A condition in which the fingers or toes, or even larger portions of the limbs, become purple and bloated in appearance, and very painful. In people suffering from the condition – which is not a common one – the attacks come and go, being worse in summer (unlike chilblains), and worse on exertion or when the affected parts are warmed or allowed to hang down. The condition may appear without apparent cause, but is often associated with vascular diseases, such as HYPERTENSION and POLYCYTHAEMIA VERA. It also occurs in association with certain diseases of the central nervous system, and in cases of metallic poisoning (e.g. arsenic, mercury and thallium).