The efficacy of liquid nitrogen spray cryotherapy for the relief of pain during steroid injection used to treat keloids and hypertrophic scars
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Abstract
BACKGROUND: Keloids and hypertrophic scars arise from excessive skin repair after injury or inflammation and can impact patients’ physical and psychological well-being. Intralesional corticosteroid injection is an effective treatment but requires multiple sessions and can be painful. Consequently, several methods have been explored to reduce injection-related pain, although no single approach has been universally accepted as the best option.
OBJECTIVE: To evaluate the efficacy of liquid nitrogen cryospray application prior to corticosteroid injection in reducing pain during intralesional corticosteroid treatment for keloids and hypertrophic scars.
METHODS: This randomized cross-over study included 40 participants diagnosed with keloids or hypertrophic scars at Pranangklao Hospital between February and July 2025. The participants were divided into two groups of 20. Each participant received two intralesional corticosteroid injections at a single lesion, spaced 4–5 weeks apart. In one of the sessions, cryospray with liquid nitrogen was applied prior to injection, randomized to occur in either the first or second session. Pain was assessed using the Visual Analogue Scale (VAS) at three timepoints: during needle insertion, during drug administration, and 30 minutes post-injection. Adverse events were recorded, and overall patient satisfaction was assessed after the completion of both treatments.
RESULTS: 39 patients completed the study. Pain scores during both needle insertion and drug administration were significantly lower in the cryospray-treated sessions compared to non-cryospray sessions (p<0.001). However, no significant difference was observed 30 minutes post-injection (p=0.058). Patient satisfaction was significantly higher in the cryospray group (p<0.001). Reported adverse effects were mild—such as itching, minor burning sensation, and bruising—with no significant difference in incidence between the two treatment methods.
CONCLUSIONS AND RECOMMENDATIONS: Cryospray with liquid nitrogen prior to corticosteroid injection significantly reduces procedural pain and improves patient satisfaction without causing serious adverse effects. This method is safe, time-efficient, cost-effective, and easily applicable in general clinical practice using existing equipment.
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