Distal Sodium Channel Block in Managing Lumbosacral Radicular Pain: A Prospective Single-Group Study

Abstract

Background: Lumbosacral radicular pain is a frequent cause of low-back-related disability and may substantially restrict walking, work, sleep, and routine activities. Although most patients improve with conservative treatment, a subgroup experiences persistent or severe radicular symptoms requiring interventional pain management. Epidural and selective nerve-root procedures can provide short-term benefit, but their availability, technical requirements, cost, and procedural risks may limit their use in some clinical settings. Distal sodium channel block (DSCB) represents a peripheral approach based on the concept that nerve-root irritation may produce distal neural hyperexcitability and increased sodium-channel activity along the affected neural pathway. Objective: To evaluate the effectiveness and short-term safety of DSCB in patients presenting with lumbosacral radicular pain involving the L4, L5 and/or S1 dermatomes. Methods: This open-label, non-randomised, single-group prospective study was conducted at Bangladesh Multicare Hospital, Rampura, Dhaka; Tropical Hospital and Diagnostic Centre, Demra, Dhaka; and Holycare Hospital, Nawabganj, Dhaka, Bangladesh, from March 2020 to March 2024. A total of 200 patients with low back pain radiating to the L4/L5/S1 or all three dermatomes and baseline numerical rating scale (NRS) pain intensity >4/10 were included. Baseline NRS and straight leg raise (SLR) findings were recorded before treatment and reassessed at 30 minutes, 24 hours, 1 week, and 4 weeks following DSCB. The injection consisted of 2 mL of 2% plain lignocaine, 1 mL triamcinolone 40 mg, and 7 mL distilled water. A total volume of 2.5 mL was administered at each of the Beta 1, Beta 2, Beta 3, and tau 4 portals. Statistical analysis was performed using SPSS version 21.0. Paired comparisons between baseline and follow-up measurements were assessed, with statistical significance defined as p≤0.05. Results: Among the 200 participants, 114 (57.0%) were female and 86 (43.0%) were male. No serious procedural complications were recorded. Following DSCB, pain intensity decreased and SLR performance improved at 30 minutes, 24 hours, 1 week, and 4 weeks. Comparisons between baseline and follow-up measurements demonstrated statistically significant improvement at every assessment point (p<0.001). The persistence of improvement at 4 weeks suggests that the observed benefit was not limited to the immediate local anaesthetic period. Conclusion: DSCB was associated with significant improvement in pain intensity and SLR findings in patients with lumbosacral radicular pain. The technique is relatively simple, can be performed in an outpatient environment, and may provide rapid symptomatic relief while allowing time for conservative pharmacological treatment and rehabilitation to take effect. Because this was an uncontrolled single-group study, controlled trials with longer follow-up and validated functional outcomes are required before DSCB can be considered an established alternative to conventional spinal interventions.

Keywords: distal sodium channel block; lumbosacral radicular pain; lumbar radiculopathy; sciatica; lignocaine; triamcinolone; straight leg raise; numerical rating scale; peripheral nerve block; pain intervention.