[Study of facial neuralgia].

So-called idiopathic, essential trigeminal neuralgia is characterised by typical severe pain in the territory of the trigeminal nerve or one of its divisions. This entity remains a diagnosis of exclusion after investigation by computerized tomography and/or magnetic resonance imaging of the path of the trigeminal nerve and its branches, to exclude any neoplastic, inflammatory, infectious or vascular process. Nevertheless, surgical exploration and now medical imaging have revealed in a large number of cases of "idiopathic" essential trigeminal neuralgia, compression of the trigeminal nerve as it emerges from the brainstem by a vascular loop.