Gesichtshautdurchblutung als nicht-invasiver Biomarker zur Bestätigung der Elektrodenpositionierung während der Thermokoagulation des Ganglion Gasseri

Accurate electrode positioning during thermocoagulation of the trigeminal ganglion is crucial to maximize pain relief. Previously, we demonstrated the safety and feasibility of laser speckle imaging (LSI) for facial perfusion imaging during stimulation of the Gasserian ganglion (GG) in humans. This study investigated the clinical relevance of LSI during GG thermocoagulation and its association to outcome.

In this prospective observational study, 21 patients underwent 25 unilateral procedures for refractory trigeminal neuralgia. Under general anesthesia, an LSI device was positioned perpendicular to the face and skin perfusion was continuously recorded at 25 Hz. Continuous LSI measurements were performed at baseline, fluoroscopic needle placement, electrical stimulation (motor test), and thermocoagulation. Real-time facial perfusion was visualized and quantitatively analyzed within ipsilateral and contralateral V1/2/3 regions of interest, and perfusion changes were correlated with clinical outcomes.

LSI was successfully performed in all procedures without adverse events. Compared to baseline, skin perfusion significantly increased across all dermatomes during the procedure (needle placement: 50.2±9.3%, motor test: 48.7±8.3%, thermocoagulation: 48.8±8.6%; p<0.03 vs. baseline). Longitudinal comparisons of these three measurements revealed no differences in perfusion changes (p>0.06). The observed perfusion increase patterns were similar on the treated and untreated sides (p>0.32) and the perfusion increase did not differ based on whether the motor test induced a contraction of the masseter muscle or not (p>0.19). At 4-week follow-up, quality of life was significantly improved compared to preoperatively (SF-36, p<0.001), especially in the sub-domain bodily pain (p<0.0001), but no correlation was found between perfusion changes and outcome (Spearman´s rho -0.05 to 0.1).

During thermocoagulation of the trigeminal ganglion, facial skin perfusion determined by LSI increased significantly after needle placement, which may serve as a non-invasive biomarker for confirmation of correct electrode positioning. The predictive value of perfusion changes regarding outcome needs to be determined in randomized efficacy trials.