Demonstration of neurovascular compression in trigeminal neuralgia with magnetic resonance imaging. Comparison with surgical findings in 52 consecutive operative cases

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.

METHODS

The study included 100 consecutive patients with primary TN who were submitted to a preoperative 3D MRI 1.5 T with T2 high-resolution, TOF-MRA, and T1-Gadolinium. Image analysis was performed by an independent observer blinded to the operative findings and compared with surgical data.

FINDINGS

In 88 cases, image analysis showed NVC features that coincided with surgical findings. There were no false-positive results. Among 12 patients that did not show NVC at image analysis, nine did not have NVC at intraoperative observation, resulting in three false-negative cases. MRI sensitivity was 96.7% (88/91) and specificity 100% (9/9). Image analysis correctly identified compressible vessel in 80 of the 91 cases and degree of compression in 77 of the 91 cases. Kappa-coefficient predicting degree of root compression was 0.746, 0.767, and 0.86, respectively, for Grades I (simple contact), II (distortion), and III (marked indentation; p < 0.01).

CONCLUSION

3D T2 high-resolution in combination with 3D TOF-MRA and 3D T1-Gadolinium proved to be reliable in detecting NVC and in predicting the degree of the root compression.

Cranial neuralgias

After a description of the anatomical-functional organization of the human trigeminal system, this chapter discusses the diagnostic and therapeutic options for trigeminal neuralgia (TN). In about 15% of patients who present with the clinical picture of typical TN, this is secondary to a major neurological disease, i.e., benign tumors of the cerebellopontine angle or multiple sclerosis. Some clinical criteria that were used to distinguish between classic and symptomatic TN, such as age at onset, involvement of the ophthalmic division, and responsiveness to medical treatment, are no longer considered reliable. It is recommended that all patients undergo magnetic resonance imaging (MRI) or trigeminal reflex recording. Carbamazepine (CBZ) and oxcarbazepine (OXC) are the first-choice medical treatments. Although other drugs may be effective, these are indicated when the patient cannot reach the therapeutic dosage of CBZ/OXC because of adverse events. Patients unresponsive to CBZ/OXC should be made aware of the available surgical interventions. Surgical procedures (including percutaneous lesions to the ganglion/root, microvascular decompression (MVD) in the posterior fossa, and gamma knife radiosurgery) are extremely efficacious with relatively few complications: each procedure has some advantage and disadvantage with respect to the other. Only MVD is a non-destructive procedure. This chapter also describes management of glossopharyngeal neuralgia, which is often misdiagnosed, and some other chronic pain conditions mediated by the trigeminal system, such as ophthalmic postherpetic neuralgia (PHN).

Vascular compression of the trigeminal nerve is a frequent finding in asymptomatic individuals: 3-T MR imaging of 200 trigeminal nerves using 3D CISS sequences

BACKGROUND

The aim of this study was to assess whether individuals without symptoms of trigeminal neuralgia exhibit vascular compression of the trigeminal nerve. This was investigated using ultra-high-field MR imaging.

METHODS

One hundred subjects were imaged using a 3-T magnet and high-spatial-resolution three-dimensional (3D) MR imaging with 3D constructive interference in steady-state sequences.

FINDINGS

Neurovascular compression (NVC) was detected in 92 of the individuals, with 83 cases bilateral and 9 unilateral. In total, 175 (87.5%) of the 200 nerves examined showed NVC. In 58% of the affected individuals, the vessel was compressing a site in the proximal third of the trigeminal nerve. Eighty-six percent of the compressing vessels were arteries, and 14% were veins.

CONCLUSIONS

Ours is the first study to have evaluated NVC of the trigeminal nerve in asymptomatic individuals using 3-T MR imaging. The high prevalence of compression we observed is close to rates of NVC that have been documented in large series of microvascular decompression for trigeminal neuralgia. Our findings strongly suggest that vascular compression of the trigeminal nerve is not necessarily pathological.

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

Object

Neurovascular compression (NVC) of the trigeminal nerve is associated with trigeminal neuralgia (TN), but also occurs in many patients without facial pain. This study is designed to identify anatomical characteristics of NVC associated with TN.

Methods

Thirty patients with Type 1 TN (intermittent shocklike pain) and 15 patients without facial pain underwent imaging for analysis of 30 trigeminal nerves ipsilateral to TN symptoms, 30 contralateral to TN symptoms, and 30 in asymptomatic patients. Patients underwent 3-T MR imaging including balanced fast-field echo and MR angiography. Images were fused and reconstructed into virtual cisternoscopy images that were evaluated to determine the presence and degree of NVC. Reconstructed coronal images were used to measure nerve diameter and crosssectional area.

Results

The incidence of arterial NVC in asymptomatic nerves, nerves contralateral to TN symptoms, and nerves ipsilateral to TN symptoms was 17%, 43%, and 57%, respectively. The difference between symptomatic and asymptomatic nerves was significant regarding the presence of NVC, nerve distortion, and the site of compression (p < 0.001, Fisher exact test). The most significant predictors of TN were compression of the proximal nerve (odds ratio 10.4) and nerve indentation or displacement (odds ratio 4.3). There was a tendency for the development of increasingly severe nerve compression with more advanced patient age across all groups. Decreased nerve size was observed in patients with TN but did not correlate with the presence or extent of NVC.

Conclusions

Trigeminal NVC occurs in asymptomatic patients but is more severe and more proximal in patients with TN. This information may help identify patients who are likely to benefit from microvascular decompression.

