Trigeminal neuralgia caused by compression from arteries transfixing the nerve. Report of three cases

The Superior Cerebellar Artery: Variability and Clinical Significance

The superior cerebellar artery (SCA) arises from the distal part of the basilar artery and passes by the oculomotor, trochlear, and trigeminal nerves. SCA is known to play a crucial role in the development of trigeminal neuralgia. However, due to its anatomical variability, it may also trigger other neurovascular compression (NVC), including hemifacial spasm, oculomotor nerve palsy, and ocular neuromyotonia. Additionally, it may be associated with ischemic syndromes and aneurysm development, highlighting its clinical significance. The most common anatomical variations of the SCA include duplication, a single vessel origin from the posterior cerebral artery (PCA), and a common trunk with PCA. Rarely observed variants include bifurcation and origin from the internal carotid artery. Certain anatomical variants such as early bifurcation and caudal course of duplicated SCA trunk may increase the risk of NVC. In this narrative review, we aimed to examine the impact of the anatomical variations of SCA on the NVCs based on papers published in Pubmed, Scopus, and Web of Science databases with a snowballing approach. Our review emphasizes the importance of a thorough understanding of the anatomical variability of SCA to optimize the management of patients with NVCs associated with this artery.

Microvascular decompression in trigeminal neuralgia with the offending artery transfixing the nerve: a case report

Background

An anterior inferior cerebellar artery (AICA) that crosses the right trigeminal nerve is an uncommon arterial anatomic variation. In this anatomical position, it is difficult to separate or move the offending blood vessels and nerves. We report an uncommon case of trigeminal neuralgia (TN) caused by compression of the trigeminal ganglion by a branch of the AICA.

Case presentation

A 34-year-old man with 5 years history who complained of pain on the right side of the face (area V1). The symptoms gradually worsened, and the pain episodes became intense and frequent. Magnetic resonance imaging (MRI) of the cerebrum showed a small blood vessel passing through the right trigeminal nerve. Microvascular decompression (MVD) was performed,because medication was ineffective. Intraoperative exploration confirmed that the vessel which was a branch of the AICA passing through the right trigeminal nerve. As while the artery was temporarily clipped, electrophysiological monitoring showed a decrease in the amplitude of nerve activity. As the artery was considered too important to be sacrificed, the space between the nerves was enlarged mildly, the artery was liberated, the Teflon implant was shredded and placed between the artery branches and nerve to make the blood vessels as perpendicular as possible to the nerve. The patient had no neurological dysfunction and no pain after 8 months of follow-up.

Conclusion

MVD is an effective treatment for artery-induced trigeminal nerve compression, but we report a novel procedure that avoids the complication of facial numbness caused by cutting the offending vessels and incision of the trigeminal nerve.

Microvascular decompression for abducens nerve palsy due to neurovascular compression from both the vertebral artery and anterior inferior cerebellar artery: A case report

Background

Neurovascular compression is an extremely rare etiology of isolated abducens nerve palsy. We describe a successfully treated case of isolated abducens nerve palsy due to sandwich-type compression by the vertebral artery (VA) and anterior inferior cerebellar artery (AICA).

Case Description

A 30-year-old man presented with a 6-month history of horizontal diplopia without other symptoms. Magnetic resonance imaging (MRI) demonstrated pinching of the left abducens nerve between the elongated left VA and left AICA. MRI showed no abnormal findings in the brainstem, cavernous sinus, or orbit. Surgery was performed using a standard lateral suboccipital approach. The abducens nerve was found to be severely compressed from both sides by the VA and AICA, with marked indentation. First, the VA was transposed and fixed to the dura mater of the petrous bone using a Teflon sling with the dripping of fibrin glue. Next, because of limited mobilization due to penetration of the AICA into the nerve, the AICA transfixing the nerve was attached to the pons with Teflon felt and fibrin glue to move the AICA away from the main trunk of the abducens nerve. The abducens nerve palsy gradually improved and eventually resolved by 4 months after the operation.

