Radiographic evaluation of trigeminal neurovascular compression in patients with and without trigeminal neuralgia

Tobacco Use and Trigeminal Neuralgia: Clinical Features and Outcome After Microvascular Decompression

BACKGROUND AND OBJECTIVES

Tobacco use is known to affect incidence and postoperative outcome for several neurosurgical disorders, but its relationship to trigeminal neuralgia (TN) is not known. We sought to identify unique population characteristics that correlate with tobacco use in a cohort of patients with TN who underwent microvascular decompression (MVD), including effect on long-term postoperative outcome.

METHODS

Data about 171 patients with classic TN treated with MVD were obtained from a prospectively maintained registry. Patients were classified as smokers or nonsmokers based on the use of tobacco within the 6 months before surgery. Analysis of clinical characteristics and postoperative outcome was performed.

RESULTS

Compared with nonsmokers with TN, MVD patients using tobacco were significantly younger (53 vs 62 years, P < .01) and less likely to report pain in a single distribution of the trigeminal nerve (36% vs 65%, P < .01). There was no difference between smokers and nonsmokers in the presence of some degree of continuous pain, severity of neurovascular compression, sex, race, obesity, pain duration before presentation, immediate postoperative outcome, length of stay, or postoperative complication profile. Among 128 patients followed for at least 6 months, smokers were significantly less likely to be pain-free off medications at the last follow-up (36% vs 57%, P < .05).

CONCLUSION

In patients undergoing MVD for TN, smoking is associated with younger age of TN onset, more widespread facial pain, and worse long-term postoperative outcome after MVD. These features suggest that TN in smokers may represent a more severe disease form compared with TN in nonsmokers with different responses to treatment.

Trigeminal neuralgia

Trigeminal neuralgia (TN) is a facial pain disorder characterized by intense and paroxysmal pain that profoundly affects quality of life and presents complex challenges in diagnosis and treatment. TN can be categorized as classical, secondary and idiopathic. Epidemiological studies show variable incidence rates and an increased prevalence in women and in the elderly, with familial cases suggesting genetic factors. The pathophysiology of TN is multifactorial and involves genetic predisposition, anatomical changes, and neurophysiological factors, leading to hyperexcitable neuronal states, central sensitization and widespread neural plasticity changes. Neurovascular compression of the trigeminal root, which undergoes major morphological changes, and focal demyelination of primary trigeminal afferents are key aetiological factors in TN. Structural and functional brain imaging studies in patients with TN demonstrated abnormalities in brain regions responsible for pain modulation and emotional processing of pain. Treatment of TN involves a multifaceted approach that considers patient-specific factors, including the type of TN, with initial pharmacotherapy followed by surgical options if necessary. First-line pharmacological treatments include carbamazepine and oxcarbazepine. Surgical interventions, including microvascular decompression and percutaneous neuroablative procedures, can be considered at an early stage if pharmacotherapy is not sufficient for pain control or has intolerable adverse effects or contraindications.

Efficacy and safety of microvascular decompression with or without partial sensory rhizotomy: a comprehensive meta-analysis and systematic review in treating trigeminal neuralgia

Classical trigeminal neuralgia (TN), caused by vascular compression of the nerve root, is a severe cause of pain with a considerable impact on a patient's quality of life. While microvascular decompression (MVD) has lower recurrence rates when compared with partial sensory rhizotomy (PSR) alone, refractoriness can still be as high as 47%. We aimed to assess the efficacy and safety profile of MVD + PSR when compared to standalone MVD for TN. We searched Medline, Embase, and Web of Science following PRISMA guidelines. Eligible studies included those with ≥ 4 patients, in English, published between January 1980 and December 2023, comparing MVD vs. MVD + PSR for TN. Endpoints were pain cure, immediate post-operative pain improvement, long-term effectiveness, long-term recurrence, and complications (facial numbness, hearing loss, and intracranial bleeding). We pooled odds ratios (OR) with 95% confidence intervals with a random-effects model. I2 was used to assess heterogeneity, and sensitivity and Baujat analysis were conducted to address high heterogeneity. Eight studies were included, comprising a total of 1,338 patients, of whom 1,011 were treated with MVD and 327 with MVD + PSR. Pain cure analysis revealed a lower likelihood of pain cure in patients treated with MVD when compared to patients treated with MVD + PSR (OR = 0.30, 95% CI: 0.13 to 0.72). Immediate postoperative pain improvement assessment revealed a lower likelihood of improvement in the MVD group when compared with the MVD + PSR group (OR = 0.31, 95% CI: 0.10 to 0.95). Facial numbness assessment revealed a lower likelihood of occurrence in MVD alone when compared to MVD + PSR (OR = 0.08, 95% CI: 0.04 to 0.15). Long-term effectiveness, long-term recurrence, hearing loss, and intracranial bleeding analyses revealed no difference between both approaches. Our meta-analysis identified that MVD + PSR was superior to MVD for pain cure and immediate postoperative pain improvement for treating TN. However, MVD + PSR demonstrated a higher likelihood of facial numbness complications. Furthermore, identified that hearing loss and intracranial bleeding complications appear comparable between the two treatments, and no difference between long-term effectiveness and recurrence.

Role of Magnetic Resonance Imaging in the Evaluation of Trigeminal Neuralgia Using Steady-State Imaging

Trigeminal neuralgia (TN) poses diagnostic challenges due to its complex origins, often associated with neurovascular compression. Advanced imaging techniques, particularly magnetic resonance imaging (MRI) with the fast imaging employing steady-state acquisition (FIESTA) sequence, offer crucial insights into TN pathophysiology. This prospective cross-sectional observational study aimed to elucidate MRI's utility in diagnosing TN and correlating imaging findings with clinical manifestations and treatment outcomes. A cohort of 41 patients clinically suspected of TN underwent MRI evaluation at Acharya Vinoba Bhave Rural Hospital, Sawangi (Meghe), Wardha, utilizing various sequences including FIESTA. Analysis revealed a higher incidence among females, predominant unilateral presentation, and a higher prevalence of abnormal MRI findings, with neurovascular compression as the leading etiology. Correlation analysis demonstrated significant associations between facial pain localized to the trigeminal nerve distribution, triggering factors, and abnormal MRI findings. Gender distribution did not significantly influence MRI findings. Treatment outcomes favored microvascular surgery over conservative management in cases of neurovascular compression. This study underscores MRI's pivotal role, particularly FIESTA, in TN evaluation, guiding personalized treatment strategies and emphasizing the importance of integrated clinical and imaging approaches. Further research is warranted to validate these findings and explore additional imaging modalities for a deeper understanding of TN pathogenesis.

