116. Decompression of far-out syndrome using unilateral biportal endoscopy: surgical techniques and clinical outcome

Abstract

BACKGROUND CONTEXT Surgical access to the L5–S1 extraforaminal region is complicated and the deep location makes the surgery technically challenging and more invasive. For this reason, some previous studies have reported a relatively high rate of persistent or recurrent radiculopathy after microsurgical foraminotomy for far-out syndrome (FOS). For FOS, the biportal endoscopic technique, which can reach deeper into the extraforaminal lesion less invasively, is becoming widespread. PURPOSE The purpose of this study is to present the unilateral biportal endoscopic (UBE) technique for complete decompression of FOS and evaluate 1-year clinical outcomes. STUDY DESIGN/SETTING Retrospective study. PATIENT SAMPLE Between September 2014 and August 2016, we enrolled 35 consecutive patients who underwent a single-level UBE decompression for FOS and could be followed up for at least one year postoperatively. OUTCOME MEASURES Parameters for clinical results [visual analogue scale (VAS) for back and leg pain, Oswestry Disability Index (ODI)], compression factors of FOS (preoperative CT and MRI) and surgical complications (dural tear, nerve root injury, infection, hematoma) were analyzed. METHODS This study evaluated 3 clinical and radiological subjects: (1) clinical results, (2) compression factors of FOS, and (3) surgical complications. The clinical results were evaluated by collecting answers to a questionnaire for outcome scores (VAS for back and leg pain and ODI) preoperatively and one year postoperatively. The compression factors were evaluated using preoperative images as follows: (1) pseudarthrosis between the transverse process of L5 and ala of sacrum, (2) ventral factor (disc bulging or disc bulging with osteophytes), and (3) thickened lumbosacral ligament. The surgical complications were evaluated by the incidence of intraoperative dural tear and nerve root injury, re-operation due to the surgical hematoma, and infection within a year. RESULTS The study group consisted of 16 men and 19 women with an average age at surgery of 68.4 + 6.6 years. The mean follow-up was 15.3 months. Overall operative time ranged from 63 to 135 minutes (mean 78.5 minutes). Concomitant foraminal stenosis was found in 10 cases (28.5%). Mean VAS for back pain was 3.7 + 1.8 before surgery, and this value was decreased to 2.3 + 0.8 at 1-year follow-up postoperatively (p CONCLUSIONS In the present study, we achieved excellent surgical outcomes after the UBE decompression for patients with FOS without complications. UBE decompression can overcome certain technical challenges involved in the conventional procedures for FOS. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.