A prospective cohort study of microvascular decompression and Gamma Knife surgery in patients with trigeminal neuralgia

When the nerve keeps firing: an institutional experience and systematic review on delayed response after microvascular decompression for trigeminal neuralgia

BACKGROUND

This study aimed to investigate the occurrence of delayed response following microvascular decompression (MVD) in patients with trigeminal neuralgia (TN) and identify potential contributing factors. Additionally, we present two cases with delayed relief observed at our institution.

METHOD

Two TN patients with delayed response and clear intra-operative arterial findings are presented in this study. Furthermore, we conducted a systematic review by searching electronic bibliographic databases, including MEDLINE (PubMed), Web of Science, Scopus, and Embase, from inception to 2022.

RESULTS

We identified a total of 28 full-text articles involving 322 TN patients who experienced delayed pain relief. Out of these, only 11 studies provided sufficient evidence and were included in the final analysis. Among the patients, 73.46% were female. The mean incidence rate of delayed response after MVD treatment for TN was 10.5%, with a range of 0.95 to 57.14% across different studies. The mean age of these patients was 59.86 years. The reported time to pain relief in the existing reports was at least 4 days post-surgery. In 72.88% of the reported cases, right-side dominance was observed. The majority of delayed cases experienced pain relief within 3 months, with a median time of 1 month.

CONCLUSIONS

A thorough examination of the probability of delayed pain relief after MVD for TN and understanding the characteristics of this phenomenon can offer surgeons valuable post-operative guidance and aid in decision-making regarding potential immediate reoperation.

Contact-free transposition and interposition techniques for trigeminal neuralgia: a systematic review

INTRODUCTION

Surgical treatment for trigeminal neuralgia (TGN), by means of interposition of material between nerve and offending vessel, has been shown to be highly efficient. In recent years, treatment by means of vessel transposition has become more frequent, as in singular cases of recurrence, nerval reactions towards interposed material have been noted. In this review we research the classic microvascular decompression (MVD) techniques (interposition) as well as the more recent transposition and their effectiveness, considering patient outcomes as well as complications and recurrences.

EVIDENCE ACQUISITION

We searched online databases MEDLINE and LIVIVO, using key words trigeminal neuralgia AND transposition/ AND sling/ AND non compressive technique/ AND microvascular decompression.

EVIDENCE SYNTHESIS

We included 8 studies for transposition and 20 studies for the interposition, combining for 2045 patients (302 for transposition and 1743 for interposition). 96.1% of patients in the transposition and 93.1% in the interposition group reported a positive outcome immediately postoperatively. At follow-up, 87.4% in the transposition group (follow-up 51.2 months) and 87.9% of patients in the interposition group (follow-up 36.5 months), reported a positive outcome. 16.2% of patients in the transposition and 13.1% in the interposition group had postoperative complications. Recurrence was reported in 5.6% of patients treated with transposition and 2.3% of patients treated with interposition.

CONCLUSIONS

Transposition presents similar results concerning short- and long-term patient satisfaction for treatment of TGN as well as similar numbers of complications of recurrences as interposition. Yet, current evidence is restricted to a few retrospective studies, thus, evidence is limited so far.

Effects of microvascular decompression on quality-of-life in trigeminal neuralgia patients aged 70 years and older

Background

Trigeminal neuralgia (TN) occasionally affects older adults, frequently worsens, and becomes refractory to medication. Older adult patients with TN may consider microvascular decompression (MVD) for their treatment. No study examines MVD effects on older adult TN patients' health-related quality of life (HRQoL). The present study evaluates the HRQoL of TN patients aged 70 years and older before and after MVD.

Methods

Adult TN patients who underwent MVD evaluated their HRQoL using the 36-Item Short-form (SF-36) Health Survey before and 6 months after MVD. The patients were divided into four groups according to their decade of age. The clinical parameters and operative outcomes were analyzed statistically. The SF-36 physical, mental, and role social component summary scores and eight domain scale scores were analyzed using a twoway repeated-measures analysis of variance (ANOVA) to compare the effects of age group and preoperative and postoperative time points.

Results

Among 57 adult patients (34 women, 23 men; mean age, 69 years; range, 30-89 years), 21 patients were in their seventies, and 11 were in their eighties. The SF-36 scores of patients in all age groups improved after MVD. Two-way repeated-measures ANOVA demonstrated a significant age group effect on the physical component summary and its physical functioning domain. A time point effect was significant on all component summaries and domains. There was a significant interaction between age group and time point effects on the bodily pain domain. These results suggested that patients 70 years and older had significant postoperative HRQoL improvement, but their improvement of physical-related HRQoL and multiple physical pain issues were limited.

Conclusion

Impaired HRQoL in TN patients aged 70 years and older can improve after MVD. Careful management of multiple comorbidities and surgical risks enables MVD to be an appropriate treatment for older adult patients with refractory TN.

Glossopharyngeal Neuralgia

Glossopharyngeal neuralgia (GPN) is a rare disease that must be differentiated from trigeminal neuralgia. The purpose of this article is to provide a comprehensive review of anatomy, pathophysiology, diagnostic criteria, and several options of treatment for GPN. Lessons learned through our experience of treating GPN are presented in detail, as well as cases of misdiagnosis and diagnostic pitfalls. Microvascular decompression (MVD) should be primarily considered for medically intractable GPN. Techniques employed in MVD for GPN are categorized and described. Especially, we underscore the advantages of the 'transposition' technique where insulating material is positioned 'off' the root entry zone (REZ), instead of 'on' it. We believe this 'off-the-REZ' technique can fundamentally prevent recurrence, if applicable. In addition, Gamma Knife radiosurgery can be an alternative option when a patient is ineligible for MVD, though it is categorized as a destructive procedure.

Microvascular decompression in trigeminal neuralgia - a prospective study of 115 patients

Background

Trigeminal neuralgia is a severe facial pain disorder. Microvascular decompression is first choice surgical treatment of patients with classical TN. There exist few prospective studies with an independent evaluation of efficacy and complications after MVD.

Objectives

We aimed to assess outcome and complications after microvascular decompression from our center.

Methods

We prospectively recorded clinical characteristics, outcome, and complications from consecutive patients with either classical or idiopathic (only patients with a neurovascular contact) trigeminal neuralgia undergoing microvascular decompression. Neurovascular contact was evaluated by 3.0 Tesla MRI. Patients were assessed before and 3, 6, 12, and 24 months after surgery by independent assessors.

Results

Of 115 included patients, 86% had a clinically significant outcome (i.e., BNI I – BNI IIIb). There was a significant association between an excellent surgical outcome and the male sex (OR 4.9 (CI 1.9–12.8), p = 0.001) and neurovascular contact with morphological changes (OR 2.5 (CI 1.1–6.0), p = 0.036). Significantly more women (12/62 = 19%) than men (2/53 = 4%) had a failed outcome, p = 0.019. The most frequent major complications were permanent hearing impairment (10%), permanent severe hypoesthesia (7%), permanent ataxia (7%), and stroke (6%). Most patients (94%) recommend surgery to others.

Conclusion

Microvascular decompression is an effective treatment for classical and idiopathic (only patients with a neurovascular contact) trigeminal neuralgia with a high chance of a long-lasting effect. The chance of an excellent outcome was highest in men and in patients with classical trigeminal neuralgia. Complications are relatively frequent warranting thorough patient evaluation and information preoperatively.