Trigeminal Neuralgia as a Primary Demyelinating Disease: Potential Multimodal Evidence and Remaining Controversies

Trigeminal neuralgia is a heterogeneous disorder with likely multifactorial and complex etiology; however, trigeminal nerve demyelination and injury are observed in almost all patients with trigeminal neuralgia. The current management strategies for trigeminal neuralgia primarily involve anticonvulsants and surgical interventions, neither of which directly address demyelination, the pathological hallmark of trigeminal neuralgia, and treatments targeting demyelination are not available. Demyelination of the trigeminal nerve has been historically considered a secondary effect of vascular compression, and as a result, trigeminal neuralgia is not recognized nor treated as a primary demyelinating disorder. In this article, we review the evolution of our understanding of trigeminal neuralgia and provide evidence to propose its potential categorization, at least in some cases, as a primary demyelinating disease by discussing its course and similarities to multiple sclerosis, the most prevalent central nervous system demyelinating disorder. This proposed categorization may provide a basis in investigating novel treatment modalities beyond the current medical and surgical interventions, emphasizing the need for further research into demyelination of the trigeminal sensory pathway in trigeminal neuralgia. PERSPECTIVE: This article proposes trigeminal neuralgia as a demyelinating disease, supported by histological, clinical, and radiological evidence. Such categorization offers a plausible explanation for controversies surrounding trigeminal neuralgia. This perspective holds potential for future research and developing therapeutics targeting demyelination in the condition.

miRNA contributes to neuropathic pains

Neuropathic pain (NP) is a kind of chronic pain caused by direct injury to the peripheral or central nervous system (CNS). microRNAs (miRNAs) are small noncoding RNAs that mostly interact with the 3 untranslated region of messenger RNAs (mRNAs) to regulate the expression of multiple genes. NP is characterized by changes in the expression of receptors and mediators, and there is evidence that miRNAs may contribute to some of these alterations. In this review, we aimed to fully comprehend the connection between NP and miRNA; and also, to establish a link between neurology, biology, and dentistry. Studies have shown that targeting miRNAs may be an effective therapeutic strategy for the treatment of chronic pain and potential target for the prevention of NP.

Proximal trigeminal nerve atrophy is associated with favourable outcomes and persistent facial numbness following percutaneous balloon compression for primary trigeminal neuralgia

OBJECTIVE

Whether nerve atrophy can affect the prognosis of primary trigeminal neuralgia (PTN) patients undergoing percutaneous balloon compression (PBC) remains unclear. This study aimed to determine the association between nerve characteristics observed on preoperative magnetic resonance imaging (MRI) and PBC outcomes.

METHODS

Between January 2019 and December 2022, a cohort of 58 patients with unilateral PTN treated with PBC were analysed retrospectively and included in this study. The relationship between MRI findings, including the proximal and distal nerve cross-sectional areas (CSAs), and favourable pain outcomes (BNI Grades I-III) was analysed through Kaplan‒Meier analysis.

RESULTS

After a mean follow-up period of 23.8 ± 13.0 months (range, 6-50 months), 48 (82.8%) patients with PTN were pain free with or without medication. A smaller proximal CSA ratio (proximal CSA of the affected nerve/proximal CSA of the unaffected nerve) was significantly associated with favourable outcomes. The Kaplan-Meier survival analysis showed that patients with proximal nerve atrophy (proximal CSA ratio ≤ 87% after receiver operating characteristic curve analysis) had a higher estimated 4-year probability of maintaining a favourable outcome than those without nerve atrophy (94.4% vs. 30.8%, p = 0.005). In addition, patients with proximal nerve atrophy were more likely to suffer from postoperative persistent facial numbness.

CONCLUSIONS

Proximal nerve atrophy is correlated with both favourable outcomes and persistent facial numbness following PBC. Prospective studies are required to determine the optimal duration and pressure of balloon compression in relation to the proximal CSA ratio to achieve better pain outcomes and less facial numbness.

A New Finding on Magnetic Resonance Imaging for Diagnosis of Hemifacial Spasm with High Accuracy and Interobserver Correlation

Among patients with clinical hemifacial spasm (HFS), imaging exams aim to identify the neurovascular conflict (NVC) location. It has been proven that the identification in the preoperative exam increases the rate of surgical success. Despite the description of specific magnetic resonance image (MRI) acquisitions, the site of neurovascular compression is not always visualized. The authors describe a new MRI finding that helps in the diagnosis of HFS, and evaluate the sensitivity, specificity, and interobserver correlation of the described sign. A cross-sectional study including cases of hemifacial spasm treated surgically from 1 August 2011 to 31 July 2021 was performed. The MRIs of the cases were independently evaluated by two experienced neuroradiologists, who were blinded regarding the side of the symptom. The neuroradiologists were assigned to evaluate the MRIs in two separate moments. Primarily, they evaluated whether there was a neurovascular conflict based on the standard technique. Following this initial analysis, the neuroradiologists received a file with the description of the novel sign, named Prevedello Sign (PS). In a second moment, the same neuroradiologists were asked to identify the presence of the PS and, if it was present, to report on which side. A total of 35 patients were included, mostly females (65.7%) with a mean age of 59.02 (+0.48). Since the 35 cases were independently evaluated by two neuroradiologists, a total of 70 reports were included in the analysis. The PS was present in 66 patients (sensitivity of 94.2%, specificity of 91.4% and positive predictive value of 90.9%). When both analyses were performed in parallel (standard plus PS), the sensitivity increased to 99.2%. Based on the findings of this study, the authors conclude that PS is helpful in determining the neurovascular conflict location in patients with HFS. Its presence, combined with the standard evaluation, increases the sensitivity of the MRI to over 99%, without increasing risks of harm to patients or resulting in additional costs.

