[Trigeminal neuralgia. Percutaneous thermocoagulation of the trigeminal nerve (author's transl)].

200 cases of percutaneous thermocoagulation of the trigeminal nerve were studied in order to determine if the position of the thermolesion in the various parts of the trigeminal system modified the quality of the results and the frequency of post-operative complications. An anatomo-radiological study allowed the precise localisation in the sagittal plane of the position of the different parts of the trigeminal ganglion with respect to the neighbouring bony features. The quality of the results and the frequency of complications were studied according to the level of the thermolesion (ganglion, triangular plexus, posterior sensory root). This study permitted the observation that the more posterior the thermolesion, the less frequent the complication, and this confirmed results obtained in earlier procedures, c.g. gasserian or retro-gasserian neurotomy. Post-operative hypoaesthesia extending beyond the painful area, was the major side-effect of the radicular position of the thermolesion. There follows a discussion of the criteria, which permit the recognition of the point of the electrode at the level of the posterior root: the flow of CSF, vasodilatation, and radiological localisations. Of these three criteria, only radiological demonstration (point of the needle posterior to the clivus and above the petrous temporal bone) seemed reliable.