Trial registration

Clinical.trials.gov registration no. NCT04445766.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01520-x.

Sagittal Angle of the Trigeminal Nerve at the Porus Trigeminus: A Novel Measurement to Distinguish Different Causes of Classic Trigeminal Neuralgia

BACKGROUND AND PURPOSE

Classic trigeminal neuralgia is a clinical syndrome of facial pain, most often attributable to vascular compression of the proximal cisternal segment of the trigeminal nerve and treatable with microvascular decompression of the nerve. Some patients, however, meet all clinical criteria for classic trigeminal neuralgia yet do not respond to microvascular decompression. Because the reasons for surgical failure are not well understood, the aim of this study was to determine if a subset of patients with classic trigeminal neuralgia could be distinguished by measuring the angle of the trigeminal nerve in the sagittal plane as the nerve traverses the porus trigeminus.

MATERIALS AND METHODS

We retrospectively identified patients with either classic trigeminal neuralgia (n = 300) or hemifacial spasm (n = 300) who had undergone MR imaging, including 3-plane steady-state free precession imaging. Patients with hemifacial spasm served as controls. On sagittal steady-state free precession images, we measured the angle of each trigeminal nerve as it crosses through the porus trigeminus into the Meckel cave (SATNaPT). In patients with classic trigeminal neuralgia, we separated the nerves into symptomatic and asymptomatic sides. We compared these 3 groups using the Student t test.

RESULTS

Control patients had a mean SATNaPT of 170° (SD, 11°) with a normal distribution. The contralateral asymptomatic nerve in patients with classic trigeminal neuralgia had the same distribution of angles. The symptomatic nerves in patients with classic trigeminal neuralgia had a bimodal distribution; 83% of patients fell into the same distribution as the asymptomatic nerves, but the other 15% had an average angle of 143° (SD, 7°). This difference was statistically significant (P < .0001).

CONCLUSIONS

Patients with the clinical syndrome of classic trigeminal neuralgia fell into 2 categories based on the radiologic measurement of the SATNaPT. Most patients had an anatomically normal nerve that was affected by vascular compression, but 17% of these patients had aberrant anatomy that may cause or contribute to their clinical presentation. Further study is needed to determine whether this subset of patients should receive a different surgery to better address their underlying anatomic abnormality. The SATNaPT measurement should be included in every MR imaging interpretation performed on patients with classic trigeminal neuralgia.

Incidence of repeat procedures and healthcare utilization following surgery, radiosurgery, and percutaneous procedures in elderly patients with trigeminal neuralgia

OBJECTIVE

Management of trigeminal neuralgia (TN) in elderly patients poses significant challenges. The impact of different treatment modalities (surgery, radiosurgery [RS], and percutaneous techniques [PTs]) on healthcare utilization is not well defined in the management of TN in elderly patients. The aim of this study was to compare the long-term healthcare utilization metrics of different interventions in the management of elderly patients with TN.

METHODS

The MarketScan database was queried using the International Classification of Diseases, Ninth Revision and Current Procedural Terminology, from 2000 to 2016. TN patients ≥ 65 years of age managed using surgery, RS, and PTs with at least 5 years of follow-up after the index procedure were included. Outcomes analyzed were hospital admissions, outpatient services, and medication refills.

RESULTS

Of 993 patients, 43% (n = 430) underwent RS, 44% (n = 432) had PTs, and only 13% (n = 131) underwent surgery for TN. Overall, the median age of patients was 74 years old, 64% were females, 90% had Medicare insurance, and 17% had an Elixhauser index ≥ 3. Patients in the surgery group were younger (median age 71 years) with a higher comorbidity index (≥ 3; 24%) compared with patients undergoing RS and PTs (13% and 17%, respectively). At 1, 2, and 5 years after the index procedure, 41%, 48%, and 57% of patients in the PT cohort underwent any repeat procedure compared with 11%, 18%, and 29% for the RS cohort, and 6%, 9%, and 11% for the surgical cohort, respectively. Also, patients in the PT cohort incurred 1.8, 1.9, and 2.0 times the combined payment at 1, 2, and 5 years, respectively, compared with the surgery cohort. Similarly, patients who underwent RS for TN incurred 1.4, 1.5, and 1.5 times the combined payment at 1, 2, and 5 years, respectively, compared with the surgery cohort. At 5 years after the index procedure, combined payments for the PT cohort were $79,753 (IQR $46,013, $144,064) compared with $61,016 (IQR $27,114, $117,097) for the RS cohort and $41,074 (IQR $25,392, $87,952) for the surgery cohort (p < 0.0001).

CONCLUSIONS

PTs followed by RS were the common procedures used in the majority of elderly patients with TN. However, surgery for TN resulted in durable control with the least need for reoperations up to 5 years after the index procedure, followed by RS and PTs. PTs for TN resulted in the highest utilization of healthcare resources and need for reoperations at all time points. These findings should be considered in clinical decision-making when selecting appropriate treatment modalities in elderly patients with TN.

Gamma Knife Radiosurgery for Trigeminal Neuralgia : Review and Update

Accurate diagnosis of trigeminal neuralgia (TN) is the starting point for optimal treatment. Gamma knife radiosurgery (GKRS) is currently regarded as one of the first-line treatment options for medically refractory TN. GKRS is a less invasive treatment with a low risk of complications than other surgical procedures that provides a favorable pain control (BNI I–IIIb) rate of >75% at short-term follow-up. Drawbacks of GKRS include the latency period before pain relief and higher recurrence rate compared with microvascular decompression. Therefore, repeat treatment is necessary if the initial GKRS was effective but followed by recurrence. The concept of dose rate and the biologically effective dose of radiation has been actively studied in radiation oncology and is also applied in GKRS for TN to achieve high safety and efficacy by prescribing the optimal dose. Recent progress in functional imaging, such as diffusion tensor imaging, enables us to understand the pathophysiology of TN and predict the clinical outcome after GKRS. Here, we review TN, GKRS, and recent updates, especially in the concepts of radiation dose, diffusion tensor imaging studies, and repeat treatment in GKRS for TN.

Trigeminal neuralgia and other cranial pain syndromes

Spontaneous Trigeminal Neuralgia is a painful condition of the face which may require interventional treatment if medicines fail to control the pain. These include microvascular decompression (MVD) and GKNS. The former is moderately more effective but GKNS has become accepted both as an alternative to MVD or as an adjunct. Like all treatments of the condition, it is successful in a majority of patients but by no means all. Repeat treatments are possible. When Trigeminal Neuralgia is secondary to other conditions the response to GKNS is different. With AVMs, Dural Arteriovenous Fistulae and Epidermoids, the dose to treat the visible lesion usually cures the neuralgia. With meningiomas it is necessary to treat the neuralgia as a separate entity with a neuralgia dose focused on the nerve. GKNS does not improve the rare neuralgia associated with Vestibular Schwannomas. It works with Multiple Sclerosis but not as well as with the spontaneous illness. There is some evidence that GKNS can be useful with the rare Glossopharyngeal and Sphenopalatine Neuralgias.

Double collagen matrix grafting for dural closure in microvascular decompression: an alternative use of autologous fascial grafting

BACKGROUND

Watertight dural closure is a crucial step in preventing postoperative cerebrospinal fluid (CSF) leak and subsequent infection in posterior fossa surgery. The aim of this study is to assess an alternative use of collagen matrix double grafting in microvascular decompression (MVD).

