Cryoanalgesia. The application of low temperatures to nerves to produce anaesthesia or analgesia.

The introduction of cryoanalgesia has reawakened interest in the therapeutic use of cold as a means of producing pain relief. The historical background to both local cooling and nerve freezing is recorded and the advances since the introduction of cryoprobes in 1961 are described. The possible mechanisms of freeze damage, the physical changes occurring in tissues as a result of ice crystal formation and the influence of the probe design on the size of individual cryolesions are all discussed. Gas expansion cryoprobes are described and the application of nerve freezing in the control of both post operative and chronic pain reported.