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

Background

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

Methods

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

Results

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

Conclusions

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

Surgical technique for trigeminal microvascular decompression

Background  

Microvascular decompression (MVD) is a non-ablative technique designed to resolve the neurovascular conflict responsible for typical idiopathic trigeminal neuralgia (TN).     

Preoperative demonstration of the neurovascular compression characteristics with special emphasis on the degree of compression, using high-resolution magnetic resonance imaging: a prospective study, with comparison to surgical findings, in 100 consecutive patients who underwent microvascular decompression for trigeminal neuralgia

Purpose  

Surgical outcome after microvascular decompression (MVD) for primary trigeminal neuralgia (TN) has been demonstrated as being related to the characteristics of the neurovascular compression (NVC), especially to the degree of compression exerted on the root. Therefore, preoperative determination of the NVC features could be of great value to the neurosurgeon, for evaluation of conflicting nature, exact localization, direction and degree of compression. This study deals with the predictive value of MRI in detecting and assessing features of vascular compression in 100 consecutive patients who underwent MVD for TN.     

Patients with idiopathic trigeminal neuralgia have a sharper-than-normal trigeminal-pontine angle and trigeminal nerve atrophy

Background  

Trigeminal neuralgia (TN) is primarily diagnosed by symptoms and patient history. Magnetic resonance (MR) imaging can be helpful in visualizing the neurovascular compression of the trigeminal nerve in TN patients, but the current parameters used as diagnostic markers for TN are less than optimal. The aim of this study is to assess whether the angle between the trigeminal nerve and the pons (the trigeminal-pontine angle) on the affected side of patients with idiopathic TN differs from that of the unaffected side and that found in controls without TN.     

Cardiovascular response during trigeminal ganglion compression for trigeminal neuralgia according to the use of local anesthetics

Objectives  

There are controversies about the use of local anesthetics during balloon compression for trigeminal neuralgia (TN) as a protective factor for cardiovascular events. The objective of this study was to investigate cardiovascular parameters (blood pressure and heart rate [HR]) of patients that underwent trigeminal balloon compression with local anesthetics compared to a control group (placebo).     

Microvascular decompression on patients with trigeminal neuralgia caused by ectatic vertebrobasilar artery complex: technique notes

Background  

Due to its anatomical features, the vertebrobasilar artery complex (VBA) seldom contributes to the neurovascular conflict in patient with trigeminal neuralgia (TN). However, once it offends the trigeminal root, this large artery is really difficult to manipulate during microvascular decompression (MVD) surgery. Therefore, the surgical strategy for such cases needs to be detailed in order to obtain a satisfactory outcome.     

Harvey Cushing’s case series of trigeminal neuralgia at the Johns Hopkins Hospital: a surgeon’s quest to advance the treatment of the ‘suicide disease’

Background  

A review of Dr. Harvey Cushing’s surgical cases at the Johns Hopkins Hospital provided insight into his early work on trigeminal neuralgia (TN). There was perhaps no other affliction that captured his attention in the way that TN did, and he built a remarkable legacy of successful treatment. At the time, surgical interventions carried an operative mortality of 20%.     

Surgical treatment of trigeminal neuralgia. Results from the use of glycerol injection, microvascular decompression, and rhizotomia

Purpose  

The study aims to assess the efficacy and safety of surgical treatment of trigeminal neuralgia (TN) in our department and to identify prognostic factors.     

The role of the cerebellopontine angle cistern area and trigeminal nerve length in the pathogenesis of trigeminal neuralgia: a prospective case-control study

Background

The aim of this prospective study was to evaluate whether the cerebellopontine angle (CPA) cistern area and trigeminal nerve cisternal length play a role in the pathogenesis of trigeminal neuralgia (TN).

Methods

High-resolution 1.5 T magnetic resonance imaging of the posterior fossa was performed in 26 patients with TN and 18 age-matched healthy controls. Axial T2-weighted, three-dimensional constructive interference in steady-state (3D-CISS) was used to measure bilaterally the cross-sectional area of the CPA cistern and trigeminal nerve cisternal length.

