Complex regional pain syndrome

The colour or temperature of affected areas may be different from the unaffected parts. These changes often vary a great deal, sometimes during the course of a day. For example, a hand or a foot could initially be warmer than expected, but later it becomes colder. Similarly, the affected area could be more red or blue than normal – or may become mottled in appearance.

Some people with CRPS become depressed, and others have negative feelings towards the affected limb.

Certain factors seem to trigger the development of CRPS – for example, sustaining a fracture or other injury, or having multiple limb operations. While the vast majority of people recover from these injuries without any complications, others go on to develop CRPS. There are also cases where CRPS develops without an injury or other obvious trigger.

It’s thought that a group of special nerve fibres called the sympathetic nervous system is involved in the development of CRPS. This system has several functions including the regulation of blood flow and skin temperature, and doctors have found that blocking the action of the sympathetic nervous system can be helpful in some people with early CRPS.

It’s also thought that communication pathways between the affected limb and the brain are disrupted so that pain continues long after the injury has healed.

What tests are there?

• An x-ray or scan of the affected limb may show thinning of the bone (osteoporosis) or other bone abnormalities.
• Blood tests may help to exclude other causes of pain and swelling.
• Blocking the sympathetic nervous system with a local anaesthetic is occasionally used as a diagnostic test. If this block eases the pain, then it’s likely that the sympathetic nervous system is either causing or contributing to the pain.

Drugs

There is no single drug treatment that works for everyone with CRPS but medications can be useful:

• Painkillers such as paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs) can be helpful, but your doctor may recommend codeine or tramadol if standard painkillers are not strong enough.
• Morphine and similar medications (for example, oxycodone or buprenorphine) may be used for very severe pain.
• Neuromodulatory drugs such as gabapentin and pregabalin can help by reducing pain signals from the nerves to the brain.
• Antidepressants such as amitriptyline and duloxetine can also reduce pain signals to the brain.
• Bisphosphonates, which can be given as tablets or injections, seem to help in some cases although the reasons for this aren’t fully understood.
• Capsaicin, a cream made from chilli peppers, relieves pain although  causes a burning sensation for the first few days so it might not be suitable if a large area or a whole limb is affected.

Sympathetic blocks

If you benefit from a diagnostic sympathetic block, then further blocks may occasionally be recommended. Blocks of the sympathetic nervous system can be either temporary or permanent.

• Temporary sympathetic blocks – Temporary blocking of the sympathetic nervous system can be carried out using either local anaesthetic or guanethidine (a drug sometimes used for hypertension), both of which are given by injection.
  • Local anaesthetic blocks – Local anaesthetic is injected around the sympathetic nerves. If CRPS affects the upper limb (hand or wrist), then the injection is made into the side of the neck. If CRPS affects the lower limb (foot, ankle or knee), then the injection is made into the flank (the side). If the block is successful, then its effect will be apparent within a few minutes.
  • Guanethidine blocks – A tourniquet is applied to the limb and guanethidine is injected into a vein. This suppresses the sympathetic nervous system. Guanethidine blocks are only rarely used.

If the temporary block helps, further blocks may be given from time to time. Alternatively the doctor may recommend a permanent block.

• Permanent sympathetic blocks – A permanent block of the sympathetic nervous system may be performed either surgically or by injection.

Rehabilitation therapies

Physiotherapy and occupational therapy are recommended for most people with CRPS, and are very important both for relieving pain and keeping the affected limb mobile. The therapies used will depend on how long you have had CRPS, but will probably include:

• exercises to restore strength and function in the affected limb
• pain relief therapies such as transcutaneous electrical nerve stimulation (TENS)
• desensitization – this is a technique that aims to normalize touch sensations in the affected limb. It involves touching the skin frequently with different-textured fabrics and other substances – for example, wool, silk, cotton wool – gradually working towards the painful areas.
• relaxation and/or stress management techniques
• body perception awareness – this can be especially helpful for people who develop negative feelings about the affected limb. It encourages people to look at, touch, and think about the affected limb as often as possible.

Other treatments

Early research suggests that mirror visual feedback therapy (mirror therapy) may be helpful for some people with early CRPS, although the technique hasn’t yet been widely used. Exercises are performed with the aid of a mirror positioned so that the patient sees a reflection of the unaffected limb while the affected limb is hidden from view.

Exercise

It’s very important to follow a programme of exercises to maintain mobility and function in the affected limb. It’s best to get advice initially from a physiotherapist who can develop a programme of exercises tailored to your needs.

Read more for general advice and specific exercises that will help you keep active.

Stress management and relaxation

Coping techniques including stress management and relaxation classes can be very helpful in managing complex regional pain syndrome on a day-to-day basis.