Conclusion

When an elongated vertebrobasilar artery is identified as the offending vessel on high-resolution MRI, microvascular decompression can be carefully considered as a treatment option for patients with isolated abducens nerve palsy.

Patterns and variations in microvascular decompression for trigeminal neuralgia

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

Presurgical evaluation of hemifacial spasm and spasmodic torticollis caused by a neurovascular conflict from AICA with 3T MRI integrated by 3D drive and 3D TOF image fusion: A case report and review of the literature

Background:

Hemifacial spasm (HS) and spasmodic torticollis (ST) are well-known disorders that are caused by a neurovascular conflict. HS is characterized by irregular, involuntary muscle contractions on one side of the face due to spasms of orbicularis oris and orbicularis oculi muscles, and is usually caused by vascular compression of the VII cranial nerve. ST is an extremely painful chronic movement disorder causing the neck to involuntary turn to the side, upward and/or downward. HS is usually idiopathic but it is rarely caused by a neurovascular conflict with the XI cranial nerve.

Case Description:

We present a case of a 36-year-old woman with a 2-year history of left hemifacial spasm and spasmodic torticollis. Pre-surgical magnetic resonance imaging MRI examination was performed with 3TMRI integrated by 3Ddrive and 3DTOF image fusion. Surgery was performed through a left suboccipital retrosigmoid craniectomy. The intraoperative findings documented a transfixing artery penetrating the facial nerve and a dominant left anteroinferior cerebellar artery (AICA) in contact with the anterior surface of the pons and lower cranial nerves. Microvascular decompression (MVD) was performed. Postoperative course showed the regression of her symptoms.

Conclusions

Transfixing arteries are rarely reported as a cause of neurovascular conflicts. The authors review the literature concerning multiple neurovascular conflicts.

Outcomes of Gamma Knife surgery for trigeminal neuralgia secondary to vertebrobasilar ectasia

OBJECT

Vertebrobasilar ectasia (VBE) is an unusual cause of trigeminal neuralgia (TN). The surgical options for patients with medically refractory pain include percutaneous or microsurgical rhizotomy and microvascular decompression (MVD). All such procedures can be technically challenging. This report evaluates the response to a minimally invasive procedure, Gamma Knife surgery (GKS), in patients with TN associated with severe vascular compression caused by VBE.

METHODS

Twenty patients underwent GKS for medically refractory TN associated with VBE. The median patient age was 74 years (range 48-95 years). Prior surgical procedures had failed in 11 patients (55%). In 9 patients (45%), GKS was the first procedure they had undergone. The median target dose for GKS was 80 Gy (range 75-85 Gy). The median follow-up was 29 months (range 8-123 months) after GKS. The treatment outcomes were compared with 80 case-matched controls who underwent GKS for TN not associated with VBE.

RESULTS

Intraoperative MR imaging or CT scanning revealed VBE that deformed the brainstem in 50% of patients. The trigeminal nerve was displaced in cephalad or lateral planes in 60%. In 4 patients (20%), the authors could identify only the distal cisternal component of the trigeminal nerve as it entered into the Meckel cave. After GKS, 15 patients (75%) achieved initial pain relief that was adequate or better, with or without medication (Barrow Neurological Institute [BNI] pain scale, Grades I-IIIb). The median time until pain relief was 5 weeks (range 1 day-6 months). Twelve patients (60%) with initial pain relief reported recurrent pain between 3 and 43 months after GKS (median 12 months). Pain relief was maintained in 53% at 1 year, 38% at 2 years, and 10% at 5 years. Some degree of facial sensory dysfunction occurred in 10% of patients. Eventually, 14 (70%) of the 20 patients underwent an additional surgical procedure including repeat GKS, percutaneous procedure, or MVD at a median of 14 months (range 5-50 months) after the initial GKS. At the last follow-up, 15 patients (75%) had satisfactory pain control (BNI Grades I-IIIb), but 5 patients (25%) continued to have unsatisfactory pain control (BNI Grade IV or V). Compared with patients without VBE, patients with VBE were much less likely to have initial (p = 0.025) or lasting (p = 0.006) pain relief.

