Lidocaine is an effective local anesthetic that is injected for dental procedures, minor surgeries, as well as nerve blocks, including nerve blocks for migraines, cluster, and other types of headaches. Since it is a numbing medicine, lidocaine has been also given intravenously in the hope of relieving widespread pain or pain that does not respond to local injections. Unfortunately, it is not as effective intravenously as it is for local injections and nerve blocks for either headaches or other pain conditions.
A controlled study of intravenous lidocaine for pain was just published by Korean researchers in the Regional Anesthesia and Pain Medicine – “Efficacy and Safety of Lidocaine Infusion Treatment for Neuropathic Pain: A Randomized, Double-Blind, and Placebo-Controlled Study“.
The researchers decided to examine whether pain relief from intravenous lidocaine can be sustained through repeated lidocaine infusions. This was a randomized, double-blind, placebo-controlled study of infusions of lidocaine (3 mg/kg of lidocaine administered over 1 hour) vs infusions of normal saline, given once a week for 4 consecutive weeks in patients with postherpetic neuralgia or complex regional pain syndrome (formerly called RSD, or reflex sympathetic dystrophy). The results were assessed by the change in pain score from baseline to after the fourth infusion and then again, 4 weeks later.
Forty-two patients completed this study and the percentage reduction in pain scores after the final infusion was significantly greater in the lidocaine group compared with the saline group. However, this pain reduction was not detectable at the 4-week follow-up. None of the study participants experienced serious complications from the treatment.
So, while repeated lidocaine infusions did provide effective short-term pain relief, the effect did not persist.
I have had several of my patients with severe chronic migraines respond to intravenous lidocaine, but their experience was similar – they had to get weekly infusions to maintain good relief. Because intravenous lidocaine can cause irregular heart beat (arrhythmia), cardiac monitoring is required. This makes weekly intravenous lidocaine infusions even more expensive and impractical for most pain and headache sufferers.
