Decompression sickness (DCI) can present itself in many different guises, with symptoms varying from slight mottling of the skin or subcutaneous rash to full neurological symptoms. While the latter is necessarily thought of as a serious health problem, the former is often dismissed as "only a skin bend." Forget the "only."
A skin bend most often manifests itself as mottling on the upper torso, upper arms, and buttocks in varying degrees of severity. There is no generally accepted explanation of how gas coming out of solution is related to these skin changes, but explanations include 1) the occurrence of gas bubbles in subcutaneous tissues; 2) the obstruction of subcutaneous arteries with bubbles bypassing the lungs (as with PFO -- patent foramen ovale); 3) an inflammatory reaction to bubbles presenting locally in the tissues; or 4) bubbles causing injury to the interior surface of blood vessels at remote locations.
Recently a Dutch research team has presented a novel hypothesis that links these skin changes to subclinical brain changes caused by a cerebral arterial gas embolism (AGE). After experiments with anesthetized pigs, they hypothesized that the skin mottling might be the result of brain lesions caused by gas bubbles.
While this is still only a hypothesis, DAN, on it's the divelab web page, thinks it's worth considering the practical implications. DAN injury data analysis indicates that at least one-fifth of divers with skin bends also have neurological symptoms.
The upshot is that any diver exhibiting symptoms of a skin bend should also be evaluated neurologically. Repeated episodes of skin bends, although seemingly innocuous, should be taken as a possible indicator of a subclinical brain injury. Don't dismiss it. Take it seriously.
(Source: DAN/Kemper - Diving Hyperbaric Medicine.)