CONCLUSIONS

Pain control rates of GKS in patients with TN associated with VBE were inferior to those of patients without VBE. Multimodality surgical or medical management strategies were required in most patients with VBE.

Visualization of Vascular Compression of the Trigeminal Nerve With High-Resolution 3T MRI: A Prospective Study Comparing Preoperative Imaging Analysis to Surgical Findings in 40 Consecutive Patients Who Underwent Microvascular Decompression for Trigeminal Neuralgia

BACKGROUND:

High-resolution three-dimensional (3D) magnetic resonance imaging (MRI) has demonstrated its ability to predict fine trigeminal neurovascular anatomy.

OBJECTIVE:

To address the predictive value of 3-Tesla (3T) MRI in detecting and assessing features of neurovascular compression (NVC), particularly regarding the degree of compression exerted on the root, in patients who underwent microvascular decompression (MVD) for classic primary trigeminal neuralgia.

METHODS:

This prospective study includes 40 consecutive patients who underwent MVD for classic primary trigeminal neuralgia. All patients underwent a preoperative 3T MRI with 3D T2-weighted driven equilibrium (DRIVE), 3D time-of-flight (TOF) magnetic resonance angiography (MRA), and 3D T1-weighted gadolinium-enhanced sequences in combination. Evaluations were performed by 2 independent observers and compared with the operative findings.

RESULTS:

For prediction of NVC, image analysis corresponded with surgical findings in 39 cases. Of the 3 patients in whom image analysis did not show NVC, 2 did not have NVC at the time of intraoperative observation. MRI sensitivity was 97.4% (37/38), and specificity was 100% (2/2). The kappa coefficients (κ) for predicting the offending vessel, its location, and the site of compression were 0.882, 0.813, and 0.942, respectively. Image analysis correctly defined the severity of the compression in 31 of the 37 cases. The κ coefficients predicting the degree of compression were 0.813, 0.833, and 0.852, respectively, for Grades 1 (simple contact), 2 (distortion), and 3 (marked indentation).

CONCLUSION:

3T MRI using 3D T2-weighted DRIVE in combination with 3D TOF-MRA and 3D T1-weighted gadolinium-enhanced sequences proved to be reliable in detecting NVC and in predicting the degree of root compression, the outcome being correlated with the latter.

Microvascular Decompression in the Treatment of Trigeminal Neuralgia Caused by Vertebrobasilar Ectasia

BACKGROUND

Vertebrobasilar ectasia (VBE) is a rare cause of trigeminal neuralgia (TN). It occurs in about 2% of all patients.

OBJECTIVE

This study reviewed the clinical features, radiological concomitants, and surgical findings of VBE and evaluate the microsurgical decompression procedure as a surgical line of treatment of the associated TN.

METHODS

Ten patients with TN caused by VBE and treated by microvascular decompression are the subject of this study. The study consisted of 6 men and 4 women with a mean age of 54 years. The mean duration of symptoms was 4.5 years. TN was the only symptom in 6 patients; it was associated with hemifacial spasm in 4. Arterial hypertension was present in 6 patients. Multiplanar high-resolution magnetic resonance imaging showed the accurate location and course of the ectatic vessel. Magnetic resonance angiography and digital subtraction angiography confirmed the diagnosis. Surgery demonstrated fifth nerve compression by an ectatic and tortuous vertebrobasilar artery in all cases and seventh nerve compression in 4 cases. Teflon felt was placed between the ectatic artery and compressed nerves.

RESULTS

There was complete resolution of TN in 8 patients (80%) and hemifacial spasm in 3 (75%) without medication. Four of 6 hypertensive patients (66.7%) achieved normotension without medication. There was no recurrence of symptoms in the mean follow-up period of 7.8 years.

CONCLUSION

Microvascular decompression is recommended for the treatment of TN caused by VBE if medical treatment has failed, if the patient is suitable for general anesthesia, and if there is evidence of vascular compression of the trigeminal nerve on magnetic resonance imaging.

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.

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.

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.