Trigeminal neuralgia and pain related to multiple sclerosis

Although many patients with multiple sclerosis (MS) complain of trigeminal neuralgia (TN), its cause and mechanisms are still debatable. In a multicentre controlled study, we collected 130 patients with MS: 50 patients with TN, 30 patients with trigeminal sensory disturbances other than TN (ongoing pain, dysaesthesia, or hypoesthesia), and 50 control patients. All patients underwent pain assessment, trigeminal reflex testing, and dedicated MRI scans. The MRI scans were imported and normalised into a voxel-based, 3D brainstem model that allows spatial statistical analysis. The onset ages of MS and trigeminal symptoms were significantly older in the TN group. The frequency histogram of onset age for the TN group showed that many patients fell in the age range of classic TN. Most patients in TN and non-TN groups had abnormal trigeminal reflexes. In the TN group, 3D brainstem analysis showed an area of strong probability of lesion (P<0.0001) centred on the intrapontine trigeminal primary afferents. In the non-TN group, brainstem lesions were more scattered, with the highest probability for lesions (P<0.001) in a region involving the subnucleus oralis of the spinal trigeminal complex. We conclude that the most likely cause of MS-related TN is a pontine plaque damaging the primary afferents. Nevertheless, in some patients a neurovascular contact may act as a concurring mechanism. The other sensory disturbances, including ongoing pain and dysaesthesia, may arise from damage to the second-order neurons in the spinal trigeminal complex.

Operative treatment of trigeminal neuralgia: review of current techniques

Surgical approaches to pain management are performed when medication cannot control pain or patients cannot tolerate the adverse effects of the medication. Microvascular decompression (MVD) is generally performed when the patient is healthy and relatively young. Partial sensory rhizotomy is performed in addition to, or instead of MVD, in patients in whom significant compression of the trigeminal sensory root does not exist or in whom MVD is technically not feasible. Three percutaneous ablative procedures and gamma knife radiosurgery (GKS) are also performed when MVD cannot be performed. The result of MVD is superior to that of the 3 ablative procedures. GKS is inferior to the 3 ablative procedures in terms of initial pain relief and recurrence, but superior in terms of complications. Peripheral procedures are usually performed in patients not suitable for or not wishing to have other procedures. However, no strict rules exist and each patient should be evaluated individually.

Microvascular decompression for intractable singultus: technical case report

OBJECTIVE

Intractable singultus is a rare but significantly disruptive clinical phenomenon that often accompanies other diseases but can present in isolation due entirely to intracranial pathology. We report a case of intractable singultus that improved after microvascular decompression and present a comprehensive review of singultus by discussing its similarity to other cases of microvascular decompression, its history and etiology, and its evolutionary basis.

CLINICAL PRESENTATION

The patient exhibited intractable singultus for 15 years, resistant to multiple medical regimens.

INTERVENTION

Microvascular decompression to relieve pressure on the tenth cranial nerve and medulla oblongata resulted in near total resolution of the singultus.

CONCLUSION

Neurovascular compression should be considered a potentially reversible cause of intractable singultus, a significantly disabling clinical phenomenon.

Microvascular decompression of cochleovestibular nerve

The role of microvascular decompression (MVD) in the management of trigeminal neuralgia, hemifacial spasms and glossopharyngeal neuralgia is well-established. However, controversy persisted as to the use of MVD in cochleovestibular neurovascular compression syndrome. This report provides a review of all the published studies on MVD of the eighth (8th) nerve in alleviating cochleovestibular symptoms and presents three additional patients who underwent MVD of the eighth nerve for tinnitus or vertigo. Nineteen studies were identified. Five were case reports. The remaining have sample sizes ranging from 4 to 207 patients. Quantitative and qualitative reviews of all studies were performed, focusing on the selection criteria for surgery, efficacy and safety of the procedure. Selection criteria for surgery were variable. No standardised outcome measures were used and all studies rely on patient subjective assessment of surgical outcome. Nonetheless, the results suggest that MVD of the eighth nerve produces good outcome with low morbidity in selected cases.

Anatomical study of the trigeminal and facial cranial nerves with the aid of 3.0-tesla magnetic resonance imaging

Object

Neuroimages often reveal that the trigeminal or facial nerve comes in contact with vessels but does not produce symptoms of trigeminal neuralgia (TN) or hemifacial spasm (HFS). The authors conducted this study to determine how often the trigeminal and facial nerves came in contact with vessels in individuals not suffering from TN or HFS. They also investigated the correlation between aging and the anatomical measurements of the trigeminal and facial nerves.

Methods

Between November 2005 and August 2006, 220 nerves in 110 individuals (60 women and 50 men; mean age 55.1 years, range 19–85 years) who had undergone brain magnetic resonance (MR) imaging for other reasons were studied. The lengths, angles, ratio, and contact points were measured in each individual. A correlation between each parameter and age was statistically analyzed.

Results

The mean (± standard deviation) length of the trigeminal nerve was 9.66 ± 1.71 mm, the mean distance between the bilateral trigeminal nerves was 31.97 ± 1.82 mm, and the mean angle between the trigeminal nerve and the midline was 9.71 ± 5.83°. The trigeminal nerve was significantly longer in older patients. Of 220 trigeminal nerves, 108 (49.0%; 51 women and 57 men) came in contact with vasculature. There was 1 contact point in 99 nerves (45%) and 2 contact points in 9 nerves (4.1%). Contact without deviation of the nerve was seen in 91 individuals (43 women and 48 men), and mild deviation was noted in 17 individuals (8 women and 9 men). There was no moderate or severe deviation in any individual in this series. The mean length of the facial nerve was 29.78 ± 2.31 mm, the mean distance between the bilateral facial nerves was 28.65 ± 2.22 mm, the angle between the nerve and midline was 69.68 ± 5.84°, and the vertical ratio at the porus acusticus was 0.467 ± 0.169. Of all facial nerves, 173 (78.6%; 101 in women and 72 in men) came in contact with some vasculature. Contact without deviation was seen on 64 sides (in 37 women and 27 men), mild deviation on 98 sides (in 57 women and 41 men), and moderate deviation on 11 sides (in 7 women and 4 men). There was no severe deviation of the facial nerve in this series. The proximal length of the facial nerve, interval, angle, and ratio against the age were significantly shorter or smaller in the older individuals.