METHODS

Dural closure using double collagen matrix grafts was retrospectively compared with autologous fascial grafting in 120 patients who underwent MVD. Double collagen matrix grafting technique, a combination use of inlay and onlay grafting (DuraGen^®, Integra Lifesciences, Plainsboro, NJ, USA, $700-800 for an MVD craniotomy size), was applied in 60 patients (the collagen matrix group). In the remaining 60 patients, an autologous fascial graft was sutured in a watertight fashion to the dural defect (the fascia group). Postoperative wound complications, such as CSF leak and infection, were retrospectively compared between the two groups.

RESULTS

CSF leaks were observed in 3 patients (5.0%) in the fascia group and in 2 patients (3.3%) in the collagen matrix group. All cases of CSF leakage presented with pseudomeningoceles except one patient who developed an incisional CSF leak. A repair surgery for CSF leak was required in this one patient in the fascia group. Subcutaneous abscesses were noted in 2 patients (3.3%) in the fascia group. There was no patient who developed a subcutaneous abscess in the collagen matrix group. One patient in each group developed aseptic meningitis. Statistical analyses revealed that the collagen matrix group showed non-inferior outcomes to the fascia group in CSF leaks and infectious complications.

CONCLUSIONS

Double grafting technique with a combination of inlay and onlay collagen sheets is a safe and secure alternative for watertight dural closure despite a cost limitation.

Microvascular decompression as a second step treatment for trigeminal neuralgia in patients with failed two-isocentre gamma knife radiosurgery

OBJECTIVE

Subsequent microvascular decompression (MVD) might be affected by the previous two-isocentre gamma knife radiosurgery (GKS) due to the tissue changes caused by its higher dose radiation and larger treatment volume. This study aimed to evaluate the safety and efficacy of MVD as a second step treatment after two-isocentre GKS.

METHODS

Between December 2016 and May 2019, data from 19 consecutive trigeminal neuralgia (TN) patients who experienced MVD after failed two-isocentre GKS were collected. The clinical characteristics, intraoperative findings, surgical outcomes and complications were reviewed and compared with 158 patients who underwent MVD as an initial treatment.

RESULTS

Fifteen patients (78.9%) achieved complete pain relief (Barrow Neurological Institute, BNI class I) immediately after surgery and nine patients (47.4%) maintained complete pain relief at the last follow-up, which was similar to patients who underwent initial MVD. The median follow-up period was 36 months. The incidence of new or worsened facial numbness showed no statistical significance between the groups. During surgery, trigeminal nerve atrophy was noted in 9 patients (47.4%), thickened arachnoid in 3 patients (15.8%), atherosclerotic plaque in 3 patients (15.8%) and neurovascular adhesion in 1 patient (5.3%).

CONCLUSIONS

MVD remains an effective and safe rescue therapy for patients who elect the minimally invasive treatment with two-isocentre GKS for the first time, without an increased risk of facial numbness.

Microvascular Transposition Without Teflon: A Single Institution's 17-Year Experience Treating Trigeminal Neuralgia

BACKGROUND

Trigeminal neuralgia (TN) refractory to medical management is often treated with microvascular decompression (MVD) involving the intracranial placement of Teflon. The placement of Teflon is an effective treatment, but does apply distributed pressure to the nerve and has been associated with pain recurrence.

OBJECTIVE

To report the rate of postoperative pain recurrence in TN patients who underwent MVD surgery using a transposition technique with fibrin glue without Teflon.

METHODS

Patients were eligible for our study if they were diagnosed with TN, did not have multiple sclerosis, and had an offending vessel that was identified and transposed with fibrin glue at our institution. All eligible patients were given a follow-up survey. We used a Kaplan-Meier (KM) model to estimate overall pain recurrence.

RESULTS

A total of 102 patients met inclusion criteria, of which 85 (83%) responded to our survey. Overall, 76 (89.4%) participants responded as having no pain recurrence. Approximately 1-yr pain-free KM estimates were 94.1% (n = 83), 5-yr pain-free KM estimates were 94.1% (n = 53), and 10-yr pain-free KM estimates were 83.0% (n = 23).

CONCLUSION

Treatment for TN with an MVD transposition technique using fibrin glue may avoid some cases of pain recurrence. The percentage of patients in our cohort who remained pain free at a maximum of 17 yr follow-up is on the high end of pain-free rates reported by MVD studies using Teflon. These results indicate that a transposition technique that emphasizes removing any compression near the trigeminal nerve root provides long-term pain-free rates for patients with TN.

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.

Microvascular decompression: incidence and prevention of postoperative CSF leakage in a consecutive series of 134 patients

Introduction: Microvascular decompression (MVD) is an established procedure for treating Trigeminal Neuralgia and Hemifacial Spasm. Postoperative CSF leakage is still a common complication after MVD.Material and Methods: We did a retrospective study of 134 patients who underwent microvascular decompression, mainly for Trigeminal Neuralgia and Hemifacial Spasm in our unit. All patients had an apparently watertight repair of the dura at the end of the operation done by our technique using Duraguard ® and Histacryl® glue.Results: Of the 134 patients, 129 (96.2%) had no postoperative CSF leakage. Only five (3.7%) of the patients experienced postoperative CSF leak.Conclusion: We conclude that dural repair using the described technique, with a dural substitute (Duraguard) and Histacryl glue is safe and effective in preventing postoperative CSF leakage following MVD.

Electroacupuncture therapy for change of pain in classical trigeminal neuralgia

INTRODUCTION

Classical trigeminal neuralgia (CTN) is a kind of trigeminal neuralgia which is due to neurovascular compression. The common neurological treatment CTN drug called carbamazepine is the main measure, although it usually has side effects and a high-rate of relapse. As a critical alternative therapy, electroacupuncture (EA) has been shown to benefit for neuropathic pain. The aims of this study are to observe the therapeutic effect and safety of EA for CTN, to evaluate whether EA has the advantage over carbamazepine in the analgesia of CTN. Furthermore, we would to establish a standardized, effective, and convenient therapy program of EA.

METHODS AND ANALYSIS

One hundred twenty patients diagnosed with CTN will be randomized for a 4-week intervention. The interventions will be different according to the four groups (EA + carbamazepine group, sham EA + carbamazepine group, EA + placebo group and sham EA + placebo group). EA therapy will be performed in specific acupoints with a dilute wave (2/100 Hz) for 60 minutes. Carbamazepine tablets will be taken orally with 0.1 g each time, thrice daily. Sham EA and placebo intervention will not receive EA and drug treatment. The main outcomes are the change from baseline intensity of pain at 6 months (pain evaluation by visual analogue score) and the change from baseline brief introduction of 2-week pain to evaluate pain comprehensively. The data management and statistical analysis will be conducted by third party statisticians. Incidence of adverse events will be investigated.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Clinical Trial Ethics Committee of The Third Affiliated Hospital of Zhejiang Chinese Medical University (NO. ZSLL-KY-2017-033) and Jiaxing Hospital of Traditional Chinese Medicine (NO. 2018-JZLK-002). The results will be disseminated by presentation at peer-reviewed journals.