A Systematic Review of the Role of Magnetic Resonance Imaging in the Diagnosis and Detection of Neurovascular Conflict in Patients With Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a debilitating disorder causing severe, episodic, unilateral stabbing facial pain disturbing enough to disrupt the activities of daily life. Classic TN is caused due to compression injury of the trigeminal nerve at the cistern segment caused by either an artery or a vein, referred to as neurovascular contact or conflict (NVC). Magnetic resonance imaging (MRI) has been the standard tool for the diagnosis of NVC. This study aimed to determine the incidence of NVC in TN, as identified by MRI, assess the various MRI grading patterns among patients with TN, and identify the vessels primarily involved in NVC. A systematic search of studies that used MRI for the diagnosis of TN in reference to NVC was conducted on DOAJ and PubMed/PubMed Central. Data were extracted and entered into a Microsoft Excel spreadsheet. The outcomes measured were the incidence of NVC as shown in MRI, vessels involved in NVC, and MRI grading patterns. We identified and selected 20 studies that fulfilled inclusion/exclusion criteria. In total, 1,436 patients were enrolled in all included studies. The type of MRI used was 1.5 T or 3 T MRI. The mean age of the patients varied from 49 to 63 years, with an equivalent male-to-female ratio. NVC was seen in 1,276 cases out of 1,436 cases (88.85%) of TN on the ipsilateral side, as shown by MRI. The vessels involved were arteries in 80-90% of the cases, followed by veins. Among the arteries, the superior cerebellar artery was the most common artery (80-90% of cases). The grades of NVC as assessed by MRI included grades I, II, and III with varied proportions in different studies. NVC is a common problem in TN, wherein there is compression at the nerve root entry zone, and it shows a strong predilection for the elderly population. MRI seems to be a novel imaging diagnostic investigation to identify NVC associated with TN. Moreover, NVC grading must be done with MRI so that it may help the surgeon in stratifying the patient's treatment.

Increase in Trigeminal Nerve Cross-Sectional Area on Immediate Postoperative MRI Predicts Favorable Outcome After Microvascular Decompression for Classical Trigeminal Neuralgia

BACKGROUND

Although distortion or indentation of a trigeminal nerve due to neurovascular compression (NVC) is associated with classical trigeminal neuralgia, whether morphological change in the trigeminal nerve is relieved by eliminating NVC has not been studied.

OBJECTIVE

To estimate morphological change in the trigeminal nerve after microvascular decompression (MVD).

METHODS

Fifty patients with classical trigeminal neuralgia who underwent MVD were included. Using coronal images in both preoperative and postoperative MRI, the trigeminal nerve cross-sectional area (CSA) was measured at 4 mm anterior to the nerve entry into the pons. Clinical outcomes were assessed using the Barrow Neurological Institute Pain Intensity Scale (BNI-PS) at the patient's latest follow-up.

RESULTS

Forty-one patients achieved favorable outcomes without medication (BNI-PS I or II), and 9 patients had residual pain (BNI-PS ≥ 3A). The mean symptomatic trigeminal nerve CSA was increased by 51.47% after MVD in the favorable outcome group (preoperative: 4.37 ± 1.64 mm 2 vs postoperative: 6.26 ± 1.76 mm 2 , P < .01), whereas it was not significantly changed in the unfavorable outcome group (preoperative: 4.20 ± 1.19 mm 2 vs postoperative: 4.43 ± 1.24 mm 2 , P = .69). Kaplan-Meier survival analysis showed that the 3-year probability of maintaining a favorable outcome was 92.3 ± 7.4% and 56.1 ± 11.9%, for those whose symptomatic trigeminal nerve CSA was increased by over 20% and less than 20%, respectively ( P < .01).

CONCLUSION

Morphological changes in the trigeminal nerve due to NVC could be recovered by MVD, and increases in the trigeminal nerve CSA predicted favorable outcomes.

A study to evaluate neurovascular conflict of trigeminal nerve in trigeminal neuralgia patients with the help of 1.5 T MR imaging

Introduction

Trigeminal neuralgia is a neuropathic pain that occurs in the sensory supply region of the trigeminal nerve (V cranial nerve). The common etiology of trigeminal neuralgia is said to be vascular compression on the trigeminal nerve root. In our day-to-day practice, we see many asymptomatic patients having vascular loops around the trigeminal nerve root. We undertook this study to see the significance of nerve root compression by the vascular loop as a cause for trigeminal neuralgia.

Materials and methods

A total of 67 classical trigeminal neuralgia patients with NVC involving the trigeminal nerve as diagnosed on MRI brain sequences including FIESTA sequence were included in the study. NVC in all the patients were studied for the side, site of neurovascular contact of cisternal segment of the trigeminal nerve from the brainstem, deviation of nerve at NVC, atrophy of nerve, nature and origin of vascular loop causing NVC and correlated with TGN symptoms.

Results

Out of 67 patients studied, all of them (100%) had NVC on ipsilateral side and 26 patients (34%) had NVC at contralateral trigeminal nerve. Incidence of trigeminal neuralgia was most commonly seen between the 41 and 60 years age (64%) followed by 61–80 years with mean age of 55.6 years. Incidence in females (64%) was found to be more common than in males (35%). NVC was observed at the root entry zone (< 7 mm from brain stem) in 63 trigeminal nerves on symptomatic side and 5 trigeminal nerves on the asymptomatic side. NVC occurring at REZ on symptomatic side was found to be statistically significant with P < 0.001. Mean distance of NVC from brain stem at symptomatic side was 3.4 mm and was 8.4 mm in asymptomatic side NVCs. Atrophy was seen in 8 trigeminal nerves, all on symptomatic side and NVC occurring at root entry zone. No displacement of nerve root at the point of neurovascular contact was observed in our study. Most common vessel causing was found to be ipsilateral superior cerebellar artery followed by the ipsilateral anterior inferior cerebellar artery.

Conclusions

Neurovascular contact of trigeminal nerve occurring at the nerve root entry zone has a strong association with ipsilateral trigeminal neuralgia symptoms. In addition, the presence of the trigeminal nerve thinning is also associated with ipsilateral trigeminal neuralgia. With the increase in age, there are higher chances of association of NVC with ipsilateral trigeminal neuralgia symptoms.

Three-Dimensional Constructive Interference in Steady State (3D CISS) Imaging and Clinical Applications in Brain Pathology

Three-dimensional constructive interference in steady state (3D CISS) is a steady-state gradient-echo sequence in magnetic resonance imaging (MRI) that has been used in an increasing number of applications in the study of brain disease in recent years. Owing to the very high spatial resolution, the strong hyperintensity of the cerebrospinal fluid signal and the high contrast-to-noise ratio, 3D CISS can be employed in a wide range of scenarios, ranging from the traditional study of cranial nerves, the ventricular system, the subarachnoid cisterns and related pathology to more recently discussed applications, such as the fundamental role it can assume in the setting of acute ischemic stroke, vascular malformations, infections and several brain tumors. In this review, after briefly summarizing its fundamental physical principles, we examine in detail the various applications of 3D CISS in brain imaging, providing numerous representative cases, so as to help radiologists improve its use in imaging protocols in daily clinical practice.

