Treatment of localized post-traumatic neuropathic pain in scars with 5% lidocaine medicated plaster

Gerardo Correa-Illanes¹, Wilfredo Calderón², Ricardo Roa³, José Luis Piñeros³, Jacqueline Dote⁴, David Medina<sup>4

1</sup>Servicio de Rehabilitación, Profesor Adjunto Universidad de Chile, ²Jefe Servicio Cirugía Plástica y Quemados, ³Servicio de Cirugía Plástica y Quemados, ⁴Servicio de Rehabilitación, Hospital del Trabajador de Santiago, Santiago, Chile

Objective: To evaluate the use of 5% lidocaine medicated plaster (LMP) for treating painful scars resulting from burns or skin degloving.

Patients and methods: This was a prospective, observational case series study in individuals with painful scars <70 cm² in area, caused by burns or skin degloving. The study included a structured questionnaire incorporating demographic variables, pain evaluation using the numeric rating scale (NRS), the DN4 questionnaire, and measurement of the painful surface area. Patients with open wounds in the painful skin or with severe psychiatric disease were excluded.

Results: Twenty-one men and eight women were studied, aged (mean ± standard deviation) 41.4 ± 11.0 years, with painful scars located in the upper extremity (n = 9), lower ­extremity (n = 19), or trunk (n = 1). Eleven patients (37.9%) had an associated peripheral nerve lesion. The scars were caused by burns (n = 13), degloving (n = 7), and/or orthopedic surgery (n = 9). The duration of pain before starting treatment with lidocaine plaster was 9.7 ± 10.0 (median 6) months. The initial NRS was 6.66 ± 1.84 points, average painful area 23.0 ± 18.6 (median 15) cm², and DN4 score 4.7 ± 2.3 points. The duration of treatment with LMP was 13.9 ± 10.2 (median 11) weeks. After treatment, the NRS was reduced by 58.2% ± 27.8% to 2.72 ± 1.65. The average painful area was reduced by 72.4% ± 24.7% to 6.5 ± 8.6 (median 5) cm². Nineteen patients (69%) showed functional improvement following treatment.

Conclusion: LMP was useful for treating painful scars with a neuropathic component, ­producing meaningful reductions in the intensity of pain and painful surface area. This is the first time that a decrease in the painful area has been demonstrated in neuropathic pain using topical therapy, and may reflect the disease-modifying potential of LMP.

Keywords: chronic postsurgical pain, chronic post-traumatic pain, lidocaine medicated plaster, neuropathic pain