Patterns of opioid use in patients with trigeminal neuralgia undergoing neurosurgery

OBJECTIVE

First-line treatment for trigeminal neuralgia (TN) is pharmacological management using antiepileptic drugs (AEDs), e.g., carbamazepine (CBZ) and oxcarbazepine (OCBZ). Surgical intervention has been shown to be an effective and durable treatment for TN that is refractory to medical therapy. Despite the lack of evidence for efficacy in patients with TN, the authors hypothesized that patients with neuropathic facial pain are prescribed opioids at high rates, and that neurosurgical intervention may lead to a reduction in opioid use.

METHODS

This is a retrospective study of patients with facial pain seen by a single neurosurgeon. All patients completed a survey on pain medications, medical comorbidities, prior interventions for facial pain, and a validated pain outcome tool (the Penn Facial Pain Scale). Patients subsequently undergoing neurosurgical intervention completed a survey at the 1-month follow-up in the office, in addition to telephone interviews using a standardized script between 1 and 6 years after intervention. Univariate and multivariate logistic regression were used to predict opioid use.

RESULTS

The study cohort consisted of 309 patients (70% Burchiel type 1 TN [TN1], 18% Burchiel type 2 [TN2], 6% atypical facial pain [AFP], and 6% TN secondary to multiple sclerosis [TN-MS]). At initial presentation, 20% of patients were taking opioids. Of these patients, 55% were receiving concurrent opioid therapy with CBZ/OCBZ, and 84% were receiving concurrent therapy with at least one type of AED. Facial pain diagnosis (for diagnoses other than TN1, odds ratio [OR] 2.5, p = 0.01) and facial pain intensity at its worst (for each unit increase, OR 1.4, p = 0.005) were predictors of opioid use at baseline. Neurosurgical intervention led to a reduction in opioid use to 8% at long-term follow-up (p < 0.01, Fisher's exact test; n = 154). Diagnosis (for diagnoses other than TN1, OR 4.7, p = 0.002) and postintervention reduction in pain at its worst (for each unit reduction, OR 0.8, p < 10-3) were predictors of opioid use at long-term follow-up. On subgroup analysis, patients with TN1 demonstrated a decrease in opioid use to 5% at long-term follow-up (p < 0.05, Fisher's exact test), whereas patients with non-TN1 facial pain did not. In the nonsurgical group, there was no statistically significant decrease in opioid use at long-term follow-up (n = 81).

CONCLUSIONS

In spite of its high potential for abuse, opioid use, mostly as an adjunct to AEDs, is prevalent in patients with facial pain. Opportunities to curb opioid use in TN1 include earlier neurosurgical intervention.

Long-term pain outcomes for recurrent idiopathic trigeminal neuralgia after stereotactic radiosurgery: a prospective comparison of first-time microvascular decompression and repeat stereotactic radiosurgery

OBJECTIVE

Microvascular decompression (MVD) and stereotactic radiosurgery (SRS) are common surgical treatments for trigeminal neuralgia (TN). Many patients who receive SRS have pain recurrence; the ideal second intervention is unknown. The authors directly compared pain outcomes after MVD and repeat SRS in a population of patients in whom SRS failed as their first-line procedure for TN, and they identified predictors of pain control.

METHODS

The authors reviewed a prospectively collected database of patients undergoing surgery for TN between 1997 and 2014 at the University of California, San Francisco (UCSF). Standardized data collection focused on preoperative clinical characteristics, surgical characteristics, and postoperative outcomes. Patients with typical type 1, idiopathic TN with ≥ 1 year of follow-up were included.

RESULTS

In total, 168 patients underwent SRS as their first procedure. Of these patients, 90 had residual or recurrent pain. Thirty of these patients underwent a second procedure at UCSF and had ≥ 1 year of follow-up; 15 underwent first-time MVD and 15 underwent repeat SRS. Patients undergoing MVD were younger than those receiving repeat SRS and were more likely to receive ≥ 80 Gy during the initial SRS. The average follow-up was 44.9 ± 33.6 months for MVD and 48.3 ± 45.3 months for SRS. All patients achieved complete pain freedom without medication at some point during their follow-up. At last follow-up, 80% of MVD-treated patients and 33.3% of SRS-treated patients had a favorable outcome, defined as Barrow Neurological Institute Pain Intensity scores of I-IIIa (p < 0.05). Percentages of patients with favorable outcome at 1 and 5 years were 86% and 75% for the MVD cohort and 73% and 27% for the SRS cohort, respectively (p < 0.05). Multivariate Cox proportional hazards analysis demonstrated that performing MVD was statistically significantly associated with favorable outcome (HR 0.12, 95% CI 0.02-0.60, p < 0.01). There were no statistically significant predictors of favorable outcome in the MVD cohort; however, the presence of sensory changes after repeat SRS was associated with pain relief (p < 0.01).

CONCLUSIONS

Patients who received MVD after failed SRS had a longer duration of favorable outcome compared to those who received repeat SRS; however, both modalities are safe and effective. The presence of post-SRS sensory changes was predictive of a favorable pain outcome in the SRS cohort.

[Stereotactic radiosurgery in treatment of trigeminal neuralgia]

It was not until relatively recently that the method of stereotactic radiosurgery has started to be used for treating trigeminal neuralgia. Being minimally invasive, this method can be considered an attractive alternative to invasive surgical methods.

OBJECTIVE

The objective of this study was to analyze the results of treatment in patients with trigeminal neuralgia using the Leksell Gamma Knife system.

MATERIAL AND METHODS

The results of stereotactic radiosurgery were analyzed in 52 patients (31 females and 21 males aged 31 to 79 years) who had undergone treatment at the Radiosurgical Center of MIBS (St. Petersburg) in 2009-2016. Forty-four patients were diagnosed with typical trigeminal neuralgia; four patients, with atypical neuralgia; and four patients, with symptomatic neuralgia (accompanying multiple sclerosis). Pain severity was assessed using the Visual Analogue Scale (VAS) and the Barrow Neurological Institute Scale (BNIPS) before and after the surgery, as well as during the follow-up period (mean duration, 3 years).

RESULTS

Pain was reduced in 38 (86.4%) patients with type 1 neuralgia. The effect usually was not observed immediately after the surgery but was delayed from several weeks to 12 months (median, 2 months; interquartile range) [1, 4]. The surgery was ineffective in 6 (14%) patients. Eight (18%) patients had a relapse on average after 2 years and 5 months. By the end of the follow-up period, score I according to the BNIPS was achieved in 22 (50%) patients; score II or III was achieved in 7 (16%) patients. Primary reduction of pain was achieved in two patients with type 2 neuralgia; one of them had a relapse after 19 months. Among patients with symptomatic neuralgia, the primary effect was achieved in three patients, but two of them later had a relapse.

CONCLUSION

Stereotactic radiosurgery can be used to alleviate pain in most patients with type 1 trigeminal neuralgia, but its results are inferior to those of invasive interventions. According to our findings, 18% of patients had a relapse. For patients with multiple sclerosis accompanied by type 2 and symptomatic trigeminal neuralgia, this method is not sufficiently effective. When both microvascular decompression and stereotactic radiosurgery can be used to treat for type 1 and 2 trigeminal neuralgia, patient's choice is crucial. It is important to inform the patient both about the potential complications of the interventions and about the delayed effect of the surgery and relapse frequency.

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

OBJECTIVE

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.

