Trigeminal neuralgia: differentiation between intracranial mass lesions and ordinary vascular compression as causative lesions.

We investigated 164 patients who presented with trigeminal neuralgia as their initial symptom at our institute. Twenty-two patients (13.4%) had intracranial causative lesions other than vascular compression. There were 19 tumors (10 epidermoids, 5 meningiomas, and 4 neurinomas) and 3 vascular lesions (2 arteriovenous malformations and 1 aneurysm). Eleven patients (50%) demonstrated only trigeminal neuralgia without any other neurological deficits. Preoperative computed tomography could not identify any causative lesions in 6 of these 22 patients. In 3 of the 6 patients, a causative lesion was clearly detected only by magnetic resonance imaging, while in 1 of the 6 patients an arteriovenous malformation was detected by angiography alone. Intraoperatively tumor was encountered in 3 cases even though preoperative computed tomography could not detect any apparent causative lesions. A higher incidence of hypesthesia in the trigeminal nerve regions as well as a reduced corneal reflex was noted in patients with a mass lesion compared to those with vascular compression. We thus conclude that magnetic resonance imaging should be performed on all patients who complain of trigeminal neuralgia in order to rule out mass lesions, however, angiography is still considered useful for the diagnosis of some vascular lesions.