Results

In patients, the cross-sectional area of the CPA cistern and trigeminal nerve cisternal length was smaller on the affected side (p?=?0.04). Healthy controls tended to have larger cisternal areas and longer trigeminal nerve lengths than patients (p?=?0.059, p?=?0.071, respectively). Larger CPA cisternal areas tended to be seen in older patients. There was a strong correlation between the cross-sectional area of the CPA cistern and the length of the trigeminal nerve (p?=?0.000).

Conclusions

Smaller CPA cisterns and short cisternal trigeminal nerves impact the pathogenesis of essential TN by facilitating the neurovascular conflict, especially in younger patients. Trigeminal nerve cisternal measurement provides an easy and direct estimation of the CPA area. This information can be used for surgical planning and potentially for outcome prediction.     

Séquences IRM pour la détection des conflits vasculonerveux à l’origine de la névralgie trigéminale et leur valeur prédictive pour la caractérisation du conflit (en particulier le degré de la compression vasculaire)

Background and purpose

A long-term study of the results on trigeminal neuralgia (TN) after microsurgical vascular decompression (Kaplan-Meier curves at 20 years) showed that cure was achieved in 88.1 % of the patients with a neurovascular compression (NVC) producing a large groove on the nerve (Grade III), 78.3 % of the patients with a NVC with nerve distortion or displacement (Grade II), and 58.3 % of the patients with a NVC with simple contact on the nerve (Grade I). Therefore, preoperative visualization of the NVC by MRI and determination of its grading are important for the therapeutic decision. In this study, we investigated the predictive value of MRI for detecting and assessing the degree of vascular compression in trigeminal neuralgia.

Methods

The study included 91 consecutive patients with a preoperative MRI (1.5 Testa) using 3D T2-weighted and angio-MR-TOF. NVC prediction and the degree of compression made by an independent observer were correlated with surgical data.

Results

Eighty of the 91 patients had a NVC on MRI, but 83 (91.2 %) patients showed a NVC at surgical exploration (eight patients had no NCV). Thus, the sensitivity of imaging in detecting a NVC on the symptomatic nerves was 96 % (80/83) and the specificity 100 % (8/8). In addition, imaging analysis predicted the responsible vessel in 88.7 % (71/80) of the cases and characterized the degree of NVC in 85 % (68/80). The Kappa-coefficient (KC) for prediction of the NVC degree was 0.795 for arterial and venous compressions together (p < 0.01; 95 % confidence interval, 0.71-0.88). The CK was 0.758 (p < 0.01, good agreement) for grade I, 0.787 (p < 0.01, good agreement) for grade II and 0.824 (p < 0.01, excellent agreement) for grade III.

Conclusions

High-resolution 3D T2-weighted imaging in combination with angio-MR-TOF is a reliable technique for detecting NVC and predicting the degree of the compression in NVC.     

Percutaneous balloon compression for the treatment of trigeminal neuralgia in patients with multiple sclerosis. Analysis of the potentially prognostic factors

Background  

The role of different procedures for the treatment of drug-resistant trigeminal neuralgia (TN) in patients affected by multiple sclerosis (MS) is under discussion and there are no clear indications in the literature. In particular, the role of percutaneous balloon compression (PBC) has been poorly addressed so far. Moreover, to the best of our knowledge, there are no reports analysing the factors potentially related to the prognosis in these patients. We examined the role of PBC for the treatment of TN in MS patients and investigated the role of some clinical and procedure-related factors in determining the prognosis of these patients.     