Conclusions

The findings in asymptomatic individuals in this study will help in deciding which findings observed on MR images may cause symptoms. In addition, the authors describe the variations of normal anatomy in older individuals. Knowledge of the normal anatomy helps to hone the diagnostic practices for microvascular decompression, which may increase the feasible results on such surgery.

Management of neuropathic orofacial pain

Current management of painful trigeminal neuropathies relies on pharmacological (topical and systemic), surgical, and complementary modalities. There is, however, a lack of quality research relating to the effectiveness of these modalities. In this review we analyze the available data that relates to the therapy of trigeminal neuralgia, postherpetic neuralgia, and posttraumatic neuropathies and provide clinical guidelines. The review focuses on medical management, as well as surgical and other interventions for painful neuropathies.

Endoscope-assisted microvascular decompression for trigeminal neuralgia: technical case report

OBJECTIVE

Microvascular decompression may fail to relieve trigeminal neuralgia because a compressing vessel at the root entry zone may be overlooked during surgery. Alternatively, effective decompression may not always be achieved with the visualization provided by the microscope alone. We theorized that the addition of an endoscope would improve the efficacy of microvascular decompression.

METHODS

We retrospectively reviewed microvascular decompression of the trigeminal nerve in 114 patients. Before closure, the endoscope was used to inspect the root entry zone. When visualization with the microscope was poor, the endoscope was used to identify an aberrant vessel and to perform or improve the subsequent decompression.

RESULTS

Of 114 patients who underwent microvascular decompression, 113 successfully underwent endoscopy. In 38 patients (33%), endoscopy revealed arteries that were poorly seen (25%) or not seen at all (8%) with the microscope. At a mean follow-up period of 29 months, the pain was completely relieved in 112 patients (99.1%), all of whom were off medication. Complications included trigeminal dysesthesias in nine patients and a wound infection, partial hearing loss, and complete hearing loss in one patient each. The overall complication rate was 9%.

CONCLUSION

Endoscopy is a simple and safe adjunct to microscopic exploration of the trigeminal nerve. The markedly improved visualization increases the likelihood of identifying the offending vessel and consequently of achieving satisfactory decompression of the nerve. Thus far, the success rate has been high, and the complication profile is comparable to that of other large series.

Quadruple vessel involvement at root entry zone in trigeminal neuralgia

The author describes a rare case of trigeminal neuralgia where four major named vessels of the posterior circulation were detected to be in close approximation to the trigeminal nerve. The quadruple vessel compression included a tortuous dilated basilar trunk, ipsilateral anterior inferior cerebellar artery, a superior cerebellar artery and superior petrosal vein. All vessels were related to the root entry zone of the nerve. Significance of such a multiple vessel neuovascular conflict at the root entry zone is discussed, highlighting technical implications during surgical management and its prognostic relevance.

Persistent trigeminal artery associated with trigeminal neuralgia: hypothesis of neurovascular compression

INTRODUCTION

The aim of this study was to determine the prevalence of persistent trigeminal artery (PTA) associated with trigeminal neuralgia (TN).

METHODS

From January 1998 to January 2004, 288 MRI scans of patients examined for trigeminal deficits were retrospectively evaluated. MRI was performed at 1.5 T. Scan protocols included cerebral TSE T2-weighted imaging, contrast enhanced SE T1-weighted imaging and thin-section 3D T2-weighted imaging of the temporal bones, 3D TOF pre- and postcontrast MR angiography. TN was defined as episodes of intense stabbing, electric shock-like pain in areas of the face supplied by the trigeminal branches. Neurovascular compression (NVC) was assumed to be present if the patient showed clinical features of TN, if there was contact between an artery and the trigeminal nerve on the affected side, and if other pathology had been excluded. The prevalence and confidence intervals were calculated (95% CI of the prevalence was based on the exact binomial distribution).

RESULTS

Of 288 patients, 136 matched the criteria for TN. In this series a PTA was detected in three patients, which in all patients was on the same side as the TN. The prevalence of a PTA in patients presenting with TN was 2.2% (CI 0.005-0.06).

CONCLUSION

Previous studies have shown PTA as an incidental finding in 0.1-0.6% of cerebral angiograms. The prevalence of a PTA in patients with TN was 2.2%. With respect to the clinical significance, a PTA has to be considered in TN and the diagnosis of a PTA can easily be made using MR imaging/angiography.

Volumetric Measurement of the Pontomesencephalic Cistern in Patients with Trigeminal Neuralgia and Healthy Controls

OBJECTIVE:

Most so-called idiopathic trigeminal neuralgias (TN) are caused by neurovascular compression. Does the size of the cerebellopontine cistern play a role in favoring a neurovascular conflict? The aim of this prospective study was to measure the volume of the parapontine cistern in patients with idiopathic TN and to perform a comparison with healthy controls.

METHODS:

In 25 patients with unilateral idiopathic TN and 17 healthy participants, high-resolution 1.5-T magnetic resonance imaging scans of the parapontine region and the trigeminal nerve were performed. A coronal T2-weighted, true fast imaging steady-state precession sequence with a slice thickness of 0.9 mm was used to define the surrounding cerebrospinal fluid space from the trigeminal root entry zone to Meckel's cave. The volume of the pontomesencephalic cistern was calculated using a standardized method.

