LAUSR

OBJECTIVE Lumbar facet cysts are commonly seen in degenerative lumbar conditions causing stenosis and radiculopathy. Extraforaminal lumbar facet cysts are a rare entity and present a surgical challenge because of their location. Transforaminal endoscopic spine surgery is an emerging technique in spine surgery but has never been described as a treatment option for lumbar radiculopathy in the setting an extraforaminal lumbar facet cyst. METHODS A technique for the transforaminal endoscopic treatment of an extraforaminal lumbar facet cyst is presented in 2 patients. We retrospectively reviewed 321 cases of patients who underwent transforaminal endoscopic surgery in a 4-year period with a minimum follow up of 2 years. RESULTS A series of 2 patients who underwent transforaminal endoscopic foraminotomy and cyst resection procedures for extraforaminal lumbar facet cysts between 2014 and 2017 is presented. A 51-year-old female with a right L4-5 extraforaminal cyst improved from a preoperative visual analog scale (VAS) of 7 and Oswestry disability index (ODI) of 26 to a 1-year postoperative VAS score of 2 and ODI of 4. A 71-year-old with a left L5-S1 extraforaminal cyst improved from a preoperative VAS of 7 and ODI of 30 to a 1-year postoperative VAS score of 2 and ODI of 6. CONCLUSIONS Transforminal endoscopic surgery for a lumbar radiculopathy in the setting of an extraforaminal lumbar facet cyst is presented as a unique minimally invasive approach for the treatment of extraforaminal lumbar facet cyst that avoids facet resection and fusion.