Purpura Formation a Poor Clinical Endpoint for Laser Treatment

How effective are subjective clinical endpoints in determining the effectiveness of laser therapy in the treatment of capillary malformations, also commonly referred to as port wine stains (PWS)?

Background: PWS arise from ectatic blood vessels in the dermis. Various lasers are used to selectively photocoagulate these aberrant blood vessels. Purpura formation is commonly used to assess the extent of photocoagulation. This paper explores other methods used to assess the extent of photocoagulation during laser therapy.

Study design: Prospective cohort study

Setting: Beckman Laser Institute and Medical Clinic, University of California, Irvine, and the Scripps Clinic Laser and Cosmetic Dermatology Center, San Diego

Synopsis: A clinic-friendly laser speckle imaging (LSI) instrument was developed and used to provide real-time images of blood flow during laser therapy for PWS. Various lasers were used to treat these subjects, including the modified V-beam, V-beam, Cynergy and alexandrite. A total of 22 subjects (13 female, nine male) with facial PWS were enrolled in the study. Speckle image data were collected both before and about 40 minutes after laser therapy.

Results of these studies demonstrated a poor correlation between purpura formation and the extent of photocoagulation. There was a mean perfusion reduction of at least 20 percent in the majority of patients after a single treatment. In a significant number of patients, there was a heterogeneous response of the PWS to laser treatment. A period of about 30 minutes is required after laser treatment for the overall acute effects of therapy to be adequately assessed.

Bottom line: Purpura formation is a poor clinical endpoint to judge the efficacy of photocoagulation during laser treatment of PWS.

Citation: Huang YC, Tran N, Shumaker PR, et al. Blood flow dynamics after laser therapy of port wine stain birthmarks. Lasers Surg Med. 2009;41(8):563-571.

—Reviewed by Ravindhra G. Elluru, MD, PhD