RESULTS:

The mean difference of the volume of the affected and opposite side was 13% in patients with TN. In all patients, a significantly smaller volume of the cistern was found on the affected side (P &lt; 0.01). Healthy controls showed a mean volumetric side difference of 9%, which was not significant (P &gt; 0.05).

CONCLUSION:

High-resolution magnetic resonance imaging scans are able to demonstrate significant volumetric differences of the pontomesencephalic cistern in patients with unilateral TN. A smaller cistern may be correlated with the occurrence of a neurovascular compression, and these findings support the neurovascular compression theory in idiopathic TN.

Facial pain: clinical differential diagnosis

Differential diagnosis of pain in the face as the presenting complaint can be difficult. We propose an approach based on history and neurological examination, which allows a working diagnosis to be made at the bedside, including aetiological hypotheses, leading to a choice of investigations. Neuralgias are characterised by stabs of short lasting, lancinating pain, and, although neuralgias are often primary, imaging may be needed to exclude symptomatic forms. Facial pain with cranial nerve symptoms and signs is almost exclusively of secondary origin and requires urgent examination. Facial pain with focal autonomic signs is mostly primary and belongs to the group of the idiopathic trigeminal autonomic cephalalgias, but can occasionally be secondary. Pure facial pain is most often due to sinusitis and the chewing apparatus, but also a multitude of other causes. The pain can also be idiopathic. Imaging as well as non-neurological specialist assessment is often necessary in these cases.

Vaskuläre Erkrankungen des Kleinhirnbrückenwinkels

Vascular anomalies of the cerebellopontine angle are rare compared to tumors in this area. Irritation of the trigeminal, facial, or vestibulocochlear nerve may cause trigeminal neuralgia, hemifacial spasm and vertigo, or tinnitus accordingly. Vessel loops in the cerebellopontine cisterns may cause compression at the root entry or exit zone of the cranial nerves V, VII, and VIII, a phenomenon which is called "vascular loop syndrome." Megadolichobasilar artery and aneurysms of the vertebrobasilar system can also lead to dislocation and compression of the cranial nerves and brain stem. Three-dimensional CISS MR imaging and MR angiography are useful in the detection of neurovascular compression. Microvascular decompression is an effective surgical procedure in the management of compression syndromes of the cranial nerves V, VII, and VIII.

Multimodality treatment of trigeminal neuralgia: impact of radiosurgery and high resolution magnetic resonance imaging

This study was conducted to evaluate the two main surgical modalities, microvascular decompression (MVD) and gamma-knife radiosurgery (GK), the treatment of trigeminal neuralgia (TN) and outline for an algorithm for the selection of these procedures. The authors have identified distinct differences in the two treatment groups and formulated a scale that predicts the outcome and satisfaction of patients who underwent the procedures. This series included 34 TN patients treated in 2000 and 2001 with MVD (19) and GK (15). Patients with TN associated with tumor or multiple sclerosis were excluded. Each patient's age, past medical history, clinical features of pain or pre-operative pain grade, duration of TN, medications, and prior surgical procedures were recorded. Long-term results were assessed by a structured interview by telephone. Clinical outcome was classified as excellent (complete relief without medications and numbness), good (complete relief without medications), fair (> 50% relief or with substantial numbness and weakness), or poor (< 50% relief or treatment failure). Patient self-rated satisfaction score was rated on a scale of 1 (unsatisfied) to 10 (completely satisfied). Statistical analysis was performed by paired t-tests and anova with post-hoc analysis by the Tukey-Kramer method. The median follow-up was 17 months (18 months for MVD and 16 months for GK). The average age of MVD patients was 61 years compared to 74 years for GK patients (p = 0.0005). In both groups there was a female majority (68% for MVD and 60% for GK). The latency between first symptom of TN and treatment procedure was 3.0 years for MVD and 3.9 years for GK (p > 0.05). There was no significant difference in pain grade between the two groups. The average TN complexity grade was significantly different between the two groups (3.0 for MVD and 5.8 for GK) (p < 0.001). Average response to procedure for MVD was 3.4 (good) and 2.4 (fair) for GK (p = 0.017). The satisfaction outcome for MVD was 8.7 compared to 6.4 for GK (p = 0.02). There was a significant correlation (r = -0.818, p < 0.001) between TN complexity grade and response. Additionally, a significant correlation between TN complexity grade and patient satisfaction was found (r = -0.763, p < 0.0001). The data here support the treatment algorithm employed by the senior author (JFA) of this study. The TN complexity grade accurately correlates with the patient's response and satisfaction to the surgical procedure. This complexity grade may be useful for patient counseling when choosing between treatment options.

Neurovascular relationship at the trigeminal root entry zone in persistent idiopathic facial pain: findings from MRI 3D visualisation

BACKGROUND

Patients with atypical neuralgia or atypical facial pain have been surgically treated with microvascular decompression (MVD) of the trigeminal root entry zone (TREZ). There are no data regarding the sensitivity and specificity of a vessel-TREZ relationship as a cause of pain in patients with persistent idiopathic facial pain (PIFP) according to the definition given by the International Headache Society (IHS).

METHODS

The TREZ was visualised by 3D CISS MRI in 12 patients with unilateral PIFP according to the IHS criteria.

RESULTS

The frequency of artery-TREZ, vein-TREZ, or vessel (artery/vein)-TREZ contacts on the symptomatic and asymptomatic sides did not differ significantly. On the symptomatic side, vessel-TREZ contact was found in 58% of patients (sensitivity). On the asymptomatic side, vessel-TREZ contact was absent in 33% of patients (specificity).

CONCLUSIONS

On the basis of the low sensitivity and specificity found in the present study, PIFP cannot be attributed to a vessel-TREZ contact, and therefore, pain relief after MVD cannot be expected.