Stereotactic radiosurgery for trigeminal neuralgia: a systematic review

OBJECTIVES

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.

Efficacy of Neurectomy of Peripheral Branches of the Trigeminal Nerve in Trigeminal Neuralgia: A Critical Review of the Literature

Introduction

Of the many chronic painful conditions, trigeminal neuralgia (TN) affecting the orofacial region needs the particular attention of physicians and surgeons, especially those specialising in the maxillofacial region. Treatment protocols for the management of classic TN include pharmacology and surgical intervention. Oral and maxillofacial surgeons have traditionally employed the peripheral neurectomy in the surgical management of TN. This review aims to evaluate the efficacy of peripheral neurectomy in the management of TN with regard to (a) the relief of symptoms in comparison with standard neurosurgical procedures and (b) the duration of pain relief and complications observed compared to standard neurosurgical procedures.

Methods

The review of the literature was done according to PRISMA guidelines and included randomised controlled trials, reviews and prospective clinical studies involving surgical procedures for the management of TN. The primary outcomes evaluated were (a) initial relief of pain, (b) duration of relief of pain, (c) complications observed with ablative procedures and (d) recurrence of symptoms. A total of 43 studies fulfilled the inclusion criteria.

Results

In a total of 7913 patients from the 43 studies, central procedures were found to have best results for both quality and duration of pain relief. Percutaneous and peripheral procedures were associated with increased recurrence rates. The consolidated rates of complication for peripheral, percutaneous and central procedures were 39.46, 65.42 and 10.41%, respectively. The use of peripheral neurectomy alone in the management of classic TN was observed in 10 studies.

Conclusion

Peripheral neurectomy in TN is associated with lesser quality of pain relief in comparison with central neurosurgical procedures. It also provides only short- to medium-term pain relief. Most studies with the use of peripheral neurectomy involved only a small group of patients with short follow-up periods. Oral and maxillofacial surgeons must not consider the peripheral neurectomy as the first surgical option in the management of classic TN. Long-term results can be achieved better with appropriate central neurosurgical procedures and pharmacotherapy.

Comparative efficacy and acceptability of antiepileptic drugs for classical trigeminal neuralgia: a Bayesian network meta-analysis protocol

INTRODUCTION

Trigeminal neuralgia (TN) affects 4 to 28.9/100 000 people worldwide, and antiepileptic drugs such as carbamazepine and oxcarbazepine are the firstline treatment options. However, the efficacy and safety of other antiepileptic drugs remain unclear due to insufficient direct comparisons.

OBJECTIVE

To compare the efficacy and acceptability of all currently available antiepileptic agents for the treatment of patients with classical TN.

METHODS

We will search the PubMed, EMBASE, Cochrane Library and Web of Science databases for unpublished or undergoing research listed in registry platforms. We will include all randomised controlled trials comparing two different antiepileptic drugs or one antiepileptic drug with placebo in patients with classical TN. The primary outcomes will be the proportion of responders and the number of subjects who dropout during the treatment. The secondary outcomes will include the two primary outcomes but in the follow-up period, changes in the self-reporting assessment scale for neuralgia and quality of life assessment. In terms of network meta-analysis, we will fit our model to a Bayesian framework using the JAGS and pcnetmeta packages of the R project.

ETHICS AND DISSEMINATION

This protocol will not disseminate any private patient data. The results of this review will be disseminated through peer reviewed publication.

PROSPERO REGISTRATION NUMBER

CRD42016048640.

Hearing Loss following Posterior Fossa Microvascular Decompression: A Systematic Review

Objectives (1) Determine the prevalence of hearing loss following microvascular decompression (MVD) for trigeminal neuralgia (TN) and hemifacial spasm (HFS). (2) Demonstrate factors that affect postoperative hearing outcomes after MVD. Data Sources PubMed-NCBI, Scopus, CINAHL, and PsycINFO databases from 1981 to 2016. Review Methods Systematic review of prospective cohort studies and retrospective reviews in which any type of hearing loss was recorded after MVD for TN or HFS. Three researchers extracted data regarding operative indications, procedures performed, and diagnostic tests employed. Discrepancies were resolved by mutual consensus. Results Sixty-nine references with 18,233 operations met inclusion criteria. There were 7093 patients treated for TN and 11,140 for HFS. The overall reported prevalence of hearing loss after MVD for TN and HFS was 5.58% and 8.25%, respectively. However, many of these studies relied on subjective measures of reporting hearing loss. In 23 studies with consistent perioperative audiograms, prevalence of hearing loss was 13.47% for TN and 13.39% for HFS, with no significant difference between indications ( P = .95). Studies using intraoperative brainstem auditory evoked potential monitoring were more likely to report hearing loss for TN (relative risk [RR], 2.28; P < .001) but not with HFS (RR, 0.88; P = .056). Conclusion Conductive and sensorineural hearing loss are important complications following posterior fossa MVD. Many studies have reported on hearing loss using either subjective measures and/or inconsistent audiometric testing. Routine perioperative audiogram protocols improve the detection of hearing loss and may more accurately represent the true risk of hearing loss after MVD for TN and HFS.

Prospective comparison of long-term pain relief rates after first-time microvascular decompression and stereotactic radiosurgery for trigeminal neuralgia

OBJECTIVE

Common surgical treatments for trigeminal neuralgia (TN) include microvascular decompression (MVD), stereotactic radiosurgery (SRS), and radiofrequency ablation (RFA). Although the efficacy of each procedure has been described, few studies have directly compared these treatment modalities on pain control for TN. Using a large prospective longitudinal database, the authors aimed to 1) directly compare long-term pain control rates for first-time surgical treatments for idiopathic TN, and 2) identify predictors of pain control.

METHODS

The authors reviewed a prospectively collected database for all patients who underwent treatment for TN between 1997 and 2014 at the University of California, San Francisco. Standardized collection of data on preoperative clinical characteristics, surgical procedure, and postoperative outcomes was performed. Data analyses were limited to those patients who received a first-time procedure for treatment of idiopathic TN with > 1 year of follow-up.

RESULTS

Of 764 surgical procedures performed at the University of California, San Francisco, for TN (364 SRS, 316 MVD, and 84 RFA), 340 patients underwent first-time treatment for idiopathic TN (164 MVD, 168 SRS, and 8 RFA) and had > 1 year of follow-up. The analysis was restricted to patients who underwent MVD or SRS. Patients who received MVD were younger than those who underwent SRS (median age 63 vs 72 years, respectively; p < 0.001). The mean follow-up was 59 ± 35 months for MVD and 59 ± 45 months for SRS. Approximately 38% of patients who underwent MVD or SRS had > 5 years of follow-up (60 of 164 and 64 of 168 patients, respectively). Immediate or short-term (< 3 months) postoperative pain-free rates (Barrow Neurological Institute Pain Intensity score of I) were 96% for MVD and 75% for SRS. Percentages of patients with Barrow Neurological Institute Pain Intensity score of I at 1, 5, and 10 years after MVD were 83%, 61%, and 44%, and the corresponding percentages after SRS were 71%, 47%, and 27%, respectively. The median time to pain recurrence was 94 months (25th–75th quartiles: 57–131 months) for MVD and 53 months (25th–75th quartiles: 37–69 months) for SRS (p = 0.006). A subset of patients who had MVD also underwent partial sensory rhizotomy, usually in the setting of insignificant vascular compression. Compared with MVD alone, those who underwent MVD plus partial sensory rhizotomy had shorter pain-free intervals (median 45 months vs no median reached; p = 0.022). Multivariable regression demonstrated that shorter preoperative symptom duration (HR 1.005, 95% CI 1.001–1.008; p = 0.006) was associated with favorable outcome for MVD and that post-SRS sensory changes (HR 0.392, 95% CI 0.213–0.723; p = 0.003) were associated with favorable outcome for SRS.