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.

Predictability of Fused 3D-T2-SPACE and 3D-TOF-MRA Images in Identifying Conflict in Trigeminal Neuralgia

Purpose

To evaluate the efficacy of fused three-dimensional T2 sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) and three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) sequences for detecting neurovascular compression (NVC) in patients presenting with trigeminal neuralgia (TN).

Methods

A prospective study was carried in 33 consecutive patients (m/f: 17/16; mean age, 56.3 ± 10.4 years) with unilateral TN confirmed NVC and consensus by two experienced radiologists on fused 3D-SPACE and 3D-TOF-MRA sequences of 3-tesla (3-T) MRI. All patients underwent microvascular decompression (MVD), using photos and video in surgery as documents compared with MRI. Both the MRI and MVD were reported for three grades (contact, compression, distortion), vessel types (artery or vein), identification of offending vessel, site (juxtapontine, cisternal, and juxtapetrous), and location (cranial, caudal, medial, lateral). Agreement between preoperative MRI visualization and surgical findings was assessed using the kappa (K) statistic.

Results

The k-values for the agreement were excellent for the grade of NVC (k=0.82), vessel types (k=0.78), and location of conflict (k=0.74), and good for identification of the offending vessel (0.65) and the site-affected vessel (k=0.69).

Conclusion

The fused D3-SPACE and 3D-TOF-MRA images are highly effective tools for the evaluation and treatment planning of NVC in TN patients.

The changing face of trigeminal neuralgia-A narrative review

OBJECTIVE

This narrative review aims to update the reader on the new classification of trigeminal neuralgia (TN), clinical signs, pathophysiologic evidence, and their implications on management. This review is based on the authors' collective experience and knowledge of the literature in addition to a literature search.

BACKGROUND

In recent years, the phenotype of TN has been intensively studied leading to discrete groups of patients. These include patients with TN with additional continuous pain, and patients with and without neurovascular compression of the trigeminal dorsal root entry zone. A number of associated clinical signs such as tearing and sensory changes need further research.

METHODS

The literature on TN was searched in PubMed with the aims of providing evidence for the recently published third edition of the International Classification of Headache Disorders (ICHD) and update the clinical phenotype and management of the TN subcategories.

RESULTS

The ICHD's new classification for TN is based on reliable clinical data, imaging, and neurophysiologic studies. The TN classification reflects current knowledge and has improved the possibility for clinicians to choose adequate management options. However, there is a lack of effective, safe drugs for the management of TN and sparse, robust data on neurosurgical options.

CONCLUSION

Research into all aspects of TN-diagnosis, pharmacotherapy, surgery, long-term management prognosis, and natural history-is needed. Research should adhere to the ICHD's schema for TN. Improved drugs are needed along with rigorous research into surgical options and their efficacy for different subtypes of TN.

Trigeminal neuralgia diffusivities using Gaussian process classification and merged group tractography

ABSTRACT

Imaging of trigeminal neuralgia (TN) has demonstrated key diffusion tensor imaging-based diffusivity alterations in the trigeminal nerve; however, imaging has primarily focused on the peripheral nerve segment because of previous limitations in reliably segmenting small fiber bundles across multiple subjects. We used Selective Automated Group Integrated Tractography to study 36 subjects with TN (right-sided pain) and 36 sex-matched controls to examine the trigeminal nerve (fifth cranial nerve [CN V]), pontine decussation (TPT), and thalamocortical fibers (S1). Gaussian process classifiers were trained by scrolling a moving window over CN V, TPT, and S1 tractography centroids. Fractional anisotropy (FA), generalized FA, radial diffusivity, axial diffusivity, and mean diffusivity metrics were evaluated for both groups, analyzing TN vs control groups and affected vs unaffected sides. Classifiers that performed at greater-than-or-equal-to 70% accuracy were included. Gaussian process classifier consistently demonstrated bilateral trigeminal changes, differentiating them from controls with an accuracy of 80%. Affected and unaffected sides could be differentiated from each other with 75% accuracy. Bilateral TPT could be distinguished from controls with at least 85% accuracy. TPT left-right classification achieved 98% accuracy. Bilateral S1 could be differentiated from controls, where the affected S1 radial diffusivity classifier achieved 87% accuracy. This is the first TN study that combines group-wise merged tractography, machine learning classification, and analysis of the complete trigeminal pathways from the peripheral fibers to S1 cortex. This analysis demonstrates that TN is characterized by bilateral abnormalities throughout the trigeminal pathway compared with controls and abnormalities between affected and unaffected sides. This full pathway tractography study of TN demonstrates bilateral changes throughout the trigeminal pathway and changes between affected and unaffected sides.

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

BACKGROUND

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 (Elekta AB, 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 VI-V) 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 proximal NVC are not predictive of GKS outcomes. Future studies are required to determine optimal treatments for long-term pain relief in patients with CTN and trigeminal nerve atrophy.

The Spectrum of Trigeminal Neuralgia Without Neurovascular Compression

BACKGROUND

In trigeminal neuralgia type 1 (TN1), neurovascular compression (NVC) is often assumed to be the pain initiating mechanism. NVC can be surgically addressed by microvascular decompression (MVD). However, some patients with TN1 present without NVC (WONVC).

OBJECTIVE

To characterize and analyze the clinical spectrum of a TN1 patient population WONVC.

METHODS

A retrospective chart review of patients presenting with TN1 between 2007 and 2017 was performed. Patients who were potential candidates for MVD surgery underwent high-resolution imaging with 3-dimensional (3D) reconstruction to address the presence, or absence, of NVC. Demographic data about the populations with NVC (WNVC) and WONVC were collected.

RESULTS

Of 242 patients with TN1, 32% did not have NVC. Patients WONVC were on average 10.6 yr younger than those WNVC. TN1 onset in patients WONVC was more frequent below 48.7 yr, and the opposite was found in patients WNVC. Compared to patients WNVC, those WONVC were predominantly female (odds ratio 4.8), on average were 4 yr younger at symptom onset (34.7 yr) and 7.8 yr younger at first clinic visit, and had a 3.7 yr shorter symptom duration.