Algies faciales typiques et atypiques : du diagnostic au traitement

PURPOSE

Facial pain is a frequently encountered symptom in general medical practice and encompass a wide group of facial problems. As correct diagnosis can usually be reached by history and physical examination for well defined typical clinical entities (trigeminal neuralgia, cluster headache) atypical facial pain may have many other potential causes (sinuses infection, temporomandibular joint syndrome, dental disorders...) so that diagnosis not appear an easy task.

CURRENT KNOWLEDGE AND KEYPOINTS

Anatomical and physiological organization of facial nociceptive system, particularly trigeminal system, may explain the variability of facial pain. Although symptoms have been clearly identified mechanism of pain production remains controversial. Several factors (psychological, neurological, endocrine...) and mechanisms (neuropathic, vascular, myoarticular) may coexist and explain trouble in diagnosing and treating facial pain.

FUTURE PROSPECTS AND PROJECTS

Better knowledge in identifying the cause of facial pain may lead to improve patient care and avoid patient frustration, medical nomadism, repetitive dental and otolaryngologic procedures, and finally non-compliance with treatment.

Orofacial Pain—Part I

Orofacial pain is a common complaint, affecting the lives of millions of people around the world. Chronic orofacial pain often constitutes a challenging diagnostic problem that can be complicated by psychosocial factors and typically requires multidisciplinary treatment approaches. The fundamental prerequisite for successful management of orofacial pain is an accurate diagnosis. Generating a differential diagnosis, which will ultimately lead to a definite diagnosis, requires thorough knowledge of the diagnostic range of orofacial pain. There is a vast array of orofacial pain categories including: (1) musculoskeletal, (2) neuropathic, (3) vascular, (4) neurovascular, (5) idiopathic, (6) pain caused by local, distant, or systemic pathology, and (7) psychogenic. This article presents the salient clinical features and the therapeutic approaches for the various subtypes of musculoskeletal and neuropathic pain. Musculoskeletal pain is the most prevalent orofacial pain, with temporomandibular disorders and tension-type headache being the main examples. Neuropathic pain develops secondary to neural injury and/or irritation and can be distinguished into episodic, including trigeminal neuralgia and glossopharyngeal neuralgia, as well as continuous, such as herpetic and postherpetic neuralgia, traumatic neuralgia, and Eagle's syndrome.

Trigeminal neuralgia in a patient with multiple sclerosis and chronic inflammatory demyelinating polyneuropathy

BACKGROUND

Trigeminal neuralgia (TN) is characterized by unilateral, severe, brief, stabbing, recurrent pain in the distribution of one or more branches of the fifth cranial nerve. Symptomatic or secondary TN involves TN-like pain that develops owing to a central nervous system lesion (benign or malignant) or to multiple sclerosis (MS).

CASE DESCRIPTION

The authors present a report of a unique case of a 43-year-old patient with unilateral TN, MS and concomitant chronic inflammatory demyelinating polyneuropathy. The facial pain preceded any other manifestations of the systemic disorders, and only after repeated neurological examinations were these diagnoses established.

CLINICAL IMPLICATIONS

Magnetic resonance imaging of the brain and repeated neurological evaluations should be implemented in all patients with TN to rule out the presence of underlying disease. The dental practitioner should be familiar with TN to avoid unnecessary dental interventions and ensure prompt initiation of appropriate treatment.

Optic nerve compression by normal carotid artery in patients with normal tension glaucoma

AIM

To determine whether compression of the optic nerve by the intracranial carotid artery (ICA) can be a causative factor of normal tension glaucoma (NTG).

METHODS

The medical records of 103 eyes of 54 Japanese patients with NTG and 104 eyes of 52 age matched control patients were reviewed. The neuroradiological findings of magnetic resonance images (MRI) were evaluated to determine the relation between the optic nerve and ICA. The clinical characteristics and general medical conditions, such as diabetes and systemic hypertension, were also compared between the two groups.

RESULTS

The prevalence of optic nerve compression by the ICA in patients with NTG was 49.5%, which was significantly higher than that in control group with 34.6% (p = 0.035). Bilateral compression of the optic nerve was detected in 22 patients with NTG (40.7%), and this was also significantly higher (p = 0.029) than that in the control group (11 patients, 21.2%). In the NTG group, eyes with cup/disc ratio (C/D ratio) > or =0.7 showed a higher percentage of compression (52.6%) compared with eyes with C/D ratio of <0.7 (12.5%; p = 0. 042). The presence of diabetes and hypertension did not affect the incidence of optic nerve compression by ICA significantly.

CONCLUSIONS

The significantly higher percentage of NTG patients who had optic nerve compression by the ICA suggests that compression of the optic nerve by ICA may be a possible causative factor or a risk factor for optic nerve damage in some patients with NTG.

Is preoperative high-resolution magnetic resonance imaging accurate in predicting neurovascular compression in patients with trigeminal neuralgia?

High-resolution magnetic resonance imaging (HR-MRI) using three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) and double-dose contrast-enhanced three-dimensional fast spoiled gradient echo (3D-FSPGR) sequences is considered to be a useful tool in detecting neurovascular compression in patients with trigeminal neuralgia. The purpose of this study was to analyze the accuracy and preoperative diagnostic value of these high-resolution imaging techniques in patients with trigeminal neuralgia, in a single-blind study. The preoperative MRI images of 21 consecutive patients were matched to one neuroradiologist, who was blind as to which side exhibited the symptoms. The images and post-processing multiplanar reconstructions were compared with the video-documented operative observations. HR-MRI using only 3D-FSPGR sequences demonstrated neurovascular compression in accordance with the intraoperative finding in 11 patients (52.4%). In the subgroup where, additionally, 3D-FIESTA sequences were available, neurovascular compression was in accordance with the intraoperative finding in 71.4% (n = 7). High-resolution magnetic resonance imaging using double-dose contrast-enhanced 3D-FSPGR and 3D-FIESTA sequences is currently not sufficient enough to make an accurate prediction of neurovascular compression in a single-blind setting. These 3D imaging techniques currently provide only limited information, and one should consider their use carefully when identifying patients with trigeminal neuralgia from operation until image quality is improved by superior image resolution that can accurately discriminate vessels surrounding the trigeminal root entry zone.