CONCLUSIONS

In this longitudinal study, patients who received MVD had longer pain-free intervals compared with those who underwent SRS. For patients who received SRS, postoperative sensory change was predictive of favorable outcome. However, surgical decision making depends upon many factors. This information can help physicians counsel patients with idiopathic TN on treatment selection.

Diabetes and morbid obesity are associated with higher reoperation rates following microvascular decompression surgery: An ACS-NSQIP analysis

Background:

Microvascular decompression (MVD) is the preferred treatment for refractory trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia. Despite its high rate of success, MVD carries risk of complications. In this study, we examine outcomes following MVD and identify risk factors associated with adverse outcomes.

Methods:

A review of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was performed with CPT code 61458 queried between 2007 and 2014. Demographics, preoperative comorbidities, and 30-day outcomes were analyzed. Univariate and multivariate regression analyses were performed to identify predictors of reoperation and adverse events.

Results:

Five hundred and six craniotomies were studied. Nineteen (5.5%) instances of 30-day readmission were reported, with 14 (2.8%) patients returning to the operating room. No instances of death or hemorrhage requiring operation were reported. Morbid obesity (body mass index >40) (P = 0.030) and diabetes (P = 0.017) were associated with risk of reoperation. Age, operative time, and indication for surgery were not associated with significant differences in adverse events.

Conclusions:

MVD is a common and effective procedure with a relatively safe profile and low 30-day risk of reoperation. Advanced age is not associated with worse outcomes. Obesity and diabetes, however, are associated with increased risk of reoperation and may warrant additional precautions.

Long-term outcomes of microvascular decompression and Gamma Knife surgery for trigeminal neuralgia: a retrospective comparison study

BACKGROUND

There is still no clear guideline for surgical treatment for patients with medically refractory trigeminal neuralgia (TN). When it comes to which surgical treatment to choose, microvascular decompression (MVD) or Gamma Knife surgery (GKS), we should know the long-term outcome of each treatment.

METHODS

We analyzed 179 patients undergoing MVD and 52 patients undergoing GKS followed for 1 year or longer. We evaluated the patient's neurological status including pain relief, complications and recurrence. Results were assessed with Barrow Neurological Institute (BNI) pain intensity and facial numbness scores. Overall outcomes were compared between the two groups based on pain relief and complications.

RESULTS

BNI pain intensity and facial numbness scores at the final visit were significantly lower in the MVD group than in the GKS group (P < 0.001, P = 0.04, respectively). Overall outcomes were superior following MVD than following GKS (P < 0.001). Following whichever treatment, there were initially high rates of pain-free status "without medication": 96.6% in the MVD group and 96.2% in the GKS group. However, 6.1% in the MVD group and 51.9% in the GKS group fell into a "with medication" state within median periods of 1.83 and 3.92 years, respectively (P < 0.001). Kaplan-Meier analysis revealed that pain recurred more often and later in the GKS group than in the MVD group (P < 0.001).

CONCLUSIONS

Considering the long-term outcomes, MVD should be chosen as the initial surgical treatment for patients with medically refractory TN.

Microvascular decompression for trigeminal neuralgia in patients with failed gamma knife surgery: Analysis of efficacy and safety

OBJECTIVE

Though it is usually successful, failure or delayed pain recurrence may occur after gamma knife surgery (GKS) in patients with trigeminal neuralgia (TN), and additional intervention may be required. This study aimed to investigate whether the safety and efficacy of microvascular decompression (MVD) were influenced by prior GKS.

PATIENTS AND METHODS

The authors retrospectively evaluated 36 consecutive TN patients who underwent MVD after failed GKS from January 2012 to June 2013. The clinical features, operative findings and surgical outcomes were reviewed and statistically analyzed, and the operation results were further compared with a cohort of 60 patients with no prior GKS.

RESULTS

At surgery, atrophy of the trigeminal nerve was observed in 13 patients (36.1%), arachnoid thickening in 6 patients (16.7%), adhesions between vessels and the trigeminal nerve in 8 patients (22.2%), and atherosclerotic plaque in the offending vessels in 3 patients (8.3%). The complete pain relief rates were 83.3% immediately after MVD and 72.2% at last follow-up, which showed no statistical difference when compared with patients without GKS. New or worsened facial numbness occurred in 7 patients (19.4%), which was significantly higher than those without GKS (p=0.02). Univariate analysis suggested that a positive pain response to the prior GKS correlated with better long-term outcome (p=0.015), and the existence of arachnoid adhesions correlated with higher risk of facial numbness (p=0.03).

CONCLUSIONS

MVD remains an appropriate and effective alternative therapy for patients with failed GKS, with no added technical difficulty. However, the risk of facial numbness seems to be higher than those with MVD alone.

Microvascular Decompression Versus Stereotactic Radiosurgery for Trigeminal Neuralgia: A Decision Analysis

INTRODUCTION

 Both microvascular decompression (MVD) and stereotactic radiosurgery (SRS) have been demonstrated to be effective in treating medically refractory trigeminal neuralgia. However, there is controversy over which one offers more durable pain relief and the patient selection for each treatment. We used a decision analysis model to calculate the health-related quality of life (QOL) for each treatment.

METHODS

 We searched PubMed and the Cochrane Database of Systematic Reviews for relevant articles on MVD or SRS for trigeminal neuralgia published between 2000 and 2015. Using data from these studies, we modeled pain relief and complication outcomes and assigned QOL values. A sensitivity analysis using a Monte Carlo simulation determined which procedure led to the greatest QOL.

RESULTS

MVD produced a significantly higher QOL than SRS at a seven-year follow-up. Additionally, MVD patients had a significantly higher rate of complete pain relief and a significantly lower rate of complications and recurrence.

CONCLUSIONS

With a decision-analytic model, we calculated that MVD provides more favorable outcomes than SRS for the treatment of trigeminal neuralgia.

Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a sudden, severe, brief, stabbing, and recurrent pain within one or more branches of the trigeminal nerve. Type 1 as intermittent and Type 2 as constant pain represent distinct clinical, pathological, and prognostic entities. Although multiple mechanism involving peripheral pathologies at root (compression or traction), and dysfunctions of brain stem, basal ganglion, and cortical pain modulatory mechanisms could have role, neurovascular conflict is the most accepted theory. Diagnosis is essentially clinically; magnetic resonance imaging is useful to rule out secondary causes, detect pathological changes in affected root and neurovascular compression (NVC). Carbamazepine is the drug of choice; oxcarbazepine, baclofen, lamotrigine, phenytoin, and topiramate are also useful. Multidrug regimens and multidisciplinary approaches are useful in selected patients. Microvascular decompression is surgical treatment of choice in TN resistant to medical management. Patients with significant medical comorbidities, without NVC and multiple sclerosis are generally recommended to undergo gamma knife radiosurgery, percutaneous balloon compression, glycerol rhizotomy, and radiofrequency thermocoagulation procedures. Partial sensory root sectioning is indicated in negative vessel explorations during surgery and large intraneural vein. Endoscopic technique can be used alone for vascular decompression or as an adjuvant to microscope. It allows better visualization of vascular conflict and entire root from pons to ganglion including ventral aspect. The effectiveness and completeness of decompression can be assessed and new vascular conflicts that may be missed by microscope can be identified. It requires less brain retraction.

