Neurovascular Compression In Patients Research Articles

Commentary: Neurovascular Compression in Patients With Trigeminal Neuralgia May Be Associated With Worse Outcomes After Primary Percutaneous Rhizotomy.

Commentary: Neurovascular Compression in Patients With Trigeminal Neuralgia May Be Associated With Worse Outcomes After Primary Percutaneous Rhizotomy.

Neurovascular Compression in Patients With Trigeminal Neuralgia May Be Associated With Worse Outcomes After Primary Percutaneous Rhizotomy

BACKGROUND AND OBJECTIVES: Percutaneous rhizotomy may be an effective primary intervention in patients with trigeminal neuralgia who are poor candidates for microvascular decompression or those who desire a less invasive approach. However, the influence of neurovascular compression on pain-free survival after primary percutaneous rhizotomy is not well understood. METHODS: We retrospectively reviewed all patients undergoing percutaneous rhizotomy at our institution from 1995 to 2022. Patients were included if they had no history of surgical intervention, available preoperative MRI imaging, and postoperative follow-up data. Barrow Neurological Institute pain scores were assigned at various time points. We collected baseline patient information, pain characteristics, and perioperative complications for each patient. In addition, we recorded evidence of pain recurrence. Patients were dichotomized into those with evidence of neurovascular compression on preoperative MRI vs those without. The effect of neurovascular compression on pain-free survival was assessed using Kaplan-Meier Cox proportional hazards analyses. RESULTS: Of the 2726 patients reviewed, 298 met our inclusion criteria. Our study comprised 261 patients with no evidence of neurovascular compression on preoperative MRI vs 37 patients with evidence of neurovascular compression on preoperative MRI. Patients in the compression group had a shorter median duration to recurrence compared with those in the no compression group, P = .01. Kaplan-Meier survival analysis revealed that patients with preoperative evidence of neurovascular compression on MRI imaging demonstrated shorter pain-free survival compared with those without such evidence [hazard ratio = 1.57 (1.03-2.4), P = .037]. Cox proportional hazards analysis demonstrated that evidence of neurovascular compression was associated with poor pain-free survival [hazard ratio = 1.64 (1.06-2.53), P = .03]. CONCLUSION: Patients with neurovascular compression on preoperative MRI may experience reduced time to recurrence compared with those without after percutaneous rhizotomy. These patients should be counseled on potential reduced efficacy of percutaneous rhizotomy as a primary intervention for their pain.

3D multimodal image fusion based on MRI in the preoperative evaluation of microvascular decompression: A meta‑analysis.

Neurovascular compression (NVC) is the main cause of hemifacial spasm (HFS) or trigeminal neuralgia (TN), and frequently occurs at the root entry zone of cranial nerves. Microvascular decompression (MVD) is an effective surgical treatment for TN and HFS caused by NVC. The accurate preoperative diagnosis of NVC is crucial to the evaluation of MVD as an appropriate treatment for TN and HFS. Three-dimensional (3D) time-of-flight magnetic resonance angiography (3D TOF MRA) and high resolution T2-weighted imaging (HR T2WI) are used to detect NVC prior to MVD; however, this combination alone has certain disadvantages. Multimodal image fusion (MIF) may combine two or more images from the same or different modalities, allowing neurosurgeons to use the reconstructed 3D model to observe anatomical details more clearly from different perspectives. The aim of the present meta-analysis was to evaluate the effect of 3D MIF based on 3D TOF MRA combined with HR T2WI in the preoperative diagnosis of NVC, and thus to evaluate its clinical application value in the preoperative evaluation of MVD. Relevant studies available on PubMed, Embase, Web of Science, Scopus, China National Knowledge Infrastructure and the Cochrane Library, and published from the inception of each database to September 2022, were retrieved. Studies using 3D MIF based on 3D TOF MRA combined with HR T2WI to diagnose NVC in patients with TN or HFS were included. The Quality Assessment of Diagnostic Accuracy Studies checklist was used to evaluate the quality of the included studies. The statistical software Stata 16.0 was used to perform the meta-analysis. Data extraction was performed by two independent investigators and discrepancies were resolved by discussion. Pooled sensitivities, specificities, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and the area under the receiver operating characteristic curve (AUROC) were calculated as the main summary effect size. The I² and Q-test were used to assess heterogeneity. The present search identified 702 articles, of which 7 (comprising 390 patients) fulfilled the inclusion criteria. Bivariate analysis indicated that the pooled sensitivity and specificity of 3D MIF based on 3D TOF MRA combined with HR T2WI for detecting NVC were 0.97 (95% CI, 0.95-0.99) and 0.89 (95% CI, 0.77-0.95), respectively. The pooled PLR was 8.8 (95% CI, 4.1-18.6), the pooled NLR was 0.03 (95% CI, 0.02-0.06) and the pooled DOR was 291 (95% CI, 99-853). The AUROC was 0.98 (95% CI, 0.97-0.99). The studies had no substantial heterogeneity (I2=0; Q=0.000; P=0.50). The present results suggested that 3D MIF based on 3D TOF MRA combined with HR T2WI had excellent sensitivity and specificity for diagnosing NVC in patients with TN or HFS. Therefore, this method should serve a key role in MVD preoperative evaluation.