Craniofacial Neural Disorders: A Guide for Diagnosis and Management

The purpose of this article is to provide a succinct diagnosis and management regimen for neural disorders of the craniofacial region. This guide is an attempt to organize available data in a format for use by the craniofacial pain practitioner. The management regimens are brief because the management of many of these disorders may be outside the scope of dentistry. Also, the purpose of this guide is to be user-friendly and complete. Terminology is based on a literature review so individual disorders may be researched more completely.

Gamma knife radiosurgery for trigeminal neuralgia: a study of predictors of success, efficacy, safety, and outcome at LSUHSC

BACKGROUND

Trigeminal neuralgia (TN) is a painful condition of controversial origin; however, vascular compression of the root entry zone of the trigeminal nerve is thought to be responsible in some cases. Recently, stereotactic radiosurgery has been established as an alternative treatment for medically intractable TN.

METHODS

Forty patients with medically refractory TN underwent gamma knife surgery for pain control at our institution. Dose planning was based on high-resolution, contrast-enhanced, axial, volume acquisition magnetic resonance images. Images were reviewed to detect vascular compression of the trigeminal nerve at the root entry zone by an observer blinded to the affected side and the outcome. Another observer, blinded to radiologic findings, conducted the patient follow-up. Results were classified as excellent and good (favorable outcomes) and failure (unfavorable) based upon the intensity of pain, frequency of episodes, pain medications, and need for additional interventions after radiosurgery.

RESULTS

Pain was left-sided in 22 patients and right-sided in 18 patients. Vascular compression of the affected nerve at the root entry zone was demonstrable in 14 patients. Prescription dose ranged from 70 to 90 Gy. At a median follow-up of 14 months (range, 3-31 months), 16 patients (40%) had excellent pain control, 12 (30%) had good control, while 12 (30%) had failed treatment. The Kaplan-Meier actuarial pain control rate at 15 months was 82.25 +/- 0.8% (95%CI). Magnetic resonance detectable vascular compression did not affect the outcome (p = 0.6). Increasing marginal dose (> or =40Gy) was a significant predictor of favorable outcome (p = 0.015).

CONCLUSIONS

gamma knife surgery is an effective and safe treatment for TN. In our study, we found that vascular compression of the nerve at the root entry zone was not a predictor of the outcome of gamma surgery for TN. The outcome improves with marginal prescription dose of 80 Gy or higher.

Painful ophthalmologic disorders and eye pain for the neurologist

Neurologists should be aware of the following causes of eye pain: (1)ocular and orbital disorders with or without visible pathology of the eye (eg,redness, corneal opacity, or proptosis); (2) ophthalmologic syndromes associated with headache; and (3) headache syndromes associated with ophthalmologic findings.

Trigeminal neuralgia: evaluation of neuralgic manifestation and site of neurovascular compression with 3D CISS MR imaging and MR angiography

PURPOSE

To evaluate three-dimensional (3D) constructive interference in steady-state (CISS) magnetic resonance (MR) imaging and MR angiography with multiplanar reconstruction (MPR) for detection of neurovascular compression (NVC) in patients with trigeminal neuralgia and to evaluate the relationship between clinical symptoms related to trigeminal branches and those related to the site of trigeminal nerve compression.

MATERIALS AND METHODS

Fifty-four consecutive patients with trigeminal neuralgia were examined at 3D CISS imaging and MR angiography with a 1.5-T MR system. Original transverse and four reformatted images were used for image interpretation. Vascular contact with the trigeminal nerve at the root entry zone (REZ) was determined, and the nature of the involved vessels was identified. The position of the blood vessel compressing the nerve was classified into cranial, caudal, medial, or lateral sites. Statistical analysis was performed with the chi2 test or the Fisher exact test between two groups and with the chi2 test among more than two groups.

RESULTS

In 12 of 15 patients who underwent surgery, the artery that was considered a responsible vessel at 3D CISS imaging and MR angiography was confirmed as such. In the other three patients, the vein was the responsible vessel, which was detected only at 3D CISS imaging. Sixteen (89%) of 18 patients with symptoms related to the maxillary division had NVC at the medial site of the REZ, while 16 (76%) of 21 patients with symptoms related to the mandibular division had NVC at the lateral site (P <.001, chi2 test).

CONCLUSION

3D CISS MR imaging with MPR is useful in the detection of NVC in patients with trigeminal neuralgia, compared with MR angiography. A close relationship was found between the region of neuralgic manifestation and the site of trigeminal nerve compression.

Trigeminal Neuralgia Associated with a Primitive Trigeminal Artery Variant: Case Report

OBJECTIVE AND IMPORTANCE

A variant type of the primitive trigeminal artery (PTA) is a rare anomalous vessel that originates from the internal carotid artery and directly supplies the territory of the anteroinferior cerebellar artery and/or the superior cerebellar artery. We report a case of trigeminal neuralgia associated with this PTA variant, and we discuss the characteristics of this vessel.

