Diagnostic value of preoperative Magnetic Resonance Imaging in evaluation of vascular compression of trigeminal nerve in patients with trigeminal neuralgia
Neurovascular compression of the trigeminal nerve by an overlying vessel, mostly at the root entry zone is considered to be the major cause of trigeminal neuralgia (TGN). The most prevalently used operation technique in patients with trigeminal neuralgia is the microvascular decompression (MVD)....
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|Summary:||Neurovascular compression of the trigeminal nerve by an overlying vessel, mostly at the root entry zone is considered to be the major cause of trigeminal neuralgia (TGN). The most prevalently used operation technique in patients with trigeminal neuralgia is the microvascular decompression (MVD). Peter Jannetta was the first neurosurgeon to apply the operating microscope to the problem of TGN and devised a technique for nondestructive MVD of the nerve. Decompression of the nerve root produces a rapid and long-term relief of symptoms in most patients (80-90%) with vessel-associated TGN. High-Resolution Magnetic Resonance Imaging (HR-MRI) with special sequences: 3D-FSPGR und 3D-FIESTA is used in preoperative evaluation of neurovascular compression in patients with TGN. To assess whether vascular compression of trigeminal nerve in patients with trigeminal neuralgia could be demonstrated reliably by preoperative HR-MRI and how high is the correspondence among MRI results and intraoperative findings in a single blinded study with retrospective analysis after deblinding. We examined preoperatively thirty (30) patients with TGN with HR-MRI using 3D-FIESTA (three-dimensional fast imaging employing steady-state acquisition) and double-dose contrast enhanced 3DFSPGR (three-dimensional fast spoiled gradient-recalled) sequences. These images and postprocessed multiplanar reconstruction (MPR) images were analyzed and later compared with intraoperative videoobservations. Afterwards these results were evaluated in a retrospective analysis of the same MR-images. In all 30 cases the trigeminal nerve could be seen clearly in the 3D-FSPGR sequence. The MPR provided very good images to evaluate the fifth cranial nerve. By injection of double dose of Gadolinium-DTPA even small vessels showed a good enhancement to distinguish them from the surroundings. The 3D-FIESTA sequence, additionally performed in 13 patients, was also able to show the spatial relationships between the structures brilliantly. In 13 of 30 patients (43.33%) preoperative HR-MRI demonstrated the neurovascular compression in good agreement with the intraoperative findings. The noted suspicious side of pathology and also the affected region of trigeminal nerve were in accordance with the intraoperative findings in 12 of 13 cases. The assessment of preoperative HR-MRI concerning the side of neurovascular compression failed in 8 of 30 cases (26.67%). In 9 remaining patients the postoperative results turned out to be different as neurovascular compression: demyelination lesion, Teflon® interponate from previous operation, or neither preoperative MRI on the affected side, nor intraoperative observations demonstrated neurovascular compression with evident TGN, so termocoagulation was performed. So in total preoperative HR-MRI demonstrated the neurovascular condition in good accordance with the intraoperative observations in 19 of 30 patients (63.33%). MRI failed in 11 of 30 cases (36.67%). The HR-MRI with special sequences could be objective, especially when clinical data are not blind to neuroradiologists. In order to get more precise results, the usage of both high-resolution MR sequences should be a condition. Although the HR-MRI is not absolutely reliably in order to show neurovascular compression, the neurosurgeons still prefer to have preoperatively the 3D-FSPGR and 3D-FIESTA images, thus knowing clinically the affected side they are able to improve preoperative preparations and intraoperative expectations.|