Summary

Distal sodium channel blockers (DSCB) injection for upper limb Neuropathic pain: An out-patient case series of 50 patients and review of literature

Abstract

Introduction

Evidence points toward voltage-gated sodium channels blockers as a key target for novel analgesics. Sodium channel blocker are the class of drugs that act by inhibition of sodium influx through cell membranes. Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitabilities and reduces conduction velocities. Distal sodium channel blockers (DSCB) injection is infiltration of local anaesthetic drugs around nerve sheaths at the most terminal branch along its course, which leads to the sodium channel blocking effect upwards towards the dorsal root ganglia and nerve roots, which produce pain due to excitation after the disease complex.

Objective

To assess the usefulness of DSCB injection in upper limb pain complex diseases of various origins

Method

50 patients of neuropathic upper limb pain with various severity were followed up for a minimum of 6 months. 20 patients of cervical disc lesion with nerve root compression (group 1), 20 patients of adhesive capsulitis (group 3) and 10 patients with overlapping of both diseases (group 3) were included in the study. A mixture of 2 ml 1% Lignocaine, 30 microgram clonidine, 40 milligram 1ml of methylprednisolone acetate injected in first web space of affected limbs two times, one month apart. Assessment is done by visual analogue scale (VAS) pain score and clinical examination. Significant improvement is considered, if VAS score reduces by 5 or more. 30 degree or more, pain-free improvement of range of motion (ROM) is considered significant. Number of analgesics taken per week also enquired.

Results

Patients in Group 1, 2 and 3 had 50%, 60% & 50 %, improvement in VAS score & ROM after first injection and 65%, 75% & 60%, after second injection respectively. 60%, 65% & 50% patients in the respective groups, maintained the improvement at the end of six-month examination for both VAS score & ROM. An average of 3 analgesic medicines per week were consumed by study patients.

Conclusion

DSCB injection is simpler, safer, cheaper and effective out-patient procedure to treat upper limb pain complex of disease of various origins. However, prospective long term multicentric studies with larger sample size, are required to understand how these distal nerve blocks really work. Long term analgesic intake is another area of concern.

Key words: Distal sodium channel blockers, Neuropathic pain, Nerve sheath; Dorsal root ganglia; Pain; Pain relief.