Typical trigeminal neuralgia associated with brainstem white matter lesions on MRI in patients without criteria of multiple sclerosis

Introduction  Although compression of the trigeminal nerve by a vascular loop is thought to be the most common cause of trigeminal neuralgia (TN), other aetiologies, such as multiple sclerosis or brainstem infarction may be associated with this disorder. MRI may detect lesions different from vascular loop compression of the trigeminal nerve that may be related to TN. Patients and methods  The pre-operative MRIs of 68 patients without the diagnosis of multiple sclerosis who were operated for typical TN between 1998 and 2003 were retrospectively reviewed Four of these showed hyperintense lesions in the pons on T2 MRI sequences. No patient had prior surgery. These four patients underwent different operations for the control of pain but in two of them only ablative procedures were effective Discussion  Although it is uncertain whether the occurrence of TN in our patients may be attributed to the brainstem abnormalities seen on MRI, the presence of these lesions appears to be the most convincing explanation for the occurrence of pain. We believe that, in the presence of such imaging changes, a destructive procedure should be regarded as the elective surgical treatment in patients presenting with typical TN with or without apparent vascular loop compression of the trigeminal root.     

Preoperative MRI/MRA for microvascular decompression in trigeminal neuralgia: consecutive series of 67 patients

Background  

Microvascular decompression is an accepted treatment for primary trigeminal neuralgia. In recent years, efforts have been made to investigate the role of preoperative MRI/MRA in selecting patients with neurovascular compression.     

The MRI volumetry of the posterior fossa and its substructures in trigeminal neuralgia: a validated study

Purpose  Our aim was to determine whether the anatomical configuration of the posterior fossa and its substructures might represent a predisposition factor for the occurrence of clinical neurovascular conflict in trigeminal neuralgia (TN). Methods  We used MRI volumetry in 18 patients with TN and 15 controls. The volume of the pontomesencephalic cistern, Meckel’s cave and the trigeminal nerve on the clinical and non-affected sides was compared. The reliability has been assessed in all measurements. Results  The posterior fossa volume was not different in the clinical and control groups; there was no difference between the affected and non-affected sides when measuring the pontomesencephalic cistern and Meckel’s cave volume either. The volume of the clinically affected trigeminal nerve was significantly reduced, but with a higher error of measurement. Conclusions  We did not find any association between the clinical neurovascular conflict (NVC) and the size of the posterior fossa and its substructures. MRI volumetry may show the atrophy of the affected trigeminal nerve in clinical NVC.     

Long-term results of microvascular decompression for trigeminal neuralgia and hemifacial spasms according to preoperative symptomatology

Background

Microvascular decompression (MVD) is currently used in several centres for the treatment of trigeminal neuralgia (TN) and hemifacial spasms (HFS). How long-term results relate to the preoperative symptoms still needs to be documented. The primary aim of this study was to assess long-term results of MVD for TN and HFS, as related to the types of preoperative symptoms.

Methods

We performed a retrospective study including all first-time MVDs for TN and HFS done during the 11-year period (1999–2009) in the Department of Neurosurgery, The National Hospital (Rikshospitalet), Oslo. The patients were categorized depending on the pre-operative symptomatology.

Results

The study population includes 303 first-time procedures performed by the senior author (PKE), 243 TN patients (65 % TN without constant pain and 35 % TN with constant pain) and 60 HFS patients (95 % typical HFS and 5 % atypical HFS). The patients were followed for a mean 71 months (range, 14–147). In both the TN and HFS patients, MVD caused lasting symptom relief in a high proportion of patients, including patients with atypical symptoms.

Conclusion

After MVD for TN and HFS, regardless of preoperative symptoms, lasting relief is observed in a high proportion of patients, with a favorable complication profile.     

Intraoperative 3D fluoroscopy in stereotactic surgery

Background  

Intraoperative localisation of a stereotactic probe remains challenging. Stereotactic X-ray, the “gold standard”, as well as intraoperative magnetic resonance (MRI) and computed tomography (CT), require a dedicated operating room (OR). Fluoroscopy with crosshairs confirms only grossly the target position. An alternative would be a mobile three-dimensional (3D) fluoroscopy C-arm. To our knowledge, this is the first report on 3D C-arm fluoroscopy to verify stereotactical trajectories. The objective was to assess the feasibility of using a 3D C-arm to verify the intraoperative trajectory and target.     

