Objective: Neuropathic pain is a common secondary complication of spinal cord injury (SCI). N-methyl-D-aspartate (NMDA) receptor activation is critical for hypersensitivity in neuropathic pain. This activation requires the binding of both glutamate and the D-serine co-agonist to the NMDA glycine site. We evaluated the effects of D-serine on neuropathic pain after SCI and explored the underlying molecular mechanisms.Methods: Anesthetized rats underwent T9 spinal cord contusion (130 kdyn). D-serine (500 and 1,000 mg/kg) and MK-801 hydrogen maleate (2.0 mg/kg) were injected daily for 2 weeks, starting the day after SCI. Functional outcomes were assessed according to the Basso, Beattie, and Bresnahan scale, while histological outcomes were evaluated based on lesion volume and spared tissue area. Mechanical allodynia and thermal hyperalgesia were evaluated by measuring the withdrawal threshold of a von Frey filament and hot/cold plate latency. Western blotting was performed to determine the expression levels of Trpv1, Nav1.9, calcitonin gene-related peptide (CGRP), and β-actin in damaged tissue.Results: The withdrawal threshold values and latency of the D-serine group were significantly lower than those of the noninjection group. The MK-801 group showed higher threshold values and latencies than the other groups. Western blotting showed increased Nav1.9 and Trpv1 levels and lower CGRP levels in the D-serine group, whereas the MK-801 group showed the opposite results.Conclusion: D-serine increases neuropathic pain after traumatic SCI by mediating the NMDA receptor. NMDA receptor antagonists alleviate neuropathic pain after traumatic SCI.

Objective: Although several studies have reported successful fusion rates after oblique lumbar interbody fusion (OLIF) using allografts or dimerized bone matrix (DBM) instead of autografts, whether OLIF can achieve satisfactory solid fusion without the use of autografts remains unclear. This study investigated the real fusion rates after OLIF using allografts and DBM, which were evaluated using both dynamic radiographs and computed tomography scans.Methods: We enrolled 79 consecutive patients who underwent minimally invasive OLIF followed by percutaneous pedicle screw fixation. All patients were treated with OLIF between L2 and L5 and underwent radiographic and clinical follow-ups at 12, 18, and 24 months after surgery. Radiographic assessment of fusion was performed using the modified BrantigaSteffee-Fraser (mBSF) scale, which was categorized as follows: grades I (radiographic pseudoarthrosis), II (indeterminate fusion), and III (solid radiographic fusion). Other radiologic and clinical outcomes were evaluated using the following parameters: vertebral slippage distance, disc height, subsidence, Oswestry Disability Index (ODI), and visual analogue scale (VAS).Results: Clinical outcomes demonstrated significant improvements in the VAS scores for back pain, leg pain, and ODI after surgery. Subsidence was present in 34 cases (35.4%) at 12 months postoperatively, which increased to 47.9% and reached 50.0% at 1.5 years and 2 years after surgery, respectively. The solid fusion rate after OLIF was 32.3% at 1 year, increased to 58.3% at 1.5 years, and reached 72.9% at 2 years. Radiographic pseudoarthrosis was 24.0% at 1 year, which decreased to 6.3% at 1.5 years and 3.1% at 2 years.Conclusion: OLIF is a safe and effective surgical procedure for the treatment of degenerative lumbar diseases. The mBSF scale, which simultaneously evaluates both dynamic angles and bone bridge formation, offers great reliability for the radiological assessment of fusion. Moreover, OLIF using allografts and DBM, which is performed on one or 2 levels at L2–5, can achieve satisfactory fusion rates within 2 years after surgery.

Background: Oblique lumbar interbody fusion (OLIF) results in less tissue damage than in other surgeries, but immediate postoperative pain occurs. Notably, facet joint widening occurs in the vertebral body after OLIF. We hypothesized that the application of a facet joint block to the area of widening would relieve facet joint pain. The purpose of this study was to evaluate the analgesic effects of such injections on postoperative pain. Methods: This double-blinded, placebo-controlled study randomized patients into 2 groups. Patients assigned to the active group received an intra-articular injection of a compound mixture of bupivacaine and triamcinolone, whereas patients in the placebo group received an equivalent volume of normal saline solution injection. Back and dominant leg pain were evaluated with use of a visual analog scale (VAS) at 12, 24, 48, and 72 hours postoperatively. Clinical outcomes were evaluated preoperatively and at 6 months postoperatively with use of the Oswestry Disability Index (ODI) and VAS for back and dominant leg pain. Results: Of the 61 patients who were included, 31 were randomized to the placebo group and 30 were randomized to the active group. Postoperative fentanyl consumption from patient-controlled analgesia was higher in the placebo group than in the active group at up to 36 hours postoperatively (p < 0.001) and decreased gradually in both groups. VAS back pain scores were significantly higher in the placebo group than in the active group at up to 48 hours postoperatively. On average, patients in the active group had a higher satisfaction score (p = 0.038) and were discharged 1.3 days earlier than those in the placebo group. Conclusions: The use of an intraoperative facet joint block decreased pain perception during OLIF, thereby reducing opioid consumption and the severity of postoperative pain. This effect was also associated with a reduction in the length of the stay. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Lee SW, et al. Brain Tumor Res Treat. 2021 Oct;9:e23. https://doi.org/10.14791/btrt.2021.9.e23

Jung J, et al. Korean J Neurotrauma. 2024 Dec;20:e39. https://doi.org/10.13004/kjnt.2024.20.e39