Different MRI-based methods for the diagnosis of neurovascular compression in trigeminal neuralgia or hemifacial spasm: A network meta-analysis

BackgroundAccurate preoperative diagnosis of neurovascular compression (NVC) is crucial in the treatment of trigeminal neuralgia (TN) or hemifacial spasm (HFS). At present, there are many magnetic resonance imaging (MRI)-based methods for diagnosing NVC in clinical practice. This network meta-analysis (NMA) aimed to evaluate the diagnostic performance of different MRI-based imaging methods for NVC in patients with TN and HFS. Materials and methodsRelated studies based on a search of PubMed, Embase, Web of Science and the Cochrane Library were retrieved. A two-way analysis of variance model was constructed for the Bayesian NMA to compare the performance of different diagnostic imaging methods. ResultsOur search identified 595 articles, of which 26 studies (including 2085 patients) related to 4 diagnostic imaging methods (3D time-of-flight magnetic resonance angiography (3D TOF MRA), high resolution T2-weighted imaging (HR T2WI), 3D TOF MRA combined with HR T2WI, and 3D multimodal image fusion (MIF) based on 3D TOF MRA combined with HR T2WI) were included in this NMA. The results showed that 3D MIF based on 3D TOF MRA combined with HR T2WI had the highest related sensitivity, the highest superiority index and the largest area under the receiver operating characteristic curve among all the methods. Conclusions3D MIF based on 3D TOF MRA combined with HR T2WI had better diagnostic performance for detecting NVC in patients with TN or HSF than other MRI-based imaging methods. This method can be used as an effective tool for preoperative evaluation of MVD.

Three-dimensional time-of-flight magnetic resonance angiography combined with high resolution T2-weighted imaging in preoperative evaluation of microvascular decompression.

Neurovascular compression (NVC) is the main cause of primary trigeminal neuralgia (TN) and hemifacial spasm (HFS). Microvascular decompression (MVD) is an effective surgical method for the treatment of TN and HFS caused by NVC. The judgement of NVC is a critical step in the preoperative evaluation of MVD, which is related to the effect of MVD treatment. Magnetic resonance imaging (MRI) technology has been used to detect NVC prior to MVD for several years. Among many MRI sequences, three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) is the most widely used. However, 3D TOF MRA has some shortcomings in detecting NVC. Therefore, 3D TOF MRA combined with high resolution T2-weighted imaging (HR T2WI) is considered to be a more effective method to detect NVC. To determine the value of 3D TOF MRA combined with HR T2WI in the judgment of NVC, and thus to assess its value in the preoperative evaluation of MVD. Related studies published from inception to September 2022 based on PubMed, Embase, Web of Science, and the Cochrane Library were retrieved. Studies that investigated 3D TOF MRA combined with HR T2WI to judge NVC in patients with TN or HFS were included according to the inclusion criteria. Studies without complete data or not relevant to the research topics were excluded. The Quality Assessment of Diagnostic Accuracy Studies checklist was used to assess the quality of included studies. The publication bias of the included literature was examined by Deeks' test. An exact binomial rendition of the bivariate mixed-effects regression model was used to synthesize data. Data analysis was performed using the MIDAS module of statistical software Stata 16.0. Two independent investigators extracted patient and study characteristics, and discrepancies were resolved by consensus. Individual and pooled sensitivities and specificities were calculated. The I² statistic and Q test were used to test heterogeneity. The study was registered on the website of PROSERO (registration No. CRD42022357158). Our search identified 595 articles, of which 12 (including 855 patients) fulfilled the inclusion criteria. Bivariate analysis showed that the pooled sensitivity and specificity of 3D TOF MRA combined with HR T2WI for detecting NVC were 0.96 [95% confidence interval (CI): 0.92-0.98] and 0.92 (95%CI: 0.74-0.98), respectively. The pooled positive likelihood ratio was 12.4 (95%CI: 3.2-47.8), pooled negative likelihood ratio was 0.04 (95%CI: 0.02-0.09), and pooled diagnostic odds ratio was 283 (95%CI: 50-1620). The area under the receiver operating characteristic curve was 0.98 (95%CI: 0.97-0.99). The studies showed no substantial heterogeneity (I2 = 0, Q = 0.001 P = 0.50). Our results suggest that 3D TOF MRA combined with HR T2WI has excellent sensitivity and specificity for judging NVC in patients with TN or HFS. This method can be used as an effective tool for preoperative evaluation of MVD.

