A multiarray electrode mapping method for percutaneous thermocoagulation as treatment of trigeminal neuralgia. Technical note on a series of 178 consecutive procedures.

BACKGROUND: We describe our method and mapping technique of the trigeminal nerve using a quadripolar electrode to minimize morbidity of percutaneous thermocoagulation as treatment of trigeminal neuralgia. METHOD: Of 381 patients selected for postgasserian thermocoagulation, 178 consecutive procedures were carried out using, in most cases, our painless and ambulatory method and technique. All patients were preoperatively subjected to 3-dimensional constructive interference in steady-state magnetic resonance and magnetic resonance angiography. Transgasserian introduction of our quadripolar multiarray electrode under constant fluoroscopic monitoring is used with systematic recording of radiologic angles at, in front of, and behind the clivus profile, always below the selar floor. The individual's somatotopic map based on the verbal responses of 34 facial subsegments in lieu of the usual 3 is carefully established. Lesions are aimed at the trigger of pain and restricted to fibers with the lowest thresholds. Maximal lesions are one third the size used in conventional thermocoagulation. Lesions attempt to avoid damage to the first division, uninvolved fibers, and the motor division. RESULTS: Pre- and postoperatory thresholds demonstrate that trigger-aimed small lesions do not extend to unwanted subsegments. The described technique can minimize unnecessary complications from percutaneous thermocoagulation.