High-concentration tetracaine for the management of trigeminal neuralgia: quantitative assessment of sensory function after peripheral nerve block.

OBJECTIVE: This study examined the effects of peripheral nerve block with high-concentration tetracaine for the management of trigeminal neuralgia, and evaluated sensory function by measuring the postblock current perception threshold. METHODS: Five infraorbital nerve blocks were performed in five elderly patients using 4% tetracaine dissolved in saline or 0.5% bupivacaine. The authors used a neurometer to compare postblock current perception threshold between the block side and the contralateral healthy side, and used cold tests to assess the sensory level. RESULTS: The analgesic effect of tetracaine blocks continued for a median period of 2 months (range, 1.5-months). Hypesthesia was observed in all patients after the block but resolved within a mean period of 2.2 weeks. Although differences in current perception threshold values between sides were not significant in any patient, block-side values in two patients were clinically higher than contralateral-side values (250 vs. 5 Hz) for some time before returning to normal levels. CONCLUSION: Peripheral nerve block with high-concentration tetracaine is a relatively safe and useful technique in the management of trigeminal neuralgia, particularly among older patients and those with systemic problems.