CLINICAL PRESENTATION

A 51-year-old woman presented with a 10-year history of left paroxysmal facial pain. Magnetic resonance angiography and cerebral angiography demonstrated that an aberrant vessel originating from the left internal carotid artery directly supplied the cerebellum, without a basilar artery anastomosis.

INTERVENTION

Surgical exploration was performed via a left retrosigmoid approach. A loop of the aberrant vessel, which entered the posterior fossa through the isolated dural foramen, was compressing the trigeminal nerve. This aberrant vessel was displaced medially from the nerve with a prosthesis, with care to avoid kinking and avulsion of the perforating arteries. The patient's neuralgia resolved postoperatively.

CONCLUSION

Although the PTA variant is frequently associated with intracranial aneurysms, it is extremely rare for the variant to lead to trigeminal neuralgia. During microvascular decompression surgery, surgeons should be careful to prevent injury of the perforating arteries arising from the PTA variant.

Demonstration of neurovascular compression in trigeminal neuralgia and hemifacial spasm with magnetic resonance imaging: comparison with surgical findings in 60 consecutive cases

BACKGROUND

Until recently, it has been impossible to demonstrate vascular compression at the root entry or exit zone (REZ) of the trigeminal nerve and facial nerve in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS) preoperatively, although surgical findings have revealed apparent neurovascular compression and its correction has resulted in a good outcome in most cases. Revealing the anatomic correlation between nerves and vessels at the REZ preoperatively would be useful to predict operative findings.

METHODS

To assess whether the vascular contact of the nerve at the REZ could be demonstrated preoperatively, high-resolution magnetic resonance tomographic angiography (MRTA) was performed in 21 patients with TN and 39 with HFS. Neuroradiological findings were compared with the operative findings in all patients. Contralateral asymptomatic nerves were evaluated as a control.

RESULTS

MRTA correctly identified offending vessels in 14 (67%) of the 21 TN and 34 (87%) of the 39 HFS patients. Failure to identify neurovascular contact was noted in the cases with compression by veins or small arteries, thickened arachnoid, or distal compression. Neurovascular contact was also observed in 15% of the asymptomatic nerves. The deformity of the nerve seemed to be a more important factor for determining operative indication.

CONCLUSIONS

MRTA could demonstrate offending vessels in TN and HFS at a high rate and was useful to predict operative findings. MRTA gave supportive evidence of surgical indications in patients with TN and HFS, although attention should be paid to the fact that MRTA did not necessarily detect all of the offending vessels.

Preoperative evaluation of neurovascular compression in patients with trigeminal neuralgia by use of three-dimensional reconstruction from two types of high-resolution magnetic resonance imaging

OBJECTIVE

To assess the value of three-dimensional (3-D) images reconstructed from 3-D constructive interference in steady state (3-D-CISS) and 3-D fast inflow with steady-state precession (3-D-FISP) images for the visualization of neurovascular compression in patients with trigeminal neuralgia.

METHODS

Twenty-four consecutive patients with trigeminal neuralgia underwent preoperative 3-D-FISP and 3-D-CISS imaging. 3-D reconstruction of nerves and vessels was performed with the use of a volume-rendering method. We compared the 3-D reconstructed images with intraoperative findings.

RESULTS

3-D-CISS and 3-D-FISP images scanned from the same position clearly delineated the trigeminal nerve and vessels. 3-D reconstructed images showed the spatial relationship between the trigeminal nerve and causative vessels. The responsible arteries were identified from the 3-D reconstructed images, which closely simulated the microscopic operative view.

CONCLUSION

3-D reconstructions from two types of high-resolution magnetic resonance images (3-D-CISS and 3-D-FISP) are very useful for creating preoperative simulations and in deciding whether to perform surgery in patients with trigeminal neuralgia.

Trigeminal Nerve-Blood Vessel Relationship as Revealed by High-resolution Magnetic Resonance Imaging and Its Effect on Pain Relief after Gamma Knife Radiosurgery for Trigeminal Neuralgia

OBJECTIVE

Blood vessel (BV) compression of the trigeminal nerve (Cranial Nerve [CN] V) is a common cause of trigeminal neuralgia (TN). High-resolution magnetic resonance imaging scans obtained during gamma knife radiosurgery (GKRS) in patients with TN may be used to analyze the BV-CN V relationship. Follow-up data from a large series of patients treated with GKRS for TN were used to provide information regarding the BV-CN V relationship and pain relief.

METHODS

T1-weighted, axial 1-mm-thick volume acquisition magnetic resonance imaging scans were obtained through the area of CN V at its exit from the brainstem after injection of 15 ml of gadolinium. The BV-CN V relationship on the symptomatic side that was treated with GKRS was categorized into the following groups: Group 1 (no close relationship), Group 2 (BV close to CN V but not touching it), and Groups 3 and higher (BV-CN V contact).

RESULTS

A total of 181 symptomatic nerves were studied in 179 patients with TN who were treated with GKRS. In BV-CN V Groups 1, 2, and 3 and higher, respectively, were 43 sides (24%), 31 sides (17%), and 107 sides (59%). In 100 sides where there was no surgical procedure before GKRS, 50% or greater pain relief was more likely in those with BV-CN V contact (51 [88%] of 58 sides) than in those without BV-CN V (29 [69%] of 42 sides) (P = 0.024). BV-CN V contact was observed more often in men (55 [69%] of 80 sides) than in women (52 [52%] of 101 sides) (P = 0.023) and more often in patients who had unilateral TN (104 [62%] of 169 patients) rather than bilateral TN (2 [20%] of 10 patients) (P = 0.016).

CONCLUSION

In patients who have not undergone previous surgery for TN, BV-CN V contact revealed by high-resolution magnetic resonance imaging may indicate a particularly favorable response to GKRS.