MRI of the Trigeminal Nerve in Patients With Trigeminal Neuralgia Secondary to Vascular Compression

OBJECTIVE

Trigeminal neuralgia is a debilitating facial pain disorder, frequently caused by vascular compression of the trigeminal nerve. Vascular compression that results in trigeminal neuralgia occurs along the cisternal segment of the nerve.

CONCLUSION

Imaging combined with clinical information is critical to correctly identify patients who are candidates for microvascular decompression. The purpose of this article is to review trigeminal nerve anatomy and to provide strategies for radiologists to recognize important MRI findings in patients with trigeminal neuralgia.

Microsurgical treatment of trigeminal neuralgia in patients older than 70 years: An efficacy and safety study

INTRODUCTION

The increasing incidence of trigeminal neuralgia (TN) with age together with population ageing call for reexamination of surgical treatment options for refractory TN in elderly patients.

METHODS

Retrospective review of a consecutive series of patients older than 70 who underwent microvascular decompression (MVD) for refractory TN between 1997 and 2015. Outcomes based on the Barrow Neurological Institute pain intensity score (BNI score) and surgical complications were compared to those of patients younger than 70 undergoing MVD in the same period.

RESULTS

Forty patients older than 70 (mean = 74.8 years) underwent interventions. At a mean follow-up time of 34 months, 73% of the patients presented complete absence of pain without medication (BNI I) and 85% had good pain control with or without medication (BNI I-III). A comparison of these patients with the 85 patients younger than 70 treated surgically during the same period did not find a significant association between age and achievement of pain control (BNI I-II). However, there was a significant association between age older than 70 and complete pain relief (BNI I; P=.03). The mean hospital stay in patients over 70 was also significantly longer (P=.04), although the postsurgical complication rate was similar to that in younger patients.

CONCLUSIONS

Elderly patients with refractory TN may benefit from treatment with MVD and the probability of success and surgical risk are comparable to those in younger patients.

Reversal of insular and microstructural nerve abnormalities following effective surgical treatment for trigeminal neuralgia

Classical trigeminal neuralgia (TN) is a severe neuropathic facial pain disorder commonly associated with neurovascular compression at the trigeminal nerve root entry zone (REZ). Neurosurgical interventions can relieve TN pain, but the mechanisms underlying these effects are unknown. We determined whether the abnormalities we previously reported at the REZ of TN patients using diffusion tensor imaging (DTI) and brain gray matter (GM) analyses resolve after effective neurosurgical treatment. Twenty-five patients who underwent either microvascular decompression surgery or Gamma Knife radiosurgery for right-sided TN had magnetic resonance imaging scans before and after treatment and were compared with age-matched controls. Cortical thickness and voxel-based morphometry examined specific brain GM we previously reported as abnormal in TN. White matter metrics of fractional anisotropy (FA), mean, radial, and axial diffusivities (MD, RD, and AD, respectively) were extracted bilaterally from each trigeminal REZ. Before treatment, patients had widespread GM abnormalities including thinner ventral anterior insula (vAI) cortex, and REZ microstructural abnormalities (lower FA, and higher MD, RD, and AD) compared with controls. We considered a 75% reduction in pain as effective treatment. The right vAI was the only GM region that normalized toward the level of healthy controls after effective treatment. At the REZ, effective treatment reversed FA, MD, RD, and AD abnormalities and was correlated with pain relief after treatment. These results demonstrate that treatment can effectively resolve pain by normalizing REZ abnormalities, which may influence vAI abnormalities. Future studies should consider DTI as an adjunct to assess the patient outcome and subtle microstructural changes after treatment.

Long-term safety and efficacy of Gamma Knife surgery in classical trigeminal neuralgia: a 497-patient historical cohort study

OBJECTIVE

Gamma Knife surgery (GKS) is one of the surgical alternatives for the treatment of drug-resistant trigeminal neuralgia (TN). This study aims to evaluate the safety and efficacy of GKS in a large population of patients with TN with very long-term clinical follow-up.

METHODS

Between July 1992 and November 2010, 737 patients presenting with TN were treated using GKS. Data were collected prospectively and were further retrospectively evaluated at Timone University Hospital. The frequency and severity of pain, as well as trigeminal nerve function, were evaluated before GKS and regularly thereafter. Radiosurgery using the Gamma Knife (model B, C, 4C, or Perfexion) was performed with the help of both MR and CT targeting. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.6 mm (range 4-14 mm) anterior to the emergence of the nerve (retrogasserian target). A median maximum dose of 85 Gy (range 70-90 Gy) was prescribed.

RESULTS

The safety and efficacy are reported for 497 patients with medically refractory classical TN who were never previously treated by GKS and had a follow-up of at least 1 year. The median age in this series was 68.3 years (range 28.1-93.2 years). The median follow-up period was 43.8 months (range 12-174.4 months). Overall, 456 patients (91.75%) were initially pain free in a median time of 10 days (range 1-180 days). Their actuarial probabilities of remaining pain free without medication at 3, 5, 7, and 10 years were 71.8%, 64.9%, 59.7%, and 45.3%, respectively. One hundred fifty-seven patients (34.4%) who were initially pain free experienced at least 1 recurrence, with a median delay of onset of 24 months (range 0.6-150.1 months). However, the actuarial rate of maintaining pain relief without further surgery was 67.8% at 10 years. The hypesthesia actuarial rate at 5 years was 20.4% and at 7 years reached 21.1%, but remained stable until 14 years with a median delay of onset of 12 months (range 1-65 months). Very bothersome facial hypesthesia was reported in only 3 patients (0.6%).

CONCLUSIONS

Retrogasserian GKS proved to be safe and effective in the long term and in a very large number of patients. Even if the probability of long-lasting effects may be modest compared with microvascular decompression, the rarity of complications prompts discussion of using GKS as the pragmatic surgical first- or second-intention alternative for classical TN. However, a randomized trial, or at least a case-matched control study, would be required to compare with microvascular decompression.

Management of Recurrent Trigeminal Neuralgia Associated with Petroclival Meningioma

Objective Petroclival meningioma (PM) presents with trigeminal neuralgia (TN) in < 5% of cases. Neurosurgeons often face the dilemma of formulating a treatment protocol when TN recurs. In this study, we sought to set up a protocol in patients with PM who had a recurrent TN. Materials and Methods We performed a retrospective review of 57 patients with PM. Of the 57 patients, only 7 patients presented with TN, and six patients experienced recurrent TN. The study population was evaluated clinically and radiographically after treatment. Results Overall improvement of pain control after various treatments was 67%, and tumor control was 100%. The pain-free period was 2 years for the Gamma Knife radiosurgery (GKRS) group and 4 years for the resection group when treated as a primary treatment (p = 0.034). Of the six patients, four patients had Barrow Neurosurgical Institute (BNI) score I (no TN, no medication), and two patients had BNI score III (some pain controlled with medication). The Karnofsky performance scale score was significantly improved after treatment compared with the pretreated status (78 versus 88; p = 0.044). Conclusion Microsurgical resection is superior to GKRS in achieving and maintaining pain-free status in patients with recurrent trigeminal pain associated with PM.

