The micrometric multiarray technique for percutaneous thermocoagulation of trigeminal neuralgia. Preliminary report.

This report describes the technical features and preliminary results of a multiple electrode array system designed to provide access to four different sites within one or more selected trigeminal divisions. At each segment, multiple clinical sensory and motor data are correlated with radiological landmarks in the individual patient with trigeminal neuralgia. The system consists of an outer needle, through which a multielectrode array is introduced. Four successive 2.9 mm caps at the distal end of the multielectrode protrude from the tip of the outer needle into the cerebrospinal fluid of the post-gasserian fibers. The outer needle is always introduced fluoroscopically or tomographically into the inner third of the oval foramen. No blind punctures or suboptimal positions are accepted. After correlating clinical verbal and motor responses at each cap and inter se, the safest location is selected, with a precise knowledge of the segment of the division lying in front and behind the target. Lesions in the first division, the motor division, and segments not involved with pain are avoided. A thermocouple fitted with a micromanipulator allows the placement of the active tip at the center of the chosen target. The maximal size of the lesion cannot exceed the size of the target. Data from 117 consecutive procedures were systematically recorded in a computerized protocol for future analysis. Corneal anesthesia and deafferentation pain were not observed in this series. Preliminary data suggests that the micrometric technique may significantly minimize the residual morbidity from percutaneous thermocoagulation of trigeminal neuralgia.