Tolosa-Hunt syndrome: focus on MRI diagnosis

Experience with modem neuroimaging techniques, computed tomography (CT) and magnetic resonance imaging (MRI) scans, in the diagnosis of Tolosa-Hunt sy ndrome (THS) is reviewed. Conventional CT scan remains normal in about two- thirds of these patients. In the reported 22 patients meeting the IHS crite ria for a THS diagnosis on whom an MN study was performed, MRI revealed a c onvex enlargement of the symptomatic cavernous sinus by an abnormal tissue isointense with gray matter on short TR/TE images at-id isohypointense on l ong TR/TE images. This abnormal tissue markedly increases in signal intensi ty after contrast injection. MN seems also to be the ideal technique to fol low progressive resolution of the abnormal tissue after steroids. Therefore , normal MN would probably exclude THS, whereas in the appropriate clinical setting of steroid-responsive painful ophthalmoplegia, MRI showing the cav ernous sinus abnormality described here suggests a diagnosis of THS. From t hese data, we propose that the fourth VIS criterion for THS diagnosis, "Exc lusion of other causative lesions by neuroimaging and (not compulsory) caro tid angiogram" should be changed to "Finding by MRI of specific cavernous s inus abnormalities (with the characteristics described herein) which slowly resolve with steroid treatment".