Painful Scars as Pain Generators: A Narrative Review and Case Series of Intralesional Lidocaine Treatment

Introduction: Active scars can be defined as “pain generators”: the pain associated with them may have an important impact on the patient’s quality of life. During the healing process, several local and systemic neurochemical changes occur, leading to alterations at both the tissue and systemic levels, with changes in the central nervous system (CNS) implicated in the development of chronic pain. Clinically, the features that define a scar as a pathological one include increased firmness, increased tissue thickness, and increased reactivity of the skin after palpation. The therapeutic approach, therefore, includes both local treatments that interfere with structural changes in the scar tissue and systemic treatments. Materials and Methods: A critical review of the literature regarding the role of local anesthetics in the clinical management of painful scars has been conducted. The paper also reports a series of cases involving patients affected by painful scars who were successfully treated with local lidocaine injections. A series of five cases of adult patients with active painful scars of post-traumatic and post-surgical etiology were treated with intra-lesional infiltration of 0.5% lidocaine. When appropriate, we associated other techniques. Pain intensity has been assessed using the NRS scale before the start of treatment, at the end of treatment, and at the 3-month follow-up. Results and Discussion: Lidocaine infiltration has been associated with a reduction in pain in patients affected by painful scars, as it might reduce the expression of inflammatory mediators. It could also have a neuromodulatory effect by reducing pain signal transduction. Eventually, a key role is the inhibition of NGF binding to its TrkA receptor. In all patients, we observed a long-lasting reduction in pain symptoms, suggesting that changes had occurred in the tissue and in the peripheral nervous system, and a modulation of central nervous system connectivity had been detected. No complications occurred. Conclusions: Local treatment with intralesional infiltration with 0.5% lidocaine was associated with clinically meaningful reductions in pain intensity in patients with painful post-traumatic and post-surgical scars, maintaining the benefit on pain over time, with no complications.