Background and Objectives It has been found that 5% lidocaine with 7.5% dextrose causes irreversible conduction block in animal studies. Our case report subjects allowed us to observe the efficacy of 5% lidocaine for a prolonged analgesia in vivo.

Method After performing a diagnostic nerve block with 1% lidocaine, 5% lidocaine with 7.5% dextrose was injected into three patients with trigeminal neuralgia, post-herpetic occipital neuralgia, and intercostal neuralgia, respectively. The patients were followed for one and a half years. Visual Analog Scale (VAS) scores and the side effects were recorded for each patient.

Results One patient received a trigeminal block and one patient received an occipital nerve block. Both patients reported immediate and complete pain relief lasting 14 and 8 months, respectively. One patient, given an intercostal nerve block, received immediate pain relief lasting 5 weeks. None of these patients exhibited any appreciable side effects or complications.

Conclusions Our observations suggest that 5% lidocaine may be used safely and effectively for the purpose of prolonged analgesia in selected patients with intractable chronic pain syndromes.