Use of sensory and motor action potentials to identify the position of trigeminal nerve divisions for radiofrequency thermocoagulation

Abstract

Object The objective of this study was to develop an electrophysiological method for intraoperative localization of the trigeminal nerve branches during radiofrequency thermocoagulation (RFTC). Methods Twenty-three patients who were scheduled to undergo RFTC were included. The trigeminal nerve root was stimulated through the foramen ovale using the radiofrequency cannula. Antidromic responses were recorded from the target division through supraorbital, infraorbital, and mental foramina electrodes, and an additional electrode at the masseter muscle. Sensory and motor action responses, as well as verbal and masseter contraction responses, were recorded and correlated. Results The antidromic responses were easily recorded in the target division in all 23 patients, and they were invariably correlated with the patient's verbal responses. The potentials were recorded successively from V1 to V3. The amplitude in each division before and after RFTC showed little difference in response to electrical stimulation with the same current. The motor trigeminal nerve action potentials were recorded in 10 patients; 7 of these patients had postoperative masseter muscle weakness, while the remaining 3 had normal masseter muscle function. Potentials with low amplitudes were usually obtained from neighboring divisions, but no unexpected denervation of any branches was observed. All the patients experienced immediate pain relief after the procedure. Conclusions This technique is sensitive and easy to apply. The sensory and motor potentials matched the verbal responses and the complications. Although it cannot completely substitute for the patient's verbal response, this approach is helpful in uncooperative patients, and it predicts and reduces the incidence of masseter muscle weakness. The use of these complementary techniques could increase the chances of treatment success.

Computed Tomography‐Guided Percutaneously Controlled Ablation of the Thoracic Paravertebral Nerve Due to Thoracic Neuropathic Pain

“…Furthermore, it may not be possible to locate the thoracic paravertebral nerve based on anatomy, even when combined with CT guidance in each patient. Therefore, coblation devices with an electrical stimulation mode must be developed to improve safety and effectiveness, such that sensory and motor action potentials can be monitored throughout the procedure . Additional clinical experience and controlled studies are necessary for further evaluation of the effect of coblation on the management of thoracic neuropathic pain.…”

Treatment of bilateral idiopathic trigeminal neuralgia by radiofrequency thermocoagulation at different temperatures

“…[16,38] This finding indicates that RFT at temperatures >75°C may increase the risk of masticatory atonia. Meanwhile, the rate of masticatory atonia was only 4.8% at 68°C, which was far lower than that after RFT at a higher temperature and is consistent with that reported by Wael, [22] who performed RFT at 60°C to 70°C.…”

“…We instructed patients to gradually reduce oral drugs (e.g., carbamazepine) that they had been using preoperatively during several days postoperatively before discontinuing them. Therefore, the long-term follow-up was started at discharge, while in previous reports [14,16,21,22] the follow-up was started immediately after operation, which influenced the accuracy of postoperative observation. There were 5 and 3 patients who had no pain relief or rated outcomes as unsatisfactory during the postoperative hospital stay, and all of them had secondary RFT before discharge.…”

“…[16–18] However, upon clinical application of RFT at 75°C to 80°C, a large number of patients experienced facial numbness, masticatory atonia, and other complications, which is not concurrent with the preclinical findings. [5] There has been controversy in the recent literature regarding the suitable temperature for RFT in TN.…”

Laser speckle imaging to improve clinical outcomes for patients with trigeminal neuralgia undergoing radiofrequency thermocoagulation

“…Recently, electrophysiological recordings of retrograde sensory and motor action potentials have been used to locate the position of the thermocoagulation probe relative to the different trigeminal nerve divisions. 13 Such recordings may provide a useful tool to investigate further the relationship between areas of blood-flow changes and innervation territory. Alternatively, in animal studies, one could mark the stimulation site within the trigeminal ganglion/branches (e.g., by producing a small lesion) to investigate postmortem whether the stimulated and marked branch indeed innervated the areas in which an increase in blood flow was seen.…”