RSD is a very difficult problem that is now called algodystrophy.
(Other names include Sudeck atrophy and shoulder hand syndrome)

It is characterised by several stages in its development and manifestations.

It often develops after trauma to a peripheral limb in 50 % of cases and 25 % after stroke / heart attack / nerve injury and 25% are of unknown cause.

The condition is characterised by unrelenting pain-which is a deep aching /burning character, and is severely tender, such that the patient overprotects the limb and avoids any movement. The condition also is occasionally seen in children.
I see about 5 per year in my practice. The clinical finding is a diffusely tender limb / extremity, with a tendency to temperature changes and sweating of the limb compared to the other side.

Stage 1 (Steinbroker classification - pain tender swelling, flushing sweating of the limb..this may persist for 3 - 6 months.

Stage 2 - Changes are seen to the skin - shiny and atrophied / thinned. Lasts 3-6 months.
Stage 3 - atrophy of the limb and skin with contractors.

No one really knows what causes it, but it is felt to be an overactivity of the sympathetic nervous system pathways.

The best tests for it if x rays don’t show patchy or diffuse osteopenia of the underlying bones, is a technetium bone scan with blood flow studies.

A scan shows fairly characteristic changes.

Blood tests are usually completely normal.

Therapy is difficult.
1. Aggressive physiotherapy despite the pain..with active mobilisation to prevent progression to stage 2 or 3.
2. Medications - analgesia and anti inflammatories , are in my opinion poorly responsive except in the early stages.
3. Corticosteroids are controversial- I don’t use them for this.
4. Local cortisone injections for regional tendonitis problems are potentially useful
5. I have found the best results from beta blockers - Inderal (or propranolol) in small doses 20mg bd. increasing depending on response to 80mg po tds. The medication is usually required for several months as physiotherapy proceeds.
6. For resistant cases...Calcitonin injections 100iu given as subcutaneous injections 5 days per week for one week the 3 days per week for 2 weeks then as required. This however is expensive and I only use if Inderal doesn’t work.
7 Other therapies include intravenous guanethidine and even regional sympathetic nervous system blocks.

I have never yet had a treatment failure that required the latter surgical option -
which itself is controversial and not fully or universally effective