Microanatomy of the Central Myelin-Peripheral Myelin Transition Zone of the Trigeminal Nerve

OBJECTIVE:

The aim of this study was to evaluate the microanatomy of the central myelin-peripheral myelin transitional zone (TZ) in trigeminal nerves from cadavers.

METHODS:

One hundred trigeminal nerves from 50 cadaver heads were examined. The cisternal portion of the nerve (from the pons to Meckel's cave) was measured. Horizontal sections were stained and photographed. The photomicrographs were used to measure the extent of central myelin on the medial and lateral aspects of the nerve and to classify TZ shapes.

RESULTS:

The cisternal portions of the specimens ranged from 8 to 15 mm long (mean, 12.3 mm; median, 11.9 mm). The data from the photomicrographs revealed that the extent of central myelin (distance from pons to TZ) on the medial aspect of the nerve (range, 0.1–2.5 mm; mean, 1.13 mm; median, 1 mm) was shorter than that on the lateral aspect (range, 0.17–6.75 mm; mean, 2.47 mm; median, 2.12 mm).

CONCLUSION:

The data definitively prove that the root entry zone (REZ, nerve-pons junction) and TZ of the trigeminal nerve are distinct sites and that these terms should never be used interchangeably. The measurements showed that the central myelin occupies only the initial one-fourth of the trigeminal nerve length. If trigeminal neuralgia is caused exclusively by vascular compression of the central myelin, the problem vessel would always have to be located in this region. However, it is well known that pain from trigeminal neuralgia can resolve after vascular decompression at more distal sites. This suggests that the effects of surgical decompression are caused by another mechanism.

Arteriovenous malformation surrounding the trigeminal nerve--case report

A 57-year-old man presented with subarachnoid hemorrhage due to the rupture of an arteriovenous malformation (AVM) located at the base of the root of the right trigeminal nerve. In contrast to previous similar cases, his history included no evidence of trigeminal neuralgia or sensory loss. Right vertebral artery angiography revealed a doubled superior cerebellar artery feeding the angioma nidus. The patient refused radiotherapy and preferred surgical treatment. Intraoperatively, a close relationship between arterial feeders and rootlets of the trigeminal nerve was observed. Complete removal of the malformation was achieved and confirmed angiographically. The postoperative course was complicated by subdural hygroma that required repeated drainage and eventually a shunting procedure. This case demonstrates that microsurgical treatment of a trigeminal AVM is feasible. However, stereotactic radiosurgery may be the preferred treatment option considering the potential for postoperative complications.

Localized venous plexi in the spine simulating prolapse of an intervertebral disc: a report of six cases

STUDY DESIGN

Six cases are reported in which the clinical presentation of a prolapsed intervertebral disc was found to be caused by a localized venous plexus.

OBJECTIVES

To emphasize the fact that the clinical presentation of a localized plexus of epidural veins in the lumbar spine can resemble that of an acute disc prolapse.

SUMMARY OF BACKGROUND DATA

The finding of enlarged epidural veins during lumbar disc decompression is relatively common, but it is only recently that they have been implicated as the cause of the presenting symptoms.

METHODS AND RESULTS

Six individuals presented with severe pain in the lower back accompanied by sciatica, which had begun acutely. Physical examination in most of these patients showed the presence of neurologic signs in the affected leg. The initial clinical assessment was that of an acute prolapse of a lumbar disc. This diagnosis appeared to be borne out by the MRI scans, which demonstrated a "prolapsed disc" at the relevant level of the spine. However, at surgery, the intervertebral disc appeared to be relatively normal, but at the spine was found a large, localized plexus of epidural veins whose configuration matched the MRI image. The symptoms were relieved by decompression of the spine and ablation of the veins.

CONCLUSIONS

Any pathologic process in the lumbar spine compressing a nerve root can cause localized pain in the back accompanied by sciatica. Most of these conditions can be differentiated by means of an MRI scan. The MRI image of a localized plexus of epidural veins, however, closely resembles that of a prolapsed intervertebral disc, which may be diagnostically misleading.

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.