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 in 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 which interferes with structural changes in the scar tissue and systemic treatments. Materials and Methods: A critical review of the literature regarding the role of local anaesthetics 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 aetiology, have been 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 3 months’ follow-up. Results and Discussion: Lidocaine infiltration has been demonstrated effective in the treatment of painful scars, as it reduces the expression of inflammatory mediators. It also has a neuromodulatory effect by reducing the pain signal transduction. Eventually, a key role is the inhibition of NGF binding to its TyrkA receptor. In all patients, we observed a long-lasting reduction in pain symptoms, suggesting that changes had occurred in the tissue, in the peripheral nervous system and a modulation of central nervous system connectivity had been detected. No complications occurred.