MRI of the Trigeminal Nerve in Patients With Trigeminal Neuralgia Secondary to Vascular Compression. AJR Am J Roentgenol. 2016;206:595-600. [PMID: 26901017 DOI: 10.2214/ajr.14.14156]

The Long-Term Outcomes and Predictors of Microvascular Decompression with or without Partial Sensory Rhizotomy for Trigeminal Neuralgia

Purpose

Microvascular decompression (MVD) and MVD combined with partial sensory rhizotomy (PSR) are effective surgical treatments for idiopathic trigeminal neuralgia (TN). The aim of this study was to compare the long-term outcomes of both MVD and MVD+PSR for the treatment of TN and to identify the factors that may influence the long-term outcomes after MVD or MVD+PSR.

Patients and Methods

From March 2009 to December 2017, 99 patients with idiopathic TN who underwent MVD or MVD+PSR in our hospital (40 MVD, 59 MVD+PSR) were included in the study. The indications for MVD+PSR were as follows: vessels only contacted the nerve root, absence of arterial conflict, or failing to completely decompress from the arteries or veins. All patients were treated by one neurosurgeon and were followed up for at least 1 year. The outcomes were assessed with the Barrow Neurological Institute (BNI) Pain Intensity Scale.

Results

The average follow-up duration was 63.0 months (range, 13.2-118.8 months). Patients in the MVD group were younger than those in the MVD+PSR group (55.1 years and 60.5 years, respectively, P=0.012). A total of 62.5% of the patients in the MVD group and 69.5% of the patients in the MVD+PSR group had favorable long-term outcomes. The Kaplan-Meier survival analysis showed no significant difference in long-term outcomes between the two groups (P=0.202). No factors were associated with long-term outcomes after MVD. For MVD+PSR, a long duration of the disease (odds ratio (OR) 6.967, P=0.016) was associated with unfavorable long-term outcomes, whereas pure arterial compression (OR 0.131, P=0.013) was associated with favorable long-term outcomes.

Conclusion

For patients who are not suitable to undergo pure MVD, MVD+PSR can be used as an effective alternative. For MVD+PSR, patients with a long duration of symptoms may have poor long-term outcomes, while patients with pure arterial compression may have favorable long-term outcomes.

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.

Recent advances in MRI of the head and neck, skull base and cranial nerves: new and evolving sequences, analyses and clinical applications

MRI is an invaluable diagnostic tool in the investigation and management of patients with pathology of the head and neck. However, numerous technical challenges exist, owing to a combination of fine anatomical detail, complex geometry (that is subject to frequent motion) and susceptibility effects from both endogenous structures and exogenous implants. Over recent years, there have been rapid developments in several aspects of head and neck imaging including higher resolution, isotropic 3D sequences, diffusion-weighted and diffusion-tensor imaging as well as permeability and perfusion imaging. These have led to improvements in anatomic, dynamic and functional imaging. Further developments using contrast-enhanced 3D FLAIR for the delineation of endolymphatic structures and black bone imaging for osseous structures are opening new diagnostic avenues. Furthermore, technical advances in compressed sensing and metal artefact reduction have the capacity to improve imaging speed and quality, respectively. This review explores novel and evolving MRI sequences that can be employed to evaluate diseases of the head and neck, including the skull base.

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 >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 >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 < .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 Neuralgia: Medical Management and Surgical Options

Questions from patients about pain conditions and analgesic pharmacotherapy and responses from authors are presented to help educate patients and make them more effective self-advocates. In response to a question about trigeminal neuralgia, its diagnosis, medical therapies, surgical procedures, and treatment outcomes will be discussed.

MRI Findings and Outcomes in Patients Undergoing Microvascular Decompression for Glossopharyngeal Neuralgia

BACKGROUND AND PURPOSE

Glossopharyngeal neuralgia causes extreme paroxysmal pain in the posterior pharynx, tonsillar region, base of tongue, or deep ear, that is, the distribution of the glossopharyngeal nerve. Some cases of glossopharyngeal neuralgia are associated with neurovascular conflict, usually by the posterior inferior cerebellar artery. Such symptomatic compression occurs only in proximal, centrally myelinated portions of the glossopharyngeal nerve near the brainstem. Microvascular decompression provides effective and durable pain relief for properly selected patients with medically refractory glossopharyngeal neuralgia. The purpose of this study is to describe a tailored MRI evaluation of neurovascular conflict in glossopharyngeal neuralgia to improve candidate selection for microvascular decompression.

METHODS

Our team developed a glossopharyngeal neuralgia imaging and evaluation protocol including a grading system for neurovascular conflict of the glossopharyngeal nerve and applied it to evaluate candidates for microvascular decompression.

RESULTS

Our team grades neurovascular conflict as "contact" (vessel touching nerve without intervening cerebrospinal fluid) versus "deformation" (deviation or distortion of nerve from its normal course by the offending vessel). MRIs of patients with glossopharyngeal neuralgia demonstrate proximal neurovascular conflict. Postoperative MRI demonstrates separation of the glossopharyngeal nerve from the offending vessel.

CONCLUSION

A tailored glossopharyngeal neuralgia imaging evaluation protocol is presented. We believe this approach has helped improve microvascular decompression outcomes and reduce unnecessary procedures at our institution. Further research may elucidate whether clinical and imaging features, including neurovascular conflict severity, predict surgical outcome for glossopharyngeal neuralgia.