CONCLUSION

Patients presenting with TN1 WONVC were predominantly females in their mid-30s with short symptom duration. In the absence of NVC, this subgroup of TN1 patients has limited surgical options, and potentially a longer condition duration that must be managed medically or surgically. This population WONVC might provide insights into the true pathophysiology of TN1.

Trigeminal Nerve Compression Without Trigeminal Neuralgia: Intraoperative vs Imaging Evidence

BACKGROUND

While high-resolution imaging is increasingly used in guiding decisions about surgical interventions for the treatment of trigeminal neuralgia, direct assessment of the extent of vascular contact of the trigeminal nerve is still considered the gold standard for the determination of whether nerve decompression is warranted.

OBJECTIVE

To compare intraoperative and magnetic resonance imaging (MRI) findings of the prevalence and severity of vascular compression of the trigeminal nerve in patients without classical trigeminal neuralgia.

METHODS

We prospectively recruited 27 patients without facial pain who were undergoing microvascular decompression for hemifacial spasm and had undergone high-resolution preoperative MRI. Neurovascular contact/compression (NVC/C) by artery or vein was assessed both intraoperatively and by MRI, and was stratified into 3 types: simple contact, compression (indentation of the surface of the nerve), and deformity (deviation or distortion of the nerve).

RESULTS

Intraoperative evidence of NVC/C was detected in 23 patients. MRI evidence of NVC/C was detected in 18 patients, all of whom had intraoperative evidence of NVC/C. Thus, there were 5, or 28% more patients in whom NVC/C was detected intraoperatively than with MRI (Kappa = 0.52); contact was observed in 4 of these patients and compression in 1 patient. In patients where NVC/C was observed by both methods, there was agreement regarding the severity of contact/compression in 83% (15/18) of patients (Kappa = 0.47). No patients exhibited deformity of the nerve by imaging or intraoperatively.

CONCLUSION

There was moderate agreement between imaging and operative findings with respect to both the presence and severity of NVC/C.

Trigeminal neuralgia associated with multiple sclerosis: A multimodal assessment of brainstem plaques and response to Gamma Knife radiosurgery

BACKGROUND

Gamma Knife radiosurgery (GKRS) is a minimally invasive procedure for trigeminal neuralgia secondary to multiple sclerosis (MS-TN). Patients with MS-TN experience suboptimal response rates to treatment, and the relationship between trigeminal microstructure and treatment outcome is poorly understood.

OBJECTIVE

To characterize imaging features of MS-TN pain and GKRS response.

METHODS

3 T diffusion-weighted imaging (DWI), T1-w, T2-w, and fluid-attenuated inversion recovery (FLAIR) sequences were acquired for 18 MS-TN patients undergoing GKRS. Brainstem plaques were standardized into a common space to determine plaque distribution. Ratio of T1-w/T2-w or "myelin maps (MM)" was generated. Multi-tensor tractography was used to delineate the radiosurgical target (RT), root entry zone (REZ), and proximal pontine segment (PPS) of the trigeminal nerves.

RESULTS

Laterality of MS-TN is associated with increased axial diffusivity at the PPS, whereas decreased MM at the PPS correlated with poor GKRS response. Preoperatively, GKRS responders have higher fractional anisotropy at the RT, higher axial diffusivity at the REZ, and higher MM intensities at the PPS.

CONCLUSION

This study demonstrates that diffusivities and MM intensities are important correlates of pain and treatment response, respectively. Overall, preoperative multimodal assessment of the central trigeminal pathway is a better indicator of GKRS response than postoperative assessment of the reduction in fractional anisotropy peripherally.

Computational Fluid Dynamics Analysis of the Offending Artery at Sites of Neurovascular Compression in Trigeminal Neuralgia Using Preoperative MRI Data

This study aimed to analyze the hemodynamic features of the offending artery at sites of neurovascular compression (NVC) using computational fluid dynamics (CFD). A total of 23 patients who underwent microvascular decompression (MVD) for primary trigeminal neuralgia (TN) between January 2015 and December 2016 were enrolled in this study. The compressing vessel at the NVC site was identified microsurgically in all cases, and patients were divided into two groups based on the intraoperative findings: (1) the arterial NVC group and (2) the non-arterial NVC control group. A 3D surface model of the structures surrounding the NVC was created using preoperative magnetic resonance imaging (MRI), and CFD analysis was performed for the target artery. In addition to standard parameters, such as the wall shear stress (WSS), flow velocity, and pressure, we calculated the WSS ratio (WSSR) by dividing the WSS at the NVC by the mean WSS of the target. Arterial compression was observed intraoperatively in 13 patients. The mean WSSR of the arterial NVC group was significantly higher than that of the control group (2.36 ± 1.00 vs. 1.18 ± 0.73, P <0.05). There were no significant intergroup differences in the other calculated parameters. High WSSR, which indicates elevated WSS at the sites of NVC, was identified as a unique parameter of arterial compression that may contribute to TN. CFD could be a useful clinical tool in determining the target of MVD under preoperative conditions.

Development and Evaluation of a Preoperative Trigeminal Neuralgia Scoring System to Predict Long-Term Outcome Following Microvascular Decompression

BACKGROUND

Microvascular decompression (MVD) can be an effective intervention for trigeminal neuralgia (TN); however, an optimal system for patient selection and surgical outcome prediction has not been defined.

OBJECTIVE

To develop and validate a preoperative TN grading system for the prediction of long-term pain relief after MVD.

METHODS

This retrospective cohort study included consecutive patients suffering unilateral TN who underwent MVD with &gt;18-mo follow-up. A grading system was formulated using 3 previously validated preoperative characteristics. The primary end-point was long-term, pain-free status without use of medication. Ability to predict pain-free status was analyzed by multiple regression and assessed by area under the receiver operating characteristic curve (AUC). Clinical utility to predict MVD success and reduce unnecessary surgeries was assessed by decision-curve analysis.

RESULTS

Of 208 patients analyzed, 73% were pain-free without medication at &gt;18-mo follow-up. Pain-free status was predicted by classical TN type, positive response to carbamazepine and/or oxcarbazepine, and presence and nature of neurovascular compression demonstrated on MRI (all P &lt; .01). The TN grading system demonstrated good discriminatory ability for prediction of pain-free status (AUC 0.85, 95% CI 0.80-0.91). Decision-curve analysis demonstrated a net reduction of 20 cases likely to be unsuccessful per 100 patients evaluated with this grading system above a decision threshold of 80%.

CONCLUSION

This TN grading system reliably predicts long-term pain-free status without medications following MVD. The use of the TN grading system as part of a comprehensive work-up may reduce the number of unsuccessful operations.

