Cryoanalgesia

Using cold temperatures to alleviate pain has a long-standing history in medicine. Hippocrates, the father of medicine, wrote about it thousands of years ago, explaining how snow could ease pain from injuries. In the 1800s, a surgeon general under Napoleon noticed that soldiers who had endured cold weather in Russia felt less pain during amputations. Around this time, topical anesthesia was also discovered in ether and ethyl chloride spray. Cryoanalgesia, or cryoneuroablation or cryoneurolysis, is a specialized technique utilized in interventional pain management to achieve long-term pain relief. The origination of modern cryoanalgesia dates back to 1961 when Cooper et al introduced a device using liquid nitrogen within an insulated tube, capable of reaching a temperature as low as -196 °C. Cryoanalgesia gained prominence in 1976 when Lloyd et al published the first significant paper suggesting its superiority over alternative peripheral nerve destruction methods like alcohol neurolysis, phenol neurolysis, or surgical lesions. In this paper, Lloyd et al demonstrated a significant reduction in intractable pain for 52 of 64 patients treated with cryoanalgesia, including sciatic, intercostal, and facial nerve treatments. The median duration of pain relief was 11 days, with some patients having significant pain relief for up to 224 days. Cryoanalgesia involves the application of cold to tissues (approximately -70 °C) to ablate the targeted nerve, resulting in reversible neuronal injury to the peripheral sensory nerve. This induces a conduction block similar to local anesthetics. The intense cold temperature produces Wallerian degeneration, a reversible breakdown of the nerve axon, inhibiting the transmission of afferent and efferent signals. Because the nerve endoneurium, perineurium, and epineurium remain intact, the axon regenerates along the exoskeleton at approximately 1 to 2 mm/day. Once the axon has regenerated, it reconnects with the sensory receptor, and conduction starts again. Regrowth of axons into the perineurium eventually restores sensation, and the block functionally resolves. Thus, pain sensation may return over time (after weeks to months) and requires repeat administration. Repeating cryoanalgesia in the same anatomic location for subsequent surgical procedures does not result in adverse sequelae. Cryoanalgesia is an old technique with many possible future applications. Data for cryoanalgesia is encouraging for postoperative pain and in select groups for chronic pain. Clinical applications of cryoanalgesia encompass a wide range of conditions, including craniofacial pain (eg, trigeminal neuralgia, posterior auricular neuralgia, glossopharyngeal neuralgia), chest wall pain (eg, post-thoracotomy neuromas, rib fracture-related pain, post-herpetic neuralgia), abdominal and pelvic pain (eg, ilioinguinal, iliohypogastric, genitofemoral, subgastric neuralgia, pudendal neuralgia), low back and lower extremity pain (eg, lumbar facet joint pathology, pseudosciatica, intraspinous ligament or supragluteal nerve pain, sacroiliac joint pain, cluneal neuralgia, obturator neuritis, peripheral neuropathy), and upper extremity pain (eg, suprascapular neuritis, peripheral neuritis).