[Neuroradiologic diagnosis of trigeminal neurinoma originating from the gasserian ganglion (author's transl)].

Three cases of trigeminal neurinoma originating from the Gasserian ganglion were reported. The findings observed on plain roentgenograms, cerebral angiograms and pneumoencephalograms were described in detail. Neuroradiologic examinations used routinely our department for the diagnosis of the skull base tumors were as follows; (1) plain skull examinations, including lateral, straight posterior-anterior, anterior-posterior half axial (Towne), axial, Stenvers, optic canal as well as tomograms in frontal, sagittal and axial projections; (2) angiographies by transfemoral catheter technique including selective internal carotid, external carotid and vertebral angiograms, and orbital-cavernous sinus venography via frontal and femoral veins; (3) pneumoencephalography with tomography. Bone destruction of the middle fossa including foramen ovale, foraman spinosum and lateral aspect of the sella was seen in all cases. Superior orbital fissure, optic canal and anterior surface of the petrous bone were also eroded depending upon the extent of tumors. Sharply circumscribed erosion of the petrous apex was seen in one of 3 cases, indicating the tumor extention into the posterior fossa. A soft tissue mass in the sphenoid sinus and ethmoidal air cells was recognized in all cases. Selective internal and external carotid angiograms demonstrated tumor vessels in 2 of 3 cases. Orbital-cavernous sinus venography was helpful for the interpretation of the lesion extending to the cavernous sinus and its neighboring structures. Conventional gas encephalography showed elevation of the temporal horn, and the concave arch formed by the supracornual cleft and lateral cleft was directed basally and medially in all of the cases. Tomography was also useful in the more detailed analysis of temporal horn. It should be stressed that the plain skull features are most important for deciding which contrast examination should be performed further.