Management of bilateral trigeminal neuralgia with trigeminal radiofrequency rhizotomy: a treatment strategy for the life-long disease

Background  

The objective of this study was to evaluate the effectiveness of percutaneous controlled radiofrequency trigeminal rhizotomy (RF-TR) in patients with bilateral trigeminal neuralgia (BTN). Patients were analyzed after RF-TR in terms of outcome, safety and complications.     

Transcranial segment of the trigeminal nerve: macro-/microscopic anatomical study using sheet plastination

Background

Trigeminal neuralgia (TN) may be caused by the mechanical compression of the trigeminal nerve. In the studies on the location of mechanical irritation and entrapment of the nerve, attention has been paid mostly to vascular structures in the subarachnoid space. Few studies have explored the relationship between the trigeminal nerve and its surrounding structures along its course in the skull base. The aim of this study was to examine and trace the root, ganglion and three divisions of the trigeminal nerve and their relationships with surrounding soft and bony structures in the skull base, and to identify the likely mechanical compression points.

Methods

A total of 26 adult cadavers (ten females, 16 males; age range, 45–81 years) were examined in this study, eight for dissection and 16 for sheet plastination study.

Results

Anatomical structures that may make the trigeminal nerve susceptible to entrapment in the skull base were located at (1) the inferolateral edge of the mouth of Meckel’s cave, (2) the middle cranial fossa dura and the lateral wall of the anterior intracavernous portion of the internal carotid artery, (3) the ridge of the medial wall of the foramen rotundum, and (4) the twisted periosteum and venous plexus of the foramen ovale.

Conclusion

This study identified four likely mechanical compression points along the course of the trigeminal nerve in the skull base. Knowledge of these TN-susceptible sites may be useful to both skull base surgeon and TN-animal model researcher, particularly when they study TN without vascular compression.     

Cyberknife radiosurgery for trigeminal neuralgia

BACKGROUND: We present preliminary results using Cyberknife radiosurgery as a noninvasive treatment for trigeminal neuralgia (TN). METHODS: Ten patients with medically refractory TN who were deemed unsuitable for conventional surgery underwent Cyberknife radiosurgery using CT cisternography for localization. RESULTS: Pain relief was achieved in 7 patients, in 5 of them within 24-72 h after irradiation. CONCLUSION: Cyberknife radiosurgery can achieve early-onset pain relief in a subset of TN patients. Improvements using this technique include the absence of a stereotactic ring, potentially improved targeting accuracy produced by CT cisternography and improved dose homogeneity.     

Validation and evaluation of the volumetric measurement of cerebellopontine angle cistern as a prognostic factor of microvascular decompression for primary trigeminal neuralgia

Background

The aim of this study was to analyze the prognostic factors of trigeminal neuralgia (TN) after microvascular decompression (MVD), and to evaluate the volumetric parameters of the cerebellopontine angle (CPA) cistern as a pathogenic factor and imaging predictor.

Methods

This retrospective study included 70 patients with primary TN treated with pure MVD, followed up for at least 1 year and evaluated by high-resolution MR imaging. The volume of the CPA cistern was calculated bilaterally, and the “Cistern Deviation Index” was defined to represent degree of deviation of the CPA cistern. Clinical data and volumetric parameters were compared between patients with TN and age- and sex-matched controls without TN, and between the recurrent and non-recurrent patients.

Results

The transposition procedure had a better outcome than the interposition procedure (P?<?0.001). There was a significant difference in the volume of CPA cistern between the affected and unaffected side (152.1?±?50.1 vs. 179.9?±?63.7 mm³, P?<?0.001) in patients with TN, while no significant difference between the right and left side (158.7?±?44.6 vs. 163.1?±?49.8 mm³, P?=?0.162) in controls. The Cistern Deviation Index was significantly larger in controls than in patients with TN (P?=?0.048), and in the non-recurrent patients than in recurrent patients (P?=?0.040).

Conclusion

We demonstrated that the volumetric parameters of the CPA cistern are a marker for understanding the pathogenesis of TN and useful for predicting the recurrence after MVD. The Cistern Deviation Index might contribute to deciding the surgical approach.