| BackgroundTrigeminal neuralgia (TN) is a kind of common disease, whose morbidity is182per10million person, more women than men, which tends to rise with age.70%～80%of patients are over the age of40.The clinical hallmark of trigeminal neuralgia is a sudden, excruciating paroxysm of pain in the distribution of the trigeminal. Due to the severe pain, hard to bear, this disease can seriously influence the patient’s work and daily life. More over, it can reduce the quality of the patients’life, eventually led to psychology abnormity, even suicide. For the serious disease, researchers have never stopped researching. With the development of the microsurgical technique and medical imaging, vascular compression of the central axons of the trigeminal nerve, typically at the root entry zone near the pons (REZ), has been inferred to be a possible cause of TN in most patients. This opinion has been approved by many researchers since Janetta point out the microvascular compression opinion.Objective1. To assess the feasibility and utility of high-resolution contrast-enhanced three-dimensional spoiled gradient recalled (3D SPGR) sequence in the visualization of neurovascular compression (NVC) in patients with trigeminal neuralgia (TN) preoperatively.2. To evaluate the relationship between clinical symptoms related to trigeminal branches and vessels related to the site of trigeminal nerve compression (medial, lateral, cranial and caudal) preoperatively. 3. To preoperatively assess the value of high-resolution three-dimensional magnetic contrast-enhanced3D SPGR sequence in combination with3D TOF MRA for identifying the nature of offending vessel (artery or vein).Methods1. Thirty-seven patients (21males,16females; the age ranged from26to81years with a mean of55.3) with unilateral typical TN received cranial MRI examination using GE3.0T MRI scanner with head coil.Vascular contact with the trigeminal nerve at the 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.2. MR pulse sequence include transverse T2WI(TR5000/TE106,6.0thk/1.0sp); T1WI(TR550/TE15,6.0thk/1.0sp); DWI(TRshortest/TE74,b=1000,6.0thk/1.0sp); T2FAIR(TR8600/TE167/TI2100,6.0thk/1.0sp);contrast-enhanced(Gd-DTPA,0.1m mol/kg)3D SPGR sequence (TR8.6/TE3.4,12°flip angle,240×240-mm field of view,512×512matrix, one acquisition,1.2thk);3D TOF MRA(TR22/TE3.2,15°flip angle,240×240-mm field of view,256×512matrix, one acquisition,1.2thk).3. Statistical analysis was performed by using the commercial software SPSS for windows release11.5(SPSS Inc., Chicago, IL, USA). P values of less than0.05were considered statistically significant. Agreement between preoperative MR image visualization and surgical findings was assessed using the Kappa (K) statistic. A K value of less than0.40was considered to reflect poor agreement, that of0.40-0.59to reflect fair agreement, that of0.60-0.74to reflect good agreement, and that of0.75or more to reflect excellent agreement.Results1. In37patients with TN, surgically verified36caused by neurovascular contact. And contrast-enhanced3D SPGR sequence identified35of these symptomatic nerves. Based on surgical findings, the sensitivity of MR imaging was97.2%and the specificity100%. 2. 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 (κ=0.81;95%confidence interval,0.56～1.00).3. Twelve (85.7%) of14patients with symptoms related to the maxillary division had their NVC at the medial site of the REZ. Thirteen (81.3%) of16patients 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 (P0.001).4. A trend toward increased compression severity on the symptomatic nerve was observed. Compression and contact were showed more frequently on the symptomatic side compared with the asymptomatic side (Fisher exact test, P<0.0001), however no statistically significant differences were found between the asymptomatic side of TN patients and the control group (χ2=0.08, P=0.77).5. In28patients in whom the artery was found to be the responsible blood vessel at surgery, all of these vessels were detected by MR imaging except a very small artery embedded in the nerve. In six patients in whom the vein was confirmed as the conflicting vessel at surgery, all of these vessels were only demonstrated on contrast-enhanced3D SPGR images but not on3D TOF MRA. In another two patients in whom both the vein and the artery were determined to be the compressing vessels at surgery, MR imaging result was consistent with surgical findings in one case. Agreement between the results of MR imaging and the findings at surgery was excellent (k=0.92;95%confidence interval,0.67-1.00).6. In the control group, arterial contact with the trigeminal nerve was shown by MR image in15sides and venous contact in4sides. There were not statistically significant differences in the identification of the vascular nature between the symptomatic side of TN patients and the control group (Fisher exact test, P=0.61).Conclusion 1. High-resolution contrast-enhanced3D SPGR sequence is useful in the detection of NVC in patients with trigeminal neuralgia. It can be useful in predicting surgical findings and providing valuable information for therapeutic schedule:(1) it is helpful in displaying the compressing vessel relative to the trigeminal nerve typically at the root entry zone near the pons;(2) defined the position (medial, lateral, cranial, and caudal) of he compressing vessels.2. Contrast-enhanced3D SPGR sequence in combination with3D TOF MRA are useful in the detection of the nature of offending vessel (artery or vein),high sensitivity and specificity, which can provide valuable information for MVD planning and predicting exact information about the surgical effect. |
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