Peripheral nerve blocks are frequently used to treat chronic pain, but nerve block in itself may cause pain. Cooling the skin may inhibit pain associated with needle puncture to a venous, artery to the muscles, but it is not known if skin cooling inhibits pain associated with peripheral nerve block for chronic pain.

As a randomized crossover design, we studied 14 patients (after obtaining approval from the research ethics committee and written informed consent) in whom a supraorbital, infraorbital or jaw nerve block was indicated, to compare the degree of pain (assessed using the Numerical Rating Scale) during needle puncture and during injection of a local anesthetic (2 ml of 0.2% ropivacaine), with and without cooling of the skin (to 20 °C).

Pain was significantly less with skin cooling than without, during needle puncture (P = 0.002; 95%CI for median difference: 3–3), and during injection of a local anesthetic (P = 0.0036: 95%CI for median difference: 2–2). Injection of a local anesthetic was significantly more painful than needle puncture, both with skin cooling (P = 0.0039) and without skin cooling (P = 0.015). There was no significant difference in the effect of skin cooling in reducing pain between needle puncture and injection of a local anesthetic (P = 0.48).

In patients receiving peripheral nerve blocks to the face, cooling of the puncture site of the skin may effectively inhibit pain during needle puncture and during injection of a local anesthetic.

Clinical trial registration jRCT1031230725.