Pain Characteristics of the Posterior Longitudinal Ligament in Percutaneous Endoscopic Lumbar Discectomy and its Significance: A Retrospective Study.

INTRODUCTION: In percutaneous endoscopic lumbar discectomy (PELD), pain occurs when the posterior longitudinal ligament (PLL) is exposed, removed, and decompressed. However, pain characteristics of the PLL stimulated in PELD have not been reported.

METHODS: A total of 932 patients underwent PELD under local anesthesia. Pain distribution and intensity were recorded on a posterior body diagram during the operation. Pain intensity was assessed by the visual analog scale scores for the back (VAS-B). The PLL specimens were collected and observed using hematoxylin-eosin (HE) staining and immunohistochemistry.

RESULTS: Patients with lumbar disc herniation (LDH) at L4/5 and L5/S1 had pain foci in different regions. The mean VAS-B scores between the ventral and dorsal sides of the PLL were 6.14 ± 0.97 and 4.80 ± 1.15, respectively (P < 0.05). The distribution of nociceptive nerve fibers in the dorsal side was uniform and scattered, while those in the ventral side were mainly distributed near the outer surface of the annulus fibrosus. The positive expression of substance P (SP) and calcitonin gene-related peptide (CGRP) was higher in the ventral side of the PLL than in the dorsal side (P < 0.0001).

CONCLUSIONS: Differences in pain distribution and intensity were observed when the PLL was incited at different spinal levels during PELD surgery.