A Comparative Study Between Preoperative MRI And Intro-Operative Findings In Trigeminal Neuralgia And Hemifacial Spasm Associated To Vascular Compression

Objective To evaluate the the clinical significance of preoperative MRI in diagnostic value of vascular compression and guidance of operation for trigeminal neuralgia(TN) and hemifacial spasm(HFS).Methods Preoperative MRI manifestations of 43 patients with trigeminal neuralgia and hemifacial spasm were reviewed retrospectively.3D-TOF-SPGR sequence were used in all patients,The oblique sagittal and coronal views of the bilateral trigeminal nerves and facial nerves were reconstructed based on the original images for observing the relationship between cranial nerves(facial nerve and trigeminal nerve) and peripheral vessels, especially whether there was vascular compression of the cranial nerve,the difference between the symptomatic sides and asymptomatic sides was compared.MRA were reconstructed by maxiumintensity projection(MIP) for observing the sources of offending vessels.MRVE was performed using 3D-CISS images(source images) suitable for 3D reconstructions in 6 patients to display the spatial structure between the offending vessels and nerves,twelve cases of them were compared with microvascular decompression surgery.Results Fourteen sides had vascular compression or contact at MR imaging in thirty-six sides of the trigeminal nerves of eighteen patients with trigeminal neuralgia,three sides had uncertain vascular contact.Fifteen sides showed vascular compression,contact or uncertain contact in these eighteen sides related symptoms and signs.The difference between the symptomatic sides and asymptomatic sides was statistically significant(P＜0.05).eighteen sides had vascular compression or contact at MR imaging in fifty sides of the facial nerves of twenty-five patients with hemifacial spasm,seven sides had uncertain vascular contact,twenty-two sides showed vascular compression,contact or uncertain contact in these twenty-five sides related symptoms and signs.The difference between the symptomatic sides and asymptomatic sides was statistically significant(P＜0.05).seven trigeminal neuralgia and five hemifacial spasm patients received MVD.Among them,vascular compression was found in the REZ of trigeminal nerve in four cases by preoperativ MRI and five cases intra-operation;vascular compression was found in the REZ of facial nerve in five cases by preoperativ MRI and five,cases intra-operation;The sensitivity, specificity of MR diagnosis of vascular compression or contact was 90%,100 %,respectively,offending vessels found in nine cases by preoperativ MIP images were coincidence intra-operation;the complex anatomic structure in the CPA and spatial relationships between vessels and cranial nerves were reappeared well in six cases by preoperativ MRVE images.Conclusion MRI imaging provide more useful information concerning the etiology of trigeminal neuralgia and hemifacial spasm than any other available diagnostic modalities.It displays the relationship between cranial nerves (trigeminal nerve and facial nerve) and peripheral vessels.Preoperativ MRI had higher specificity and sensitivity in diagnosing vascular compression or contact, MIP images display the sources of offending vessels,Preoperativ MRVE post-processing can provide the excellent spatial structure between the vessels and nerves,There is important value in the etiological diagnosis of vascular compressive trigeminal neuralgia and hemifacial spasm.Furthermore,the MRI is an important tool for neurosurgeons in planning and optimizing microvascular decompression surgery.