Extent and Location of Neurovascular Compression in Patients with Hemifacial Spasm

Hemifacial spasm (HFS) is characterized by involuntary contraction of muscles innervated by the ipsilateral facial nerve. Generally, it initially

Is MVD the effective treatment for poorly controlled hypertension?

BackgroundStudies have shown that microvascular decompression (MVD) surgery could improve the clinical symptoms of hemifacial spasm (HFS) and decrease the blood pressure (BP) in patients with refractory hypertension. More positive long-term results are required to establish MVD as a treatment option for high blood pressure (HBP) and to refine the patient selection criteria. MethodsFrom October 2015 to September 2018, based on patient selection for cases with both HFS and poorly controlled HBP of nervous origin, MVD surgeries were performed on 12 patients aiming for better BP control. The patients were followed-up for at least 2 years. The surgical outcomes and associated factors were analyzed. ResultsWith respect to neurovascular compression (NVC) of facial nerve, the intra-operative findings concurred with pre-operative radiological findings except that in one case. Intra-operatively ipsilateral cranial nerve (CN) IX–X root exit zone (REZ) and rostral ventrolateral medulla (RVLM) NVCs were confirmed and concordant with pre-operative radiological findings in all 12 cases. 9 Of the 12 cases were completely free of facial spasm after surgery. 2 patients achieved partial relief. 1 patient still suffered from frequent facial spasm. 10 out of 12 patients achieved BP lowering after surgery. The BP of those 10 patients stayed at a relatively stable scale over the follow-up period. Although statistical significance was not obtained, for patients who are operated on the left side and those who have only 1 offensive artery, the surgery might lead to better BP control. ConclusionsMVD is a safe and effective treatment for hypertension due to central nervous system (CNS) NVC in patients with both HBP and HFS. Further studies are required to examine long-term outcomes and establish criteria for patient selection.

Neurovascular Relations of the Trigeminal Nerve in Asymptomatic Individuals Studied with High-Resolution Three-Dimensional Magnetic Resonance Imaging.

Neurovascular compression (NVC) is considered the main cause of classic trigeminal neuralgia (TN) and may be surgically addressed with microvascular decompression (MVD). Preoperative high-resolution three-dimensional magnetic resonance has proven a reliable tool to diagnose NVC in patients with refractory TN undergoing MVD. However, there is still scarce data regarding the rate, degree, and characteristics of neurovascular compression in asymptomatic individuals. This article describes the vascular relations of the trigeminal nerve in the cerebellopontine angle (CPA) in 100 subjects without known TN studied with 3.0T FIESTA (Fast Imaging Employing Steady-state Acquisition) MRI sequence. A NVC was observed in 142 (71%) of the 200 nerves with a 75% rate of bilateral NVC. Of the nerves with NVC, 92.3% showed a mere contact (Grade 1) without distortion and 78% occurred at the cisternal segment. This most common vessel causing the NVC was a vein (66%) followed by the superior cerebellar artery (28%). No significant reduction in diameter suggesting atrophy was seen in the nerves with NVC. The results indicate a high rate of mild, distal and predominantly venous vascular contact with the trigeminal nerve at the CPA in asymptomatic individuals. This clearly contrasts with the usual pattern of NVC observed in TN that is generally a severe, proximal, and arterial compression. Knowledge about the frequent NVC in asymptomatic individuals and its features is essential for interpreting preoperative MRI in patients with refractory classical TN considered for surgery. Anat Rec, 302:639-645, 2019. © 2018 Wiley Periodicals, Inc.

