According to Healthline.com, the most apparent indication of a potential SWS is a port-wine stain on one side of the face, but it may or may not indicate SWS. However, all children with a diagnosis of SWS do tend to have a port-wine stain. The red discoloration is due to dilated blood vessels that make the skin appear reddened. A diagnosis of SWS, typically requires a port-wine stain, plus abnormal blood vessels on the same side of the brain as the stain. In some, abnormal blood vessels do not seem to trigger symptoms, while in others, symptoms may include weakness on one side of the body, increased eye pressure that can lead to glaucoma, cognitive impairment, developmental delays, and even seizures and/or paralysis.