Cryoanalgesia for refractory neuralgia

Introduction Neuropathic pain from peripheral nerve disease or injury consequent to trauma, surgery, infection, cancer or other causes is often referred to as neuralgia. It is common and often difficult to treat. For instance, the incidences of chronic post-surgical pain (CPSP) are reported to range between 25 to 50% in patients underwent thoracic surgeries[1,2] , mastectomies[3,4] or abdominal surgeries[5]. A significant number of patients with CPSP is accompanied with a neuropathic component[1,2]. Neuralgia is typically described by patients as burning or "electric-shock" pain sensation. In many patients, neuropathic pain is debilitating and interferes with many aspects of their lives and significantly degrades quality of life. It is often refractory to pharmacological therapy as well as surgical exploration and decompression[6,7]. Targeted nerve blocks usually provide short-term pain relief. With positive responses to nerve blocks, clinicians often consider neuromodulatory or neurodestructive therapies for longer term pain relief. Neuromodulation is typically achieved by peripheral nerve stimulation, spinal cord stimulation, cortical stimulation, or deep brain stimulation[8]. Neurodestruction can be achieved by controlled thermal lesion using radiofrequency ablation or by cryoneurolysis[9,10]. Cryoneurolysis, the use of cold to provide anesthesia or analgesia, is the oldest anesthetic and analgesic technique that is still in current clinical use. Hippocrates (460-377 BC) has been credited with providing the first written record of the use of ice and snow packs as a local preoperative analgesic technique[11]. In 1962 Irvine Cooper et al. constructed the first cryoprobe used for cryoanalgesia[12]. It was based on the phase change of liquid nitrogen to produce temperatures of -196oC. In 1967, Amoils developed a less complex hand held unit that used either carbon dioxide (CO2) Abstract