7.0 Tesla MRI tractography in patients with trigeminal neuralgia

7.0 Tesla (T) high-resolution diffusion tensor imaging (DTI) can supply information on changing microstructures in cranial nerves. We investigated DTI parameters and the feasibility of DTI criteria for diagnosing trigeminal neuralgia (TN). In this study, 14 patients (28 hemispheres) of mean age 49.0 years (range, 31–64) with TN underwent DTI using 7.0 TMRI. We compared fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) of affected-side and unaffected-side trigeminal nerves using DTI. We examined associations between DTI parameters and clinical characteristics for patients with TN. In patients with TN, affected sides showed significantly decreased FA and significantly increased MD, and RD compared with unaffected sides of trigeminal nerves. Nuclei were not significantly different among patients with TN. Barrow Neurological Institute (BNI) pain scores did not correlate with affected sides. 7.0 T DTI was useful for detecting neurovascular compression in patients with TN. The increased signal-to-noise ratio provided by 7 T MRI should be advantageous for increasing spatial resolution to detect microstructure changes to trigeminal nerves in patients with TN.

Clinical features and long-term surgical outcomes in 39 patients withtumor-related trigeminal neuralgia compared with 360 patients with idiopathic trigeminal neuralgia

Objective: The purpose of this study was to compare clinical features, long-term surgical outcomes between patients with idiopathic and tumor-related trigeminal neuralgia (TN), and to identify factors associated with the maintenance of permanent pain-free state.Methods: Between January 2003 and December 2013, 360 patients with idiopathic TN and 39 patients with tumor-related TN who had undergone microsurgery were retrospectively studied. Kaplan–Meier survival curves were generated and compared by Log-rank test, and the possible prognostic factors were analyzed by the Cox proportional-hazards regression.Results: Patients with tumor-related TN exhibited a younger age of pain onset (46.28 ± 18.18y vs. 53.03 ± 11.90y, p = .006), a briefer symptom duration (3.20 ± 4.38y vs. 7.01 ± 6.04y, p = .000), and much more preoperative neuropathic deficits (61.54%% vs. 24.17%%, p = .000), as compared with patients with idiopathic TN. Using Kaplan–Meier analysis, we found microsurgery was effective in 72.3% of patients with idiopathic TN, and in 86.4% of cases with tumor-related TN at six years follow-up postoperatively. Prognostic analysis suggested that a clear-cut neurovascular compression in patients with idiopathic TN (HR = 3.098, 95%CI: 1.800–5.311; p = .000) and total tumor removal in patients with tumor secondary TN (HR = 7.662, 95%CI: 0.098–36.574; p = .044) were positively correlated with excellent long-term outcomes.Conclusions: The occurrences of TN at younger age, a shorter duration and preponderance of preclinical neuropathic symptoms are the characteristics of TN patients secondary to intracranial tumor, in contrast to patients with TN caused by a compressed vessel. Microsurgery is an effective and safe treatment modality for TN regardless of the disease etiology, the involvement of a clear-cut vascular offender and total tumor resection are the most important predictors of excellent outcome for microsurgery in idiopathic and tumor-related TN patients, respectively.

A dual concurrent mechanism explains trigeminal neuralgia in patients with multiple sclerosis.

In this clinical and neuroimaging study, we sought information on the possible role of neurovascular compression in multiple sclerosis (MS)-related trigeminal neuralgia (TN). After screening 1,628 consecutive patients with MS, we enrolled 28 patients with definite unilateral MS-related TN. In these patients, we acquired dedicated 3T MRI scans, identified pontine demyelinating plaques, and, using highly specific diagnostic criteria, distinguished possible neurovascular compression. MRI scans in most patients showed a demyelinating plaque in the pontine trigeminal root entry zone on the affected side. The frequency of the neurovascular compression and its association with the pontine demyelinating plaque were higher on the affected than on the unaffected side (54% vs 0%; p = 0.0001). Our observation that in many patients with MS-related TN a pontine demyelinating plaque and neurovascular compression coexist should prompt neurologists to seek possible neurovascular compression in patients with MS-related TN.

Neurovascular compression of medulla oblongata – Association for gestation-induced hypertension

Patients with essential hypertension may show neurovascular compression (NVC) at the rostral ventrolateral medulla oblongata (RVLM). Ectatic loops of the vertebral artery (VA) or the inferior posterior cerebellar artery (PICA) cause NVC. This study aims to show the existence and morphology of NVC in patients with gestation-induced hypertension. 17 females were prospectively examined between 19+0 and 35+6weeks of gestation. 3 patients with chronic hypertension (group A), 10 patients with preeclampsia (group B), 3 patients with superimposed preeclampsia (chronic hypertension with preeclampsia; group C) and one normotensive patient were included. Groups B and C represented patients with gestation-induced hypertension. All 17 patients underwent imaging by high resolution magnetic resonance imaging (MR-CISS, constructive interference in the steady state). Image processing was done with segmentation and three-dimensional (3D)-visualization was implemented with direct volume rendering of the individual neurovascular details of each patient. 9 of 17 patients (53%) showed NVC of the RVLM. Right-sided NVC was seen in 7 patients (41%). Left-sided NVC was seen in 6 patients (35%). Bilateral NVC was seen in 4 patients (24%). NVC was missing in 8 of the examined 17 patients (47%). The existence of NVC with high-resolution MRI was analyzed in gestation-induced hypertensive pregnant females for the first time. Neurovascular conflicts were seen in hypertensive pregnants. It is possible that NVC is potentially associated in patients with gestation-induced hypertension.

Characteristics of neurovascular compression in facial neuralgia patients by 3D high–resolution MRI and fusion technology

ObjectiveTo evaluate the anatomical characteristics and patterns of neurovascular compression in patients suffering trigeminal neuralgia, using 3D high–resolution magnetic resonance imaging methods and fusion technologies. MethodsThe analysis of the anatomy of the facial nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients for TN. 3D high resolution MRI studies (3D SPGR, T1 enhanced 3D MP-RAGE and T2/T1 3D FIESTA) simultaneous visualization were used to assessed using the software 3D DOCTOR. ResultsIn 93 patients (93%), there were one or several locals of neurovascular compression (NVC). The superior cerebellar artery was involved in 71 cases (76%), the other vessels including the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. The mean distance between NVC and nerve origin site in the brainstem was (3.76 ± 2.90) mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). ConclusionsThis 3D high resolution MRI and image fusion technology could be useful for diagnostic and therapeutic decisions in TN.

MR cisternography in the posterior fossa: the evaluation of trigeminal neurovascular compression

To evaluate the utility of 3D-magnetic resonance cisternography(MRC) of posterior cranial fossa in visualizing trigeminal neurovascular compression in patients with trigeminal neuralgia. 146 consecutive patients in the period from June 2010 to July 2011 in our institute diagnosed with trigeminal neuralgia underwent MRC on the posterior cranial fossa. MR devices used for MRC included two sets of 3.0 tesla and one set of 1.5 tesla. The hydrography sequences for MRC included 3D-SPACE and 3D-DRIVE. In total, 75 patients (51.4%) were found with trigeminal neurovascular compression on MRC. Among them, 25 patients underwent microvascular decompression. Intraoperatively, 20 patients (80%) had related arteries consistent with imaging manifestations on MRC. Nevertheless, the arterial compression combined with petrosal vein could not be identified on MRC in 3 of the 20 patients. In the inconsistent 5 cases, the involved vessels were confirmed as superior petrosal veins during the surgery. 3D-MRC has prominent clinical value in determining the trigeminal neurovascular compression and identifying the related vessels. However, MRC does have certain limitations on identifying petrosal vein compression.

