10.6 Complex Regional Pain Syndrome

Question 1

A 59-year-old female who is otherwise fit and well comes to the
pain clinic with complaints of severe burning pain and intermittent swelling from
the right palm to the mid-forearm.

She gives a history of fall onto her right arm while at work about 6 months ago.

She feels very depressed, as she is unable to
continue work due to inability to use the affected arm.

On examination the right arm looked swollen and was tender to touch.

What is the definition of complex regional pain syndrome (CRPS)?

Answer 1

The diagnosis of CRPS by clinical assessment is a diagnosis of exclusion.
Diagnostic criteria for CRPS according to ‘Budapest criteria’ 2007:

1. • Patient has continuing pain which is disproportionate to the inciting event.
2. • Patient has at least one sign in two or more of the categories (see below).
3. • Patient reports at least one symptom in three or more of the categories
     (see below).
4. • No other diagnosis can better explