Cutaneous pain is a common symptom in clinic and available therapies are inadequate. We developed an injectable method of cryoneurolysis with ice slurry, which is neural selective and leads to long-lasting decrease in mechanical pain. The goal of this study is to determine if slurry injection treats cutaneous pain without inducing the side effects associated with conventional cryoneurolysis.
Using the rat sciatic nerve, we investigated effects of slurry on nerve structure and function in comparison to an FDA-approved cryoneurolysis device. Immunofluorescence staining and CARS microscopy were used to examine histological effects on the sciatic nerve and on downstream cutaneous nerve fibers. We used the CFA model of cutaneous pain to study the effect of the slurry on reducing pain.
Structural changes in myelin induced by slurry were comparable with conventional cryoneurolysis that uses much colder temperatures. The decrease in mechanical pain with slurry was less profound but lasted longer without dysesthesia. Slurry did not induce reduction of epidermal nerve fibers or change in thermal pain sensitivity. Slurry treated rats showed reduced cutaneous mechanical pain in response to CFA.
Slurry injection can be used to successfully reduce cutaneous pain without causing dysesthesia.