A 50-year-old lady sprained her ankle 2 months back from which she made a steady recovery. 2 months after the injury she gradually developed severe pain in her right ankle with the significant limitation of ankle movement. Clinical examination reveals oedema and shiny skin. What is the likely diagnosis?
COMPLEX REGIONAL PAIN SYNDROME (ALGODYSTROPHY)

Sudeck, in 1900, described a condition characterized by painful osteoporosis of the hand. The same condition sometimes occurs after fractures of the extremities and for many years it was called Sudeck’s atrophy. It is now recognized that this advanced atrophic disorder is the late stage of a post-traumatic reflex sympathetic dystrophy (also known as algodystrophy), which is much more common than originally believed (Atkins, 2003) and that it may follow a relatively trivial injury. Because of continuing uncertainty about its nature, the term complex regional pain syndrome (CRPS) has been introduced. Two types of CRPS are recognized: 

TYPE 1

a reflex sympathetic dystrophy that develops after an injurious or noxious event. 

TYPE 2 

causalgia that develops after a nerve injury. The patient complains of continuous pain, often described as ‘burning’ in character. At first, there is local swelling, redness and warmth, as well as tenderness and moderate stiffness of the nearby joints. As the weeks go by the skin becomes pale and atrophic, movements are increasingly restricted and the patient may develop fixed deformities. X-rays characteristically show patchy rarefaction of the bone.
Fibromyalgia
Complex Regional pain syndrome Type I {CRPS I}
Complex Regional pain syndrome Type II {CRPS II}
Peripheral Neuropathy