Efficacy of Lidocaine Patch in Relieving Severe Sickle Cell Leg Ulcer Pain
Authors: Lobo Clarisse Lopes de Castro , Queiroz Ana Maria Mach , De Matos Agueda Gloria Sabino , Thome Eleonora D'Avila , Ballas Samir K. 
Published: October 2019

Abstract
Introduction: Currently, there is a plethora of analgesics on the market that vary in type, method of application, duration of action, side effects and price. Thus we have, among other things, NSAIDs, opioids, anesthetics, cannabinoids, gases and venom-derived pain relievers. Formulations include short-acting, long-acting, extended release or controlled release. Administration of analgesia could be oral, topical, parenteral, intrathecal, epidural, rectal, intranasal, epidermal, submucosal, sublingual, etc. Despite the abundance of these drugs in the western world, there is an embarrassing dearth in developing countries. Thus the challenge to find the right analgesic for a specific patient with a specific etiology of pain is often overwhelming. It is within this framework of this complexity that we describe the efficacy of the lidocaine patch in a patient with a severely painful leg ulcer refractory to standard methods of therapy in a patient with sickle cell anemia (SS)
Patient & Methods: The patient is a 35 year-old African Brazilian man, known to have SS presented at the Instituto de Hematologia Arthur de Siqueira Cavalcanti (HEMORIO) in Rio de Janeiro, Brazil with a severely painful leg ulcer over the lateral left malleolus of 11 years duration. Dimensions of the ulcer were: 10 cm long and 6 cm wide and covered with purulent exudate. The pain was constant and stabbing in nature with an intensity score of 10 over 10 on presentation. The pain was partially responsive to oral tramadol and he refused to take opioids. Given the large size of the ulcer and purulent exudate, application of topical opioids was not considered an appropriate option due a potentially barrier effect of the exudate. Accordingly decision was made to treat the pain with lidocaine patch applied peripherally around the ulcer. Direct application of the patch would stick to the ulcer bed thus limiting its analgesic effect and previous studies showed high blood flow in the immediate peri-ulcer area compared to distant unaffected skin. The lidocaine patch was applied daily as follows: The ulcer was first cleaned with warm normal saline and polihexamide, collagenase was applied to the ulcer bed and the lidocaine patch was applied on the skin on the periphery of the ulcer. The lidocaine patch had to be cut to fit the periphery of the ulcer. The patient was instructed to remove the patch 12 hours after its application. He was taught how to remove and reapply the bandage around the ulcer. Moreover, the patient was instructed to keep a written diary of the intensity of the leg ulcer pain one, six and 12 hours after the application of the patch.
Results: On the first day of treatment the intensity of the ulcer pain was 10 over 10 and he did not allow the nurse to apply the bandage because that made the pain much worse. One hour after the application of the lidocaine patch the pain score dropped to 3 over 10 and at 6 and 12 hours post application the pain score was zero. On the next day he presented to the wound center with a pain score of 4 over 10 and this time he allowed the nurse to remove and apply the bandage without complaints. After the daily application of the lidocaine patch he did not require oral tramadol to treat the ulcer pain.
Conclusion: The lidocaine patch seems to be an effective and save method to treat the pain of sickle cell leg ulcers. Moreover, it obviates the need of oral analgesics to treat the pain. Recent studies suggest that nonneuronal tissues, such as skin keratinocytes in particular, express several isoforms of Na+ channels and of the TRPV family of receptors. These findings suggest that skin may play an important role in the pathophysiology of pain. Thus the application of lidocaine to the periphery of the ulcer inhibits the transmission of painful stimuli directly in situ. A potential problem is that the patch is expensive.

Disclosures
No relevant conflicts of interest to declare.