[Predictive value of MRI for detecting and characterizing vascular compression in cranial nerve hyperactivity syndromes (trigeminal and facial nerves)]. / Valeur prédictive de l'IRM pour la détection et la caractérisation de la compression vasculaire dans les syndromes d'hyperactivité des nerfs crâniens (trijumeau et facial).

ABSTRACT

MRI detects vascular compression of the cranial nerve in the majority of the cases. High-resolution 3D-T1 and 3D-T2 MRI gives detailed images, particularly the 3D-T2 MRI sequences, with good contrast between cerebrospinal fluid and vascular and nerve structures. TOF-AMR (native sequence and vertebrobasilar reconstruction) shows the vascular structures in hypersignal and therefore differentiates the vessels from the cranial nerves. The 3D-T1 sequence with gadolinium reinforces the signal of the venous structures. Thus, preoperative MRI makes it possible to predict the existence of a vascular compression. The correlation study between imaging data and intraoperaitive anatomical findings showed a sensitivity of MRI of 97% and a specificity of 100%. In addition, it can specify the type and the degree of the compression. This information may help in selecting the most appropriate surgical method.