Trigeminal nerve and white matter brain abnormalities in chronic orofacial pain disorders

Medial temporal lobe activity is investigated in meta-analyses of experimental and chronic pain. Abnormal hippocampal connectivity is found in patients with chronic low back pain.

The orofacial region is psychologically important, given that it serves fundamental and important biological purposes. Chronic orofacial pain disorders affect the head and neck region. Although some have clear peripheral etiologies, eg, classic trigeminal neuralgia, others do not have a clear etiology (eg, muscular temporomandibular disorders). However, these disorders provide a unique opportunity in terms of elucidating the neural mechanisms of these chronic pain conditions: both the peripheral and central nervous systems can be simultaneously imaged. Diffusion-weighted imaging and diffusion tensor imaging have provided a method to essentially perform in vivo white matter dissections in humans, and to elucidate abnormal structure related to clinical correlates in disorders, such as chronic orofacial pains. Notably, the trigeminal nerve anatomy and architecture can be captured using diffusion imaging. Here, we review the trigeminal somatosensory pathways, diffusion-weighted imaging methods, and how these have contributed to our understanding of the neural mechanisms of chronic pain disorders affecting the trigeminal system. We also discuss novel findings indicating the potential for trigeminal nerve diffusion imaging to develop diagnostic and precision medicine biomarkers for trigeminal neuralgia. In sum, diffusion imaging serves both an important basic science purpose in identifying pain mechanisms, but is also a clinically powerful tool that can be used to improve treatment outcomes.

Update on Trigeminal Neuralgia

PURPOSE OF REVIEW

To review current treatments for trigeminal neuralgia, with an emphasis on determining which patients may benefit from neurosurgical procedures.

RECENT FINDINGS

A detailed history is the most helpful tool for diagnosing trigeminal neuralgia (TN) and predicting response to neurosurgical treatments. Patients with classic trigeminal neuralgia will describe severe, unilateral, intermittent facial pain that is triggered by innocuous sensory stimuli. In most cases, pain is caused by compression of the trigeminal nerve by a blood vessel near the brainstem. Magnetic resonance imaging is necessary to rule out TN secondary to multiple sclerosis or tumor. Modern high-resolution T2 images may demonstrate neurovascular contact, particularly when analyzed by a neurosurgeon with expertise in TN. Initial management involves a trial of medication, usually carbamazepine or oxcarbazepine. Microvascular decompression (MVD) is safe and effective surgery, for patients with classic TN related to neurovascular compression. For patients with TN secondary to multiple sclerosis, and for patients who are otherwise poor candidates for MVD, neurosurgical options include percutaneous trigeminal rhizotomy and radiosurgery. Neurosurgical procedures are less effective in relieving atypical facial pain. In the clinical evaluation of a patient with facial pain, it is important to distinguish classic trigeminal neuralgia from atypical facial pain. A patient with classic trigeminal neuralgia would benefit from neurosurgical consultation. The advent of high-resolution MRI and MRA sequences now allows a neurosurgeon to detect when neurovascular compression is likely, and select the optimal procedure for treatment.

Dementia: Paradigm shifting into high gear

Redressing the rising threat of dementia demands not only an increase, but a diversification of efforts. We need new approaches, trials, and partners. We cannot afford to continue to only round up the usual suspects, β amyloid, and tau and try to stop them with a single drug "silver bullet". Dementia of late onset is not a disease, but an amalgam of interactive pathologies on the shifting background of aging, requiring multimodal targeting. Cerebrovascular diseases coexist and coact with all major neurodegenerative pathologies, increasing two-fold the likelihood that they will manifest clinically. Cerebrovascular diseases need to be controlled, to give antidegenerative drugs a chance to succeed. This calls for new types of trials and designs. Stroke doubles the chances of developing dementia and decreases in stroke incidence correlate with decreases in dementia. Ninety percent of strokes are potentially preventable and so are a proportion of dementias. The stroke and dementia communities need to partner and complement the search for silver bullets with the golden opportunity of doing something now.

Correlation between nerve atrophy, brain grey matter volume and pain severity in patients with primary trigeminal neuralgia

BACKGROUND

Recent neuroimaging studies have reported grey matter alterations in primary trigeminal neuralgia patients. However, few studies have focused on quantitative measurements of trigeminal nerves and the interaction between trigeminal nerve volume and brain morphology, particularly grey matter volume. In this study, we investigated the link between trigeminal nerves and grey matter volume changes in primary trigeminal neuralgia patients compared to healthy controls. Moreover, we explored the association of structure of trigeminal nerves and grey matter to collected pain clinical variables.

METHODS

Eighty participants (40 patients and 40 controls) were recruited for the study. All participants underwent MRI sessions and clinical pain assessment. Trigeminal nerve volume and whole brain grey matter volume were evaluated using quantitative imaging techniques. Sensory and affective pain rating indices were assessed using the visual analog scale and short-form McGill Pain Questionnaire. Mediation analysis was conducted to investigate the relationship between clinical pain variables and volumetric changes in trigeminal nerves and grey matter.

RESULTS

Decreased trigeminal nerve volume was detected in primary trigeminal neuralgia patients compared to controls. Additionally, reduced grey matter volume was found in several regions associated with pain in primary trigeminal neuralgia subjects, including the insula, secondary somatosensory cortex, hippocampus, dorsal anterior cingulate cortex, precuneus, and several areas of the temporal lobe. Mediation analysis revealed that decreased trigeminal nerve volume drove grey matter volume abnormality of the left insula, and further led to increased pain ratings.

CONCLUSION

This study showed a predominantly direct effect of trigeminal nerve atrophy on clinical pain variables in primary trigeminal neuralgia patients, providing new insight into the pathophysiology of the disease.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT02713646.

Contemporary concepts of pain surgery

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.

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

BACKGROUND AND PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Reliability of MRI for predicting characteristics of neurovascular conflicts in trigeminal neuralgia: implications for surgical decision making

OBJECTIVE

The choice of microvascular decompression (MVD), among the several other surgical options, for treating refractory classical trigeminal neuralgia (TN) relies mostly on preoperative imaging, but the degree of reliability of MRI remains a matter of debate. The authors approached the question of predictability of neurovascular conflict (NVC) in a series of 100 protocolized MRI studies from patients with TN who underwent MVD, by reexamination of MR images, blinded to the clinical data and surgical findings, including the side of the neuralgia.

