRS at the ipsilateral REZ (− 0.025 vs. 0.018, p = 0.04). At the cisternal segment of ipsilateral trigeminal nerve, symptoms of < 5 years were associated with decreased FA and increased λ2, while symptoms of ≧ 5 years were associated with increased FA and decreased λ2 after SRS (FA − 0.068 vs. 0.031, p = 0.04, λ2 0.0003 vs. − 0.0002, p = 0.02).

Conclusions SRS provides high rates of initial pain relief with moderate rates of facial hypoesthesia. Ipsilateral trigeminal nerve was associated with higher baseline REZ Cs, and baseline FAwas associated with duration of symptoms. There were significant associations between duration of symptoms and changes in ipsilateral REZ Cl, cisternal segment FA, and cisternal segment λ2 after SRS. These preliminary findings serve as comparisons for future studies investigating the use of DTI in radiosurgical planning for patients with TN.

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