Methods for Treating Port Wine Stain Birth Marks, Hemangiomas and Other Conditions Caused By Aberrant Blood Vessels
Background: Cutaneous vascular lesions including port wine stains (PWS) and hemangiomas are frequently treated with laser and light devices. The pulsed dye laser (PDL) is the current standard means of treatment care for PWS and achieves effect by selectively targeting tissue vasculature. However, few PWS patients (< 20%) achieve complete blanching of their lesion and multiple treatments (5 -30 or more) are generally required. One primary factor limiting vascular lesion blanching for many patients, is the limited ability of the PDL to remove all targeted vessels, especially those which are small and superficial and may contribute significantly to the clinical appearance of the lesion. Technology: The present invention provides methods for treating port wine stain birthmarks, hemangiomas, and other lesions wherein aberrant blood vessels are present. A photosensitizing agent is administered to the patient. Thereafter, light energy (e.g., laser energy) is applied to the affected area of skin. Some of the light energy interacts with the photosensitizing agent and causes damage to the aberrant blood vessels. As a result, the irradiation may cause photocoagulation of the aberrant blood vessels, while the light energy (depending on variables such as wavelength and intensity) remains sufficiently low to avoid the occurrence of clinically significant scarring or other thermal damage to the skin or surrounding tissues.
In some applications of the invention, a two-staged irradiation treatment may be applied following administration of the photosensitizing agent. In the first stage of the irradiation treatment, sub-therapeutic irradiation (e.g., a continuous wave argon pumped-dye laser or a diode laser) is applied to activate the photosensitizing agent and to cause some of the aberrant blood vessels to become weakened or damaged. The first stage of the irradiation causes a photochemical effect on the aberrant blood vessels. In the second stage of the irradiation treatment, pulsed laser energy is applied to the lesion, thereby causing complete or near complete photocoagulation of the aberrant blood vessels and resultant blanching of the lesion. Thus, this second stage of the irradiation procedure causes a photothermal effect on the weakened blood vessels. In some applications of the invention wherein the two-staged irradiation is used, it may be possible to forego administration of a photosensitizing agent. Application: The present invention is likely to be particularly useful for treatment of PWS and hemangiomas. It should be noted that the wavelength of light delivered during this first stage of the irradiation procedure may be selected to define the desired penetration depth. Thus, with proper selection of light parameters, other vascular lesions including pyogenic granulomas, telangiectasia and malignant vascular tumors may also be amenable to treatment by this modality
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