METHODS

Patients included in the study were those who underwent MVD after surgical indication had been determined based on a protocolized imagery workup (3D high-resolution T2-weighted cisternography centered on the trigeminal nerve, 3D time-of-flight angiography, and 3D gadolinium-enhanced T1-weighted imaging) performed at our institution. All MR images were blindly reexamined, and neurovascular relationships were described on both sides, noting the existence of compression, vessels involved, situation along the root, and degree of compression. The results of MRI evaluation were then compared with actual surgical findings. The extent of agreement and quality of the prediction were expressed with Cohen's kappa coefficient (κ) and receiver operating characteristic (ROC) statistics.

RESULTS

A conflict had actually been found during surgery in 94 of 100 patients. The sensitivity of MRI to detect a conflict was 97% and the specificity was 50%. Vessel type was identified with high reliability (κ = 0.80), while the grade of the conflict and its situation along the root showed poor to average reliability (κ = 0.38 and κ = 0.40, respectively). The area under the ROC curve for predicting the presence of a conflict according to the grades of conflict seen on MRI was 0.93, which is considered very good. The positive predictive value was differentiated according to the grade of conflict, with a very high value for high grades of vascular conflict.

CONCLUSIONS

This study shows an overall good reliability of MRI to predict the existence of an NVC. The prediction value is excellent for high grades of compression. Some apparent low-grade compressions on MRI may be revealed as false positives in surgical exploration. This raises the question of what other imaging methods might be used to determine not only the existence of a conflict but also its degree of compression. The degree of compression is of paramount importance to predict the probability of long-term pain relief, and therefore in the decision to propose MVD as the first choice of surgical treatment.

Absence of neurovascular conflict during microvascular decompression while treating essential trigeminal neuralgia. How to proceed? Systematic review of literature

INTRODUCTION

Neurovascular conflict is the most accepted hypothesis for the cause for trigeminal neuralgia. Microvascular decompression of the trigeminal nerve is the most common surgical treatment for these patients. However, despite advances in diagnostic techniques, neurovascular conflict is sometimes not detected during surgery. The aim of this paper is to systematically review all the options available to best manage this scenario.

RESULTS

Several techniques that could be used during microvascular decompression for trigeminal neuralgia in the absence of neurovascular conflict have been described. The success rates of these techniques, pain recurrence rates and rates of complications are also reported. Finally, we provide suggestions based on our experience.

CONCLUSIONS

There is no gold standard, but several techniques could be successfully used in the absence of neurovascular conflict. The use of destructive techniques, such as PSR, should be held as treatments of last resort.

Prognostic Impact and Post-operative Evaluation of Volumetric Measurement of the Cerebellopontine Cistern in Trigeminal Neuralgia Using 3 Tesla Magnetic Resonance Imaging

The aim of this study was to evaluate the importance of pre- and post-operative volumetric measurement of the cerebellopontine angle (CPA) using 3 Tesla (3T) magnetic resonance imaging (MRI). Between April 2012 and December 2015, a total of 87 consecutive patients underwent microvascular decompression (MVD) for trigeminal neuralgia (TN), of whom 51 with primary TN caused by arterial compression were enrolled in this study. Bilateral CPA cistern volume was evaluated using 3T MRI before and after surgery; the Cistern Deviation Index was used to represent the degree of deviation of the CPA cistern. The relationships between CPA cistern volume and the etiology of TN were assessed, and post-operative changes in anatomical parameters were examined to determine differences between recurrent and non-recurrent patients with TN. The mean volume of the CPA cistern on the affected side was significantly smaller than the unaffected side (P < 0.001). Five of 51 (10%) patients experienced TN recurrence. The recurrent cases demonstrated significantly lower pre-operative Cistern Deviation Index scores than non-recurrent cases (P = 0.035). On the unaffected side-but not the affected side-post-operative volume reduction was significantly greater in the recurrence group than in the non-recurrence group (P = 0.004). The pre-operative Cistern Deviation Index was a useful parameter to predict the recurrence of TN. In recurrent patients, post-operative inflammatory reaction may extend to not only the operated side but also the healthy side and reduce the volume of the CPA cistern.

Anterior Inferior Cerebellar Arteries Juxtaposed with the Internal Acoustic Meatus and Their Relationship to the Cranial Nerve VII/VIII Complex

Vascular loops in the cerebellopontine angle (CPA) and their relationship to cranial nerves have been used to explain neurological symptoms. The anterior inferior cerebellar artery (AICA) has variable branches producing vascular loops that can compress the facial cranial nerve (CN) VII and vestibulocochlear (CN VIII) nerves. AICA compression of the facial-vestibulocochlear nerve complex can lead to various clinical presentations, including hemifacial spasm (HFS), tinnitus, and hemiataxia. The formation of arterial loops inside or outside of the internal auditory meatus (IAM) can cause abutment or compression of CN VII and CN VIII. Twenty-five (50 sides) fresh adult cadavers underwent dissection of the cerebellopontine angle in the supine position. In regard to relationships between the AICA and the nerves of the facial/vestibulocochlear complex, 33 arteries (66%) traveled in a plane between the facial/nervus intermedius nerves and the cochlear and vestibular nerves. Five arteries (10%) traveled below the CN VII/VIII complex, six (12%) traveled posterior to the nerve complex, four (8%) formed a semi-circle around the upper half of the nerve complex, and two (4%) traveled between and partially separated the nervus intermedius and facial nerve proper. Our study found that the majority of AICA will travel in a plane between the facial/nervus intermedius nerves and the cochlear and vestibular nerves. Although the relationship between the AICA and porus acusticus and AICA and the nerves of the CN VII/VIII complex are variable, based on our findings, some themes exist. Surgeons should consider these with approaches to the cerebellopontine angle.

Endoscopic versus microscopic microvascular decompression for trigeminal neuralgia: equivalent pain outcomes with possibly decreased postoperative headache after endoscopic surgery

OBJECTIVE

Endoscopic surgery has revolutionized surgery of the ventral skull base but has not yet been widely adopted for use in the cerebellopontine angle. Given the relatively normal anatomy of the cerebellopontine angle in patients with trigeminal neuralgia (TN), the authors hypothesized that a fully endoscopic microvascular decompression (E-MVD) might provide pain outcomes equivalent to those of microscopic MVD (M-MVD) but with fewer complications.

