Complementary Fluoroscopic Guided Approach to Target the Foramen Ovale in Percutaneous Trigeminal Rhizotomy

Background: Percutaneous cannulation of the foramen ovale to reach gasserian ganglion has been extensively discussed, starting with Hartel`s free hand approach to intraoperative imaging by CT or fluoroscopy, stereotaxy and neuronavigation techniques. Objective: We describe a technique to locate the foramen ovale by fluoroscopy and approach it in a real time fluoroscopic view using Hartel`s entry point and oblique submental view. Patients and Methods: A consecutive series of thirty patients treated in Suez Canal University Hospital between 2012 and 2015. The patient lies supine on fluoroscopic table, and moderate turn toward contralateral side of the target. We marked the Hartel`s entry point with a needle tip then obtain submental view of the skull. The foramen ovale was located and the foramen was cannulated in tunnel view. The impedance was measured (normal 200- 350) and threshold painful stimulation (accuracy is 0.8V) was used as indicator for accuracy of the target. Results: The immediate pain-relief was achieved in twenty nine patients who underwent radiofrequency trigeminal ablation. During the follow-up period two patients (6.6%) experienced recurrence of pain and reablation was done. The mean cannulation time was 11.9 min ±6.5, the mean threshold painful stimulation was 0.39 V ± 0.23 and the mean impedance was 288 Ohm ±47. Dysthesia occurred in 6 patients (20%), however, there was no permanent cranial nerve palsy or morbidity. Conclusion: Real time fluoroscopy provides safe and accurate method to locate the trigeminal ganglion in relatively short time with feasible non expensive facilities.