Microdecompression for Extraforaminal L5-S1 Disc Herniation; The Significance of Concomitant Foraminal Disc Herniation for Postoperative Leg Pain

Objective : To analyze the relationship of concomitant foraminallumbar disc herniation (FLDH) with postoperative leg pain after microdecompression for extraforaminallumbar disc herniation (EFLDH) at the L5-S1 level. Methods : Sixty-five patients who underwent microdecompression for symptomatic EFLDH at the L5-S1 level were enrolled, According to the severity of accompanying FLDH, EFLDH was classified into four categories (Class I : no FLDH; Class II : mild to moderate FLDH confined within a lateral foraminal zone; Class III : severe FLDH extending to a medial foraminal zone; Class IV : Class III with intracanalicular disc herniation). The incidence of postoperative leg pain, dysesthesia, analgesic medication, epidural block, and requirement for revision surgery due to leg pain were evaluated and compared at three months after initial surgery. Results : The incidences of postoperative leg pain and dysesthesia were 36.9% and 26.1%, respectively. Pain medication and epidural block was performed on 40% and 41.5%, respectively, Revision surgery was recommended in six patients (9.2%) due to persistent leg pain, The incidences of leg pain, dysesthesia, and requirement for epidural block were higher in Class III/IV, compared with Class I/II. The incidence of requirement for analgesic medication was significantly higher in Class III/IV, compared with Class I/II (p=0,02, odds ratio=9,82). All patients who required revision surgery due to persistent leg pain were included in Class III/IV. Conclusion : Concomitant FLDH seems related to postoperative residual leg pain after microdecompression for EFLDH at the L5-S1 level.