METHODS

The authors conducted a single-institution, single-surgeon retrospective study with patients treated in the period of 2006–2013. Before surgery, all patients completed a questionnaire that included a validated multidimensional pain-outcome tool, the Penn Facial Pain Scale (PFPS, formerly known as Brief Pain Inventory–Facial), an 11-point scale that measures pain intensity, interference with general activities of daily living (ADLs), and facial-specific ADLs. Using a standardized script, independent research assistants conducted follow-up telephone interviews.

RESULTS

In total, 167 patients were available for follow-ups (66.5% female; 93 patients underwent M-MVD and 74 underwent E-MVD). Preoperative characteristics (i.e., TN classification, PFPS components, and medication use) were similar for the 2 surgical groups except for 2 variables. Patients in the M-MVD group had slightly higher incidence of V3 pain, and the 2 groups differed in the date of surgery and hence in the length of follow-up (2.4 years for the M-MVD group and 1.3 years for the E-MVD group, p < 0.05). There was a trend toward not finding neurovascular conflict at the time of surgery more frequently in the M-MVD than in the E-MVD group (11% vs 7%, p = 0.052). Internal neurolysis was more often performed in the E-MVD group (26% vs 7%, p = 0.001). The 2 groups did not significantly differ in the length of the MVD procedure (approximately 2 hours). Self-reported headaches at 1 month postoperatively were present in 21% of the patients in the M-MVD group versus 7% in the E-MVD group (p = 0.01). Pain outcomes at the most recent followup were equivalent, with patients reporting a 5- to 6-point (70%–80%) improvement in pain intensity, a 5-point (85%) improvement in pain interference with ADLs, and a 6-point (85%) improvement in interference with facial-specific ADLs. Actuarial freedom from pain recurrence was equivalent in the 2 groups, with 80% pain control at 3 years.

CONCLUSIONS

Both the fully endoscopic MVD and the conventional M-MVD appear to provide patients with equivalent pain outcomes. Complication rates were also similar between the groups, with the exception of the rate of headaches, which was significantly lower in the E-MVD group 1 month postoperatively.

Diagnosis and management for trigeminal neuralgia caused solely by venous compression

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

Trigeminal neuralgia - diagnosis and treatment

Introduction Trigeminal neuralgia (TN) is characterized by touch-evoked unilateral brief shock-like paroxysmal pain in one or more divisions of the trigeminal nerve. In addition to the paroxysmal pain, some patients also have continuous pain. TN is divided into classical TN (CTN) and secondary TN (STN). Etiology and pathophysiology Demyelination of primary sensory trigeminal afferents in the root entry zone is the predominant pathophysiological mechanism. Most likely, demyelination paves the way for generation of ectopic impulses and ephaptic crosstalk. In a significant proportion of the patients, the demyelination is caused by a neurovascular conflict with morphological changes such as compression of the trigeminal root. However, there are also other unknown etiological factors, as only half of the CTN patients have morphological changes. STN is caused by multiple sclerosis or a space-occupying lesion affecting the trigeminal nerve. Differential diagnosis and treatment Important differential diagnoses include trigeminal autonomic cephalalgias, posttraumatic or postherpetic pain and other facial pains. First line treatment is prophylactic medication with sodium channel blockers, and second line treatment is neurosurgical intervention. Future perspectives Future studies should focus on genetics, unexplored etiological factors, sensory function, the neurosurgical outcome and complications, combination and neuromodulation treatment as well as development of new drugs with better tolerability.

A retrospective study of neurocombing for the treatment of trigeminal neuralgia without neurovascular compression

BACKGROUND

Microvascular decompression (MVD) is the most effective and non-ablative treatment for trigeminal neuralgia (TN). However, it is not possible when neurovascular compression (NVC) is absent. Neurocombing is a possible treatment option for TN patients without NVC.

AIM

To evaluate and describe the clinical outcome of neurocombing for the treatment of TN when NVC was absent.

METHODS

We retrospectively reviewed the clinical data of the 37 patients of Type 1 TN without NVC who underwent neurocombing in our department between January 2013 and November 2014. The Barrow Neurological Institute (BNI) Pain Intensity scale, the numerical rating scale (NRS) and the quality of life scale (QOL) were evaluated in four stages-presurgical, immediate, at 1 and at 3 years. Pain recurrence was statistically evaluated with Kaplan-Meier analysis.

RESULTS

All the 37 enrolled patients were proved to have no NVC by imaging or exploration in surgery. The mean follow-up duration was 29.50 months. After the procedure, 35 patients (94.6%) experienced immediate pain relief (BNI I) and 2 patients (5.4%) had occasional pain without any medication (BNI II). At 1 year and 3 years, the rates of successful pain relief (BNI I&II) were 86.5 and 83.3%, respectively. 34 patients (91.9%) suffered from mild facial numbness, while it did not exert a harmful impact on their quality of life.

CONCLUSIONS

This study demonstrated that neurocombing is an attractive, effective, safe and durable treatment option for TN when NVC is absent. Further study is needed to explain the complicated and exact mechanism of pain relief by neurocombing.

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.

Is There a Magnetic Resonance Imaging-Discernible Cause for Trigeminal Neuralgia? A Structured Review

BACKGROUND

Trigeminal neuralgia (TN) is a chronic brain condition involving the trigeminal nerve and characterized by severe and recurrent facial pain. Although the cause of TN has been researched extensively, there is a lack of convergence on the physiologic processes leading to pain symptoms. This review seeks to better elucidate the underlying pathophysiology of TN by analyzing the outcomes of studies that use magnetic resonance structural imaging and diffusion-weighted imaging to examine nerve damage in patients with TN.

METHODS

Performing a structured review of the literature, the authors included human magnetic resonance anatomic and diffusion-weighted imaging studies aimed at visualizing the trigeminal nerve or measuring neural damage pertaining to TN. Studies that measured and compared nerve damage in the affected and unaffected sides in patients or patients and controls were analyzed for neural changes associated with TN.

RESULTS

Twenty-five studies met inclusion criteria. Overall, the data from the anatomic and diffusion studies showed decreased volume and cross-sectional area, decreased fractional anisotropy, and increased apparent diffusion coefficient and diffusivity associated with the affected side of patients compared with the unaffected side as well as in patients compared with controls.

CONCLUSIONS

A review of the studies included indicates that neural differences exist between the affected and unaffected sides in patients as well as between patients and controls in both structural and diffusion metrics. The amalgamated data suggest that damage of the trigeminal nerve tissue is commonly found in patients with TN and could be a primary factor in TN pathophysiology.