Nerve Pain after Burn Injury: A Proposed Etiology-Based Classification

Background: Understanding the mechanism of nerve injury may facilitate managing burn-related nerve pain. This proposed classification, based on cause of nerve injury, was developed to enhance the understanding and management of burn-related nerve pain. Methods: This retrospective investigation included patients aged 15 years or older admitted to the burn center from 2014 to 2019. Burn-related nerve pain was patient-reported and clinically assessed as pain 6 months or more after burn injury, unrelated to preexisting illnesses/medications. The pain classification consisted of direct nerve injury, nerve compression, electrical injury, and nerve dysfunction secondary to systemic injury. The four categories were statistically analyzed between groups, using 52 variables. Results: Of the 1880 consecutive burn patients, 113 developed burn-related nerve pain and were eligible for validation of the classification: direct nerve injury, n = 47; nerve compression, n = 12; electrical injury, n = 7; and nerve dysfunction secondary to systemic injury, n = 47. Factors, significantly increased, that distinguished one category from another were as follows: for direct nerve injury, continuous symptoms (p < 0.001), refractory nerve release response (p < 0.001), nerve repair (p < 0.001), and pruritus (p < 0.001); for nerve compression, Tinel signs (p < 0.001), shooting pain (p < 0.001), numbness (p = 0.003), intermittent symptoms (p < 0.001), increased percentage total body surface area burned (p = 0.019), surgical procedures (p < 0.001), and nerve release (p < 0.001); and for electrical injury, Tinel sign (p < 0.001), intermittent symptoms (p = 0.002), amputations (p = 0.002), fasciotomies (p < 0.001), and nerve release (p < 0.001). Nerve dysfunction secondary to systemic injury was distinguished by significantly less Tinel signs (p < 0.001), shooting pain (p < 0.001), numbness and tingling (p < 0.001), pruritus (p < 0.001), fascial excision (p = 0.004), skin grafts (p < 0.001), amputation (p = 0.004), nerve releases (p < 0.001), and third-degree burns (p = 0.002). Conclusion: A classification consisting of direct nerve injury, nerve compression, electrical injury, and nerve dysfunction secondary to systemic injury is presented that may guide patient management and research methods, with the goal of improving pain outcomes in burn-related nerve pain.