Patterns and variations in microvascular decompression for trigeminal neuralgia

Microvascular decompression (MVD) is a highly effective surgical treatment for trigeminal neuralgia (TN). Although there is little prospective clinical evidence, accumulated observational studies have demonstrated the benefits of MVD for refractory TN. In the current surgical practice of MVD for TN, there have been recognized patterns and variations in surgical anatomy and various decompression techniques. Here we provide a stepwise description of surgical procedures and relevant anatomical characteristics, as well as procedural options.

Decreased Probability of Initial Pain Cessation in Classic Trigeminal Neuralgia Treated With Gamma Knife Surgery in Case of Previous Microvascular Decompression

BACKGROUND:

Microvascular decompression (MVD) is the reference technique for pharmacoresistant trigeminal neuralgia (TN).

OBJECTIVE:

To establish whether the safety and efficacy of Gamma Knife surgery for recurrent TN are influenced by prior MVD.

METHODS:

Between July 1992 and November 2010, 54 of 737 patients (45 of 497 with &gt;1 year of follow-up) had a history of MVD (approximately half also with previous ablative procedure) and were operated on with Gamma Knife surgery for TN in the Timone University Hospital. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.6 mm (range, 3.9–11.9 mm) anterior to the emergence of the nerve. A median maximum dose of 85 Gy (range, 70–90 Gy) was delivered.

RESULTS:

The median follow-up time was 39.5 months (range, 14.1–144.6 months). Thirty-five patients (77.8%) were initially pain free in a median time of 14 days (range, 0–180 days), much lower compared with our global population of classic TN (P = .01). Their actuarial probabilities of remaining pain-free without medication at 3, 5, 7, and 10 years were 66.5%, 59.1%, 59.1%, and 44.3%. The hypoesthesia actuarial rate at 1 year was 9.1% and remained stable until 12 years (median, 8 months).

CONCLUSION:

Patients with previous MVD showed a significantly lower probability of initial pain cessation compared with our global population with classic TN (P = .01). The toxicity was low (only 9.1% hypoesthesia); furthermore, no patient reported bothersome hypoesthesia. However, the probability of maintaining pain relief without medication was 44.3% at 10 years, similar to our global series of classic TN (P = .85).

Trigeminal neuralgia due to neurovascular conflicts from venous origin: an anatomical-surgical study (consecutive series of 124 operated cases)

BACKGROUND

Veins as the source of trigeminal neuralgias (TN) lead to controversies. Only a few studies have specifically dealt with venous implication in neurovascular conflicts (NVC). The aim of this study was the anatomical-surgical description of the compressive veins found during micro-vascular decompression (MVD).

METHODS

Patients retained were those in whom a vein was considered compressive, alone, or in association with an artery. The study defined the type of vein involved, its situation along, the location around the root, and management. For this study, denomination of veins in relation with the root was revisited.

RESULTS

Of the 326 consecutive patients who underwent MVD from 2005 to 2013, 124 (38.0 %) had a venous conflict, alone in 29 (8.9 %), or in association with an artery in 95 (29.1 %). The compressive veins belonged to one of the two venous systems described: the superficial or the deep superior petrosal venous system (sSPVS or dSPVS). A vein from sSPVS was found compressive in 81 cases (59.6 %), for the major part it was the pontine affluent of the superior petrosal vein (48 cases). The conflict was situated at TREZ in 28.4 %, mid-cisternal portion in 50.6 %, and porus in 8.6 %. The dSPVS was found compressive in 55 cases (40.4 %), almost always a transverse vein at porus (51 cases). Decompression was coagulation-division of the conflicting vein in 36.8 % and simple cleavage in the other.

CONCLUSIONS

The study shows the frequent implication of veins in NVC as the source of TN. NVC are not only at TREZ but also at mid-cisternal portion and porus of Meckel cave.

Advances in diagnosis and treatment of trigeminal neuralgia

Various drugs and surgical procedures have been utilized for the treatment of trigeminal neuralgia (TN). Despite numerous available approaches, the results are not completely satisfying. The need for more contemporaneous drugs to control the pain attacks is a common experience. Moreover, a number of patients become drug resistant, needing a surgical procedure to treat the neuralgia. Nonetheless, pain recurrence after one or more surgical operations is also frequently seen. These facts reflect the lack of the precise understanding of the TN pathogenesis. Classically, it has been related to a neurovascular compression at the trigeminal nerve root entry-zone in the prepontine cistern. However, it has been evidenced that in the pain onset and recurrence, various neurophysiological mechanisms other than the neurovascular conflict are involved. Recently, the introduction of new magnetic resonance techniques, such as voxel-based morphometry, diffusion tensor imaging, three-dimensional time-of-flight magnetic resonance angiography, and fluid attenuated inversion recovery sequences, has provided new insight about the TN pathogenesis. Some of these new sequences have also been used to better preoperatively evidence the neurovascular conflict in the surgical planning of microvascular decompression. Moreover, the endoscopy (during microvascular decompression) and the intraoperative computed tomography with integrated neuronavigation (during percutaneous procedures) have been recently introduced in the challenging cases. In the last few years, efforts have been made in order to better define the optimal target when performing the gamma knife radiosurgery. Moreover, some authors have also evidenced that neurostimulation might represent an opportunity in TN refractory to other surgical treatments. The aim of this work was to review the recent literature about the pathogenesis, diagnosis, and medical and surgical treatments, and discuss the significant advances in all these fields.

MRI findings in patients with a history of failed prior microvascular decompression for hemifacial spasm: how to image and where to look

BACKGROUND AND PURPOSE

A minority of patients who undergo microvascular decompression for hemifacial spasm do not improve after the first operation. We sought to determine the most common locations of unaddressed neurovascular contact in patients with persistent or recurrent hemifacial spasm despite prior microvascular decompression.

MATERIALS AND METHODS

Eighteen patients with a history of a microvascular decompression presented with persistent hemifacial spasm. All patients underwent thin-section steady-state free precession MR imaging. Fourteen patients underwent repeat microvascular decompression at our institution. Images were evaluated for the following: the presence of persistent vascular compression of the facial nerve, type of culprit vessel (artery or vein), name of the culprit artery, segment of the nerve in contact with the vessel, and location of the point of contact relative to the existing surgical pledget. The imaging findings were compared with the operative findings.

RESULTS

In 12 of the 18 patients (67%), persistent vascular compression was identified by imaging. In 11 of these 12 patients, the culprit vessel was an artery. Compression of the attached segment (along the ventral surface of the pons) was identified in most patients (58%, 7/12). The point of contact was proximal to the surgical pledget in most patients (83%, 10/12). The imaging interpretation was concordant with the surgical results regarding artery versus vein in 86% of cases and regarding the segment of the nerve contacted in 92%.

CONCLUSIONS

In patients with persistent hemifacial spasm despite microvascular decompression, the unaddressed vascular compression is typically proximal to the previously placed pledget, usually along the attached segment of the nerve. Re-imaging with high-resolution T2-weighted MR imaging will usually identify the culprit vessel.