Evaluation Of 3.0 Tesla Magnetic Resonance Tomographic Angiography In The Diagnosis Of Vascular Compressive Trigeminal Neuralgia And Hemifacial Spasm

Objective: To study the clinical value of 3-tesla magnetic resonance tomographic angiography (MRTA) in the diagnosis of vascular compressive trigeminal neuralgia (TN) and hemifacial spasm (HFS). Methods:16 patients with TN and 25 patients without TN, 36 patients with HFS and 25 patients without HFS were examined by magnetic resonance imaging (MRI) and MRTA. Oblique sagittal and coronal views of trigeminal and facial nerves were created by using original images to display their relationships with the surrounding vessels. Two independent radiologists performed blinded evaluations of connections of the root exit zone (REZ) of trigeminal and facial nerves with their surrounding vessels, and recorded the origin and course of the offending vessels simultaneously. The results were analyzed by SPSS 13.0. Five of the patients with HFS underwent micro-vascular decompression (MVD). Results: (1) In the patients with TN studied, neurovascular compression or contact of the REZ of the trigeminal nerves existed in 12 sides (75%) and uncertain vascular contact in 3 sides (18.6%) in symptomatic sides, 1 (6.3%) and1(6.3%) sides in asymptomatic sides; neurovascular compression or contact existed in 2 sides (4%) in the control group. In the patients with HFS studied, neurovascular compression or contact of the REZ of the facial nerves was detected in 27 sides (75%) and uncertain vascular contact in 4 sides (11.1%) in symptomatic sides, 2(5.6%) and 2(5.6%) sides in asymptomatic sides; neurovascular compression or contact was detected in 3 sides (6%) in the control group. The comparison of the symptomatic sides and asymptomatic sides had significant difference in both TN patients (after Fisher accurate probability law computation , P<0.001) and HFS patients (χ2=40.5, P<0.001). (2) The common offending vessels compressing the REZ of the trigeminal nerves were the superior cerebellar artery (SCA) in 13 sides (86.7%), the anterior inferior cerebellar artery (AICA) in 1 sides (6.7%), and the difficult identified vessels (DIV) in 1 sides (6.7%). The common offending vessels compressing the REZ of the facial nerves were the anterior inferior cerebellar artery (AICA) in 11 sides (35.5%), the posterior inferior cerebellar artery (PICA) in 9 sides (29%) and the vertebral artery (VA) in 7 sides (22.6%). (3) The relative risks (RR) of microvascular compressions which caused TN and HFS were 49.74 and 13.71. Conclusion: 3-tesla MRTA appears to be the best imaging technology for the etiological diagnosis of essential trigeminal neuralgia (TN) and hemifacial spasm (HFS) at present. The major causes of TN and HFS may be neurovascular compressions or close contacts in the REZ of the trigeminal and facial nerves in symptomatic sides. MRTA original images, oblique sagittal and coronal reconstruction are sensitive to neurovascular compression, and able to demonstrate the relationship of the cisternal segment of trigeminal and facial nerves with the surrounding vascular structures. They provide reliable imaging evidence for etiological diagnosis of TN and HFS as well as for clinical preoperative assessment of MVD.