IV ketamine and IV lignocaine are emerging treatment options for complex regional pain syndrome (CRPS), particularly in cases that are refractory to conventional therapies. Both drugs work through distinct but complementary mechanisms to help manage pain and improve function.
IV Ketamine for CRPS
- Mechanism of Action: Ketamine is an NMDA receptor antagonist that helps in reducing central sensitization and neuropathic pain. CRPS is associated with central sensitization, and ketamine helps to reset this abnormal pain processing.
- Evidence: Studies have shown that low-dose IV ketamine infusions can provide significant pain relief in CRPS patients, with effects lasting beyond the infusion period.
- Protocol: Typically, ketamine is administered as an infusion over multiple days at subanesthetic doses (e.g., 0.1-0.5 mg/kg/h).
- Side Effects: Dissociation, hallucinations, dizziness, nausea, and potential blood pressure elevation.
IV Lignocaine for CRPS
- Mechanism of Action: Lignocaine is a sodium channel blocker that stabilizes nerve membranes, reduces ectopic discharges, and has anti-inflammatory effects.
- Evidence: IV lignocaine has been shown to reduce neuropathic pain in CRPS by modulating pain transmission.
- Protocol: Administered as an IV infusion (e.g., 1-5 mg/kg over 30-60 minutes).
- Side Effects: Lightheadedness, dizziness, numbness, arrhythmias (rare at therapeutic doses).
Comparison & Synergistic Use
- Both target different pain pathways and may be used in combination for enhanced pain relief.
- Ketamine is preferred for severe CRPS cases with central sensitization, while lignocaine is beneficial for neuropathic pain and allodynia.
- A combination therapy approach may provide better pain relief while minimizing the dose of each drug, reducing side effects.
Conclusion
IV ketamine and IV lignocaine are promising treatments for CRPS, particularly in refractory cases. Their use should be carefully monitored in a hospital setting to ensure safety and efficacy. While both have strong evidence supporting their use, more research is needed to establish optimal protocols.
