No single surgical procedure can achieve lasting pain relief in all patients with trigeminal neuralgia. Percutaneous balloon compression trigeminal rhizotomy is an alternative outpatient procedure for patients in whom open operation or other percutaneous procedures are infeasible or have failed. The instrumentation required and a stepwise description of the procedure are given. Limited information on results is available, but suggest that approximately 95% of patients will get immediate relief of their pain with a median duration of pain estimated between 20 and 28 months. As many as 20% of patients may remain pain free and off medication at 5 years. Serious complications are rare but include meningitis, hemorrhage, extensive facial dysesthesia or analgesia and cranial nerve dysfunction.
TopSurgical Procedure
We originally performed the procedure using the Mullan Trigeminal Ganglion Microcompression Set (Cook Medical LLC., P.O. Box 4195 Bloomington, IN 47402-4195). This set is no longer commercially available. We have combined a number of commercially available instruments and supplies to make a usable kit for the procedure (Lim, Ladd, Grande, & Haines, 2017).
The operation is done under general anesthesia. The patient is positioned supine with the neck extended to facilitate modified submento-vertex fluoroscopic views to identify the foramen ovale. Brown and Pilitsis (2005) recommend placing an external pacemaker prior to starting the procedure in the event that trigeminal compression produces asystole. In our experience, with appropriate cholinergic blockade we have never had to use the pacemaker.
The procedure can be done in an operating room, procedure room or imaging facility so long as biplane fluoroscopy is available for guiding the placement of the needle and monitoring balloon inflation shape. We have preferred to use the operating room. One c-arm fluoroscope is positioned for a true lateral image of the skull base (planum spenoidale, sella turcica and clivus) and one for a modified submento-vertex view of the foramen ovale. The surgeon stands on the side of the patient’s pain (and therefore the side of needle placement). The base of the lateral fluoroscope should be opposite the surgeon.
The balloon catheter is prepared by filling it with contrast that is approved for intrathecal use (in case the balloon ruptures). The appropriate depth of passage of the balloon catheter through the cannula is determined visually, fixed by a friction adapter and measurements made so that depth can be confirmed after the passage of the balloon catheter.
Various external landmarks are used to guide the initial placement of cannula and should be marked before draping. The needle puncture site is generally 2.5 cm lateral to the oral fissure. The landmarks of 3 cm anterior to the external auditory meatus along the inferior edge of the zygomatic process and the midpupillary line are generally attributed to Hartel (Abdennebi & Guenane, 2014). With good success, we have used the “upside-down ventriculostomy” landmarks of half the distance from the external auditory canal to the lateral canthus of the eye and the midpupillary line.
In either case, the skin is sterilely prepped and the insertion site puncture with a large gauge needle or fine blade. The 11 gauge cannula is passed through the entry point toward the foramen ovale. The surgeon places one finger in the oral cavity during the initial passage to be alerted to penetration of the oral cavity which should result in discarding the contaminated cannula and starting over. After the initial placement to the skull base, gloves are changed and AP and lateral fluoroscopic images obtained. The trajectory is adjusted to place the tip of the cannula in the foramen ovale.
A stylet is passed through the cannula to make pathway for the balloon catheter. Depth and position of the stylet penetration is monitored fluoroscopically. Once satisfactory position is obtained (the balloon typically rests with its proximal edge at the clival line) the stylet is removed and replaced with the balloon catheter. The inflation syringe is attached.