Trigeminal neuralgia and other neuropathic pain syndromes of the head and face

Trigeminal neuralgia is the most common craniofacial pain syndrome of neuropathic origin. Although the diagnosis remains based exclusively on history and symptomatology, modern diagnostic techniques, particularly high-resolution magnetic resonance imaging, provides valuable new insight into the pathophysiology of these cases with additional implications for therapeutic strategies. Other neuropathic syndromes affect the trigeminal nerve and warrant different treatments with varied rates of success. Rarely, neuralgias of other cranial nerves mimic trigeminal neuralgia. Finally, it is imperative to distinguish atypical facial pains from these neuropathic syndromes to avoid unsuccessful therapies.

Superior oblique myokymia: magnetic resonance imaging support for the neurovascular compression hypothesis

Superior oblique myokymia is a rare movement disorder thought to be caused by vascular compression of the trochlear nerve. Direct display of such neurovascular compression by magnetic resonance imaging has been lacking. The goal of this study was to assess the presence of neurovascular contacts in patients with superior oblique myokymia, using a specific magnetic resonance imaging protocol. A total of 6 patients suffering from right superior oblique myokymia underwent detailed neuro-ophthalmological examination, which showed tonic or phasic eye movement. All patients underwent magnetic resonance imaging, using a magnetic resonance imaging Fourier transform constructive interference in steady-state sequence in combination with magnetic resonance imaging time of flight magnetic resonance arteriography both before and after the administration of Gd-DTPA. With this protocol, the trochlear nerve could be visualized on 11 of 12 sides (92%). Arterial contact was detected at the root exit zone of the symptomatic right trochlear nerve in all 6 patients (100%). No arterial contact was identified at the root exit zone of the asymptomatic left trochlear nerve in any of the 5 left nerves visualized. In conclusion, superior oblique myokymia can result from neurovascular contact at the root exit zone of trochlear nerve, and therefore should be considered among the neurovascular compression syndromes.

Clinical review: the differential diagnosis of pain in the quiet eye

BACKGROUND

Eye pain, periorbital and retro-orbital pain, and headache or facial pain referred to the orbital region are common presenting complaints.

REVIEW SUMMARY

In this review, we discuss the etiologies of eye pain in the quiet eye, which is defined clinically as one with a clear cornea without redness or irritation of the conjunctiva or sclera.

CONCLUSIONS

The causes of eye pain may be divided into two groups: (1) those associated with abnormal localizing ophthalmologic and neuro-ophthalmologic findings (including trigeminal neuropathies);(2) those with a normal ophthalmologic and neurologic examinations. The latter group is further divided into the following subgroups: (1) specific short-lasting or long-lasting headache or eye pain syndromes; (2) pain referred to the eye from other pathologic processes (secondary eye pain) sometimes distant from structures concerned with vision; and (3) pain from orbital, superior orbital fissure, cavernous sinus, or intracranial infiltrative, neoplastic, or inflammatory disease processes with normal ophthalmologic and neuro-ophthalmologic exam. Unfortunately, in some patients, no etiology for the pain syndrome is discerned and one is left with a diagnosis of idiopathic eye pain, eye strain, or atypical facial pain.

Diagnosis and differential diagnosis of trigeminal neuralgia

Trigeminal neuralgia is a chronic facial pain classified as a neuropathic pain. There is widespread agreement regarding the International Association for the Study of Pain definition of classical idiopathic trigeminal neuralgia as "a sudden, usually unilateral, severe, brief, stabbing, recurrent pain in the distribution of one or more branches of the fifth cranial nerve." However, there are variations in presentation that are less easy to diagnose and an erroneous diagnosis of trigeminal neuralgia is occasionally made. In patients with tumors or multiple sclerosis, trigeminal neuralgia is termed secondary. Currently, clinical manifestations are the mainstay for diagnosis because there are no objective tests to validate the diagnosis. The sensitivity and specificity of these clinical manifestations is reviewed. Magnetic resonance imaging (MRI) and three-dimensional fast-in-flow with steady-state precession MRI are performed to determine the presence of tumors or plaques of multiple sclerosis and to assess possible compressions and deformations of the trigeminal nerve. Their specificity and sensitivity regarding compressions found at the time of surgery is reviewed. Other differential diagnoses for chronic unilateral orofacial pain are discussed.

Microvascular decompression

Microvascular decompression (MVD) remains the only treatment of trigeminal neuralgia that directly addresses the presumed pathogenesis. It is a proven therapy, associated with the longest duration of pain relief while preserving facial sensation. The authors' premise for advocating early MVD is the belief that the disease's natural progression, in the absence of treatment, is toward the development of more atypical features that are refractory to treatment, signifying ongoing neuropathic injury. In an effort to more successfully select candidates for MVD, the authors have incorporated high-resolution magnetic resonance imaging into our preoperative algorithm, since it has proven extremely accurate in defining the neurovascular relations at the trigminal nerve complex. Microvascular decompression can only be recommended when it is performed with low rates of morbidity.

Advanced magnetic resonance imaging techniques for patients with hemifacial spasm

PURPOSE

To review the underlying causes, diagnostic issues, and treatment of hemifacial spasm, with emphasis on advanced MRI techniques.

METHODS

Brief technical note.

RESULTS

High-resolution T1- and T2-weighted spin-echo and/or gradient echo imaging of the posterior fossa should be performed with the use of intravenous gadolinium for maximum contrast between CSF, vessel, and nerve. Magnetic resonance angiography is often useful, and new state-of-the-art sequences provide more detail.

CONCLUSIONS

As MRI techniques improve, diagnosis and treatment of patients with hemifacial spasm will become easier. Ophthalmologists should be aware of these new magnetic resonance techniques.