Neuroimaging of Meckel's cave in normal and disease conditions

Abstract

Meckel’s cave is a dural recess in the posteromedial portion of the middle cranial fossa that acts as a conduit for the trigeminal nerve between the prepontine cistern and the cavernous sinus, and houses the Gasserian ganglion and proximal rootlets of the trigeminal nerve. It serves as a major pathway in perineural spread of pathologies such as head and neck neoplasms, automatically upstaging tumours, and is a key structure to assess in cases of trigeminal neuralgia. The purpose of this pictorial review is threefold: (1) to review the normal anatomy of Meckel’s cave; (2) to describe imaging findings that identify disease involving Meckel’s cave; (3) to present case examples of trigeminal and non-trigeminal processes affecting Meckel’s cave.

Teaching points

• Meckel’s cave contains the trigeminal nerve between prepontine cistern and cavernous sinus.

• Assessment is essential for perineural spread of disease and trigeminal neuralgia.

• Key imaging: neural enhancement, enlargement, perineural fat/CSF effacement, skull base foraminal changes.

After microvascular decompression to treat trigeminal neuralgia, both immediate pain relief and recurrence rates are higher in patients with arterial compression than with venous compression

We explored differences in postoperative pain relief achieved through decompression of the trigeminal nerve compressed by arteries and veins. Clinical characteristics, intraoperative findings, and postoperative curative effects were analyzed in 72 patients with trigeminal neuralgia who were treated by microvascular decompression. The patients were divided into arterial and venous compression groups based on intraoperative findings. Surgical curative effects included immediate relief, delayed relief, obvious reduction, and invalid result. Among the 40 patients in the arterial compression group, 32 had immediate pain relief of pain (80.0%), 5 cases had delayed relief (12.5%), and 3 cases had an obvious reduction (7.5%). In the venous compression group, 12 patients had immediate relief of pain (37.5%), 13 cases had delayed relief (40.6%), and 7 cases had an obvious reduction (21.9%). During 2-year follow-up period, 6 patients in the arterial compression group experienced recurrence of trigeminal neuralgia, but there were no recurrences in the venous compression group. Simple artery compression was followed by early relief of trigeminal neuralgia more often than simple venous compression. However, the trigeminal neuralgia recurrence rate was higher in the artery compression group than in the venous compression group.

Imaging evaluation of trigeminal neuralgia

Trigeminal neuralgia is a debilitating pain syndrome in the sensory distribution of the trigeminal nerve. Compression of the cisternal segment of the trigeminal nerve by a vessel, usually an artery, is considered the most common cause of trigeminal neuralgia. A number of additional lesions may affect the trigeminal nerve anywhere along its course from the trigeminal nuclei to the most peripheral branches to cause facial pain. Relevant differential considerations are reviewed starting proximally at the level of the brainstem.

Percutaneous radiofrequency thermocoagulation for trigeminal neuralgia using neuronavigation-guided puncture from a mandibular angle

Percutaneous radiofrequency thermocoagulation (RFT) of the Gasserian ganglion is an effective treatment for primary trigeminal neuralgia (pTN). Currently Hartel anterior approach is the most commonly used method to access the Gasserian ganglion. However, this approach is associated with high recurrence rate and technical difficulties in certain patients with foramen ovale (FO) anatomical variations. In the present study, we assessed the feasibility of accessing the Gasserian ganglion through the FO from a mandibular angle under computed tomography (CT) and neuronavigation guidance.A total of 108 patients with TN were randomly divided into 2 groups (Group G and Group H) using a random number table. In Group H, Hartel anterior approach was used to puncture the FO; whereas in Group G, a percutaneous puncture through a mandibular angle was used to reach the FO. In both groups, procedures were guided by CT imaging and neuronavigation. The success rates, therapeutic effects, complications, and recurrence rates of the 2 groups were compared.The puncture success rates in Group H and Group G were 52/54 (96.30%) and 49/54 (90.74%), respectively (P = 0.24). The 2 procedural failures in Group H were rescued by using submandibular trajectory, and the 5 failures in Group G were successfully reapproached by Hartel method. Therapeutic effects as measured by Barrow Neurological Institute (BNI) pain scale (P = 0.03) and quality of life (QOL) scores (P = 0.04) were significantly better in Group G than those in Group H at 36 months posttreatment. Hematoma developed in 1/54 (1.85%) cases in Group H, and no cases of hematoma were observed in Group G (P = 0.33). In Group H, RFT resulted in injury to the unintended trigeminal nerve branches and motor fibers in 27/52 (51.92%) cases; in Group G, it resulted in the same type of injury in 7/49 cases (14.29%) (P < 0.01). In Group H, the 24- and 36-month recurrence rates were 12/51 (23.53%) and 20/51 (39.22%), respectively; in Group G, these recurrence rates were 7/49 (12.24%) and 9/49 (16.33%, P = 0.03), respectively.CT- and neuronavigation-guided puncture from a mandibular angle through the FO into the Gasserian ganglion can be safely and effectively used to deliver RFT for the treatment of pTN. This method may represent a viable option to treat TN in addition to Hartel approach.