Preoperative demonstration of neurovascular compression in trigeminal neuralgia with contrast - enhanced 3D - SPGR sequence

Objective To assess the value of contrast - enhanced three - dimensional spoiled gradient recalled (3D - SPGR ) sequence in the preoperative visualization of neurovascular compression (NVC) in patients with trigeminal neuralgia(TN) and to evaluate the relationship between clinical symptoms of neuralgia related to trigeminal branches and the sites of trigeminal nerve compression.Method Thirty -seven patients(21 males,16 females; the age ranged from 26 to 81 years with a mean age of 55.3 years) with unilateral typical TN underwent preoperative contrast - enhanced 3D - SPGR sequence.The vascular contact with the trigeminal nerve at the root entry zone (REZ) was reviewed by an experienced neuroradiologist,who was blinded to the clinical details.The imaging results were compared with the operative findings and clinical symptoms related to trigeminal branches in patients.Results In 37 patients with TN,contrast - enhanced 3D - SPGR sequence identified surgically verified neurovascular contact in 35 of 36 symptomatic nerves.Based on surgical findings,the sensitivity of MR imaging was 97.2％ and the specificity 100％.Agreement between the position ( medial,lateral,cranial,and caudal) of the compressing vessel relative to the trigeminal nerve defined by MR imaging and findings at surgery was good( K =0.81 ;95％ confidence interval,0.56 ～ 1.00).Twelve(85.7％ ) of 14 patients with symptoms related to the maxillary division had their NVC at the medial site of the REZ.Thirteen(81.3％ ) of 16 patients with symptoms related to the mandibular division had their NVC at the lateral site of the REZ.A statistically significant difference was observed between the NVC site and the clinically manifested symptoms in the branches of the trigeminal nerve( P ＜ 0.001 ).Conclusions Contrast - enhanced 3D - SPGR sequence is useful in detection of NVC in patients with TN.Anatomic relationships defined by this method may be useful in predicting surgical findings. Key words: Magnetic resonance imaging; Microvascular decompression; Neurovascular compression; Trigeminal neuralgia; Comparative studies

Trigeminal neuralgia: Assessment with T2 VISTA and FLAIR VISTA fusion imaging

To evaluate the neurovascular compression (NVC) in patients with trigeminal neuralgia (TN) using T2 VISTA and FLAIR VISTA fusion imaging. Sixty-six consecutive patients with TN who underwent MR imaging at 3-T between April 2008 and December 2010 were retrospectively reviewed. Multiplanar reconstructions (MPR) of T2 VISTA and FLAIR VISTA fusion imaging were used for image interpretation. The frequency of vascular contact, the segment of compression and the type of vessel were compared between the ipsilateral symptomatic side and the contralateral asymptomatic side. The frequency of vascular contact on the ipsilateral side and the contralateral side were 95.5% (63/66) and 74.2% (49/66), respectively. The frequency of indentation on the ipsilateral side and contralateral side were 74.2% (49/66) and 21.2% (14/66), and showed a statistically significant difference (p < 0.05). The sensitivity, specificity and odds ratio were 77.8%, 71.4% and 10.7, respectively. There were no significant differences in the involved segment or type of vessel between the ipsilateral side and contralateral side. MPR of T2 VISTA and FLAIR VISTA fusion imaging is useful in the detection of NVC in patients with TN. Vascular indentation can predict the presence of symptoms in patients with TN. Key Points •Fusion MRI with multiplanar reconstruction can detect neurovascular compression in patients with trigeminal neuralgia •Vascular indentation can predict the presence of symptoms in patients with trigeminal neuralgia •In patients with trigeminal neuralgia, neurovascular indentation is commoner on the symptomatic side.

Relationship Between the Curative Effects of Carbamazepine Administration and the Neurovascular Compression Volume of the Trigeminal Nerve Measured Using Magnetic Resonance Cisternography

To elucidate the relationship between the extent of pain and neurovascular compression (NVC) volume, measured by magnetic resonance (MR) cisternography, in patients with trigeminal neuralgia. In addition, we aimed to evaluate the relationship between NVC volume and the efficacy of carbamazepine administration in patients with trigeminal neuralgia. MR cisternography was performed on 214 patients with clinical signs and symptoms that suggested trigeminal neuralgia retrospectively. The extent of their pain was evaluated using visual analog scales. Next, only carbamazepine was administered as the initial treatment. For the patients with NVC detectable on MR cisternography, the relationship between the extent or nature of the pain and the neurovascular volume was analyzed. In addition, the correlation between the efficacy of carbamazepine treatment and the NVC volume was evaluated retrospectively. Of the 214 patients evaluated, 144 were deemed to have NVC. In these 144 patients, a significant difference was found between the NVC volume and the curative effects of 100 mg/d carbamazepine. However, no significant correlation was found between the extents of pain by visual analog score or between the daily dosage of carbamazepine and the NVC volume measured by MR cisternography. Three-dimensional MR cisternography is very useful for detecting the site of NVC in patients with trigeminal neuralgia. NVC measured by this technique may indicate the prognosis after initial treatment. The present results suggest that the evaluation of NVC volume by MR cisternography would be useful in choosing the initial treatment for patients with trigeminal neuralgia.

Patterns of neurovascular compression in patients with classic trigeminal neuralgia: A high-resolution MRI-based study

To describe the anatomical characteristics and patterns of neurovascular compression in patients suffering classic trigeminal neuralgia (CTN), using high-resolution magnetic resonance imaging (MRI). The analysis of the anatomy of the trigeminal nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients treated with a Gamma Knife radiosurgery for CTN between December 1999 and September 2004. MRI studies (T1, T1 enhanced and T2-SPIR) with axial, coronal and sagital simultaneous visualization were dynamically assessed using the software GammaPlan™. Three-dimensional reconstructions were also developed in some representative cases. In 93 patients (93%), there were one or several vascular structures in contact, either, with the trigeminal nerve, or close to its origin in the pons. The superior cerebellar artery was involved in 71 cases (76%). Other vessels identified were the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. Vascular compression was found anywhere along the trigeminal nerve. The mean distance between the nerve compression and the origin of the nerve in the brainstem was 3.76±2.9mm (range 0-9.8mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). The findings of this study are similar to those reported in surgical and autopsy series. This non-invasive MRI-based approach could be useful for diagnostic and therapeutic decisions in CTN, and it could help to understand its pathogenesis.

Sensitivity of high-resolution three-dimensional magnetic resonance angiography and three-dimensional spoiled-gradient recalled imaging in the prediction of neurovascular compression in patients with hemifacial spasm

Hemifacial spasm is a clinical syndrome caused by vascular compression of the facial nerve in the cerebellopontine angle, which can be relieved by surgical intervention. Advances in medical imaging technology allow for direct visualization of the offending blood vessels in hemifacial spasm and similar conditions (such as trigeminal neuralgia). The utility of high resolution 3D MR angiography and 3D spoiled-gradient recalled (SPGR) imaging sequences for surgical decision-making in hemifacial spasm, as measured by sensitivity, specificity, and positive and negative predictive values, has not been previously determined. A retrospective review was undertaken of 23 patients with hemifacial spasm who underwent operations between January 2001 and December 2006 at Oregon Health & Science University. All patients underwent preoperative high-resolution 3D MR angiography and 3D SPGR imaging. The sensitivity of the SPGR imaging/MR angiography interpretation of neurovascular compression (NVC) by both a neurosurgeon and 2 neuroradiologists was determined in relation to the presence of actual NVC during surgery. All patients were found to have NVC at surgery. After review by a neurosurgeon and 2 neuroradiologists, imaging data from 19 of the 23 patients were evaluated. The neurosurgeon's interpretation had a sensitivity of 79% and a positive predictive value (PPV) of 100%. The first neuroradiologist's interpretation had a sensitivity of 21% with a PPV of 100%. Further interpretation by a blinded second neuroradiologist with expertise in MR imaging of hemifacial spasm and trigeminal neuralgia was conducted, and sensitivity was 59% and PPV was 100%. Specificity was not determined because there were no true negative cases. The negative predictive value was 0% for both the neurosurgeon's and neuroradiologists' evaluations. Although high-resolution 3D MR angiography and 3D SPGR imaging was helpful in providing information about the anatomical relationship of cranial nerve VII and surrounding blood vessels, the authors determined that in the case of hemifacial spasm these types of imaging did not influence preoperative surgical decisionmaking.

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

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. 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. 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. 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.