Computed Tomography Guidance for Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia

Background Percutaneous glycerol rhizotomy (PGR) is a well-described treatment for trigeminal neuralgia; however, the technique in using surface landmarks and fluoroscopy has not drastically changed since being first introduced. In this paper, we describe a protocol for PGR using computed tomography (CT) guidance based on an experience of over 7 yr and 200 patients. Objective To introduce an approach for PGR using CT guidance and, in doing so, demonstrate possible benefits over the traditional fluoroscopic technique. Methods Using a standard CT scanner, patients are placed supine with head in extension. Barium paste and a CT scout image are used to identify and plan a trajectory to the foramen ovale. A laser localization system built into the CT scanner helps to guide placement of the spinal needle into the foramen ovale. The needle position in the foramen is confirmed with a short-sequence CT scan. Results CT-guided PGR provides multiple benefits over standard fluoroscopy, including improved visualization of the skull base and significant reduction in radiation exposure to the surgeon and staff. Side benefits include improved procedure efficiency, definitive imaging evidence of correct needle placement, and potentially increased patient safety. We have had no significant complications in over 200 patients. CONCLUSION CT-guided PGR is a useful technique for treating trigeminal neuralgia based on better imaging of the skull base, better efficiency of the procedure, and elimination of radiation exposure for the surgeon and staff compared to traditional fluoroscopic based techniques.

The Effect of Medial Displacement Calcaneal Osteotomy on Tarsal Tunnel Volume

Category: Hindfoot Introduction/Purpose: Tarsal tunnel volume is affected by position of the foot and the alignment of the ankle. Although medial displacement calcaneal osteotomy (MDCO) significantly alters the alignment of the hindfoot, the change of tarsal tunnel volume after this procedure has not yet been well documented. Therefore, authors investigated the volumetric change of tarsal tunnel after MDCO using Computed Tomography (CT) scan. Methods: This retrospective study involved 101 feet of 91 patients who underwent a MDCO at our institution from March 2016 to December 2018. We compared the tarsal tunnel volume from the preoperative and postoperative CT scan images under following protocols. On a sagittal scout image, the oblique axial plane was drawn parallel to the long axis of the calcaneus using talonavicular joint as a landmark. Serial oblique axial images were displayed using PACS (PathSpeed, GE Healthcare, Chicago, IL, USA) with both the soft tissue and the bone window settings. The volume of tarsal tunnel was evaluated from just distal to the tip of medial malleolus anterior colliculus to distance of 3 cm distal using 10 consecutive images by drawing the border of tarsal tunnel. The volume was calculated by adding 10 cross-sectional areas and then multiplying by 3 mm corresponding to slice thickness. Results: The mean preoperative and postoperative tarsal tunnel volume were 12229 mm3 (SD, 1842 mm3) and 12762 mm3 (SD, 1803 mm3), respectively. There was 4.6% (SD, 3.4%) of volume increase after MDCO (p <0.001). Results indicated high inter- and intraobserver reliability coefficients (r = 0.97, r = 0.98, respectively). Conclusion: MDCO increased the volume of tarsal tunnel. This finding might support clinicians performing MDCO as a conjunctive surgical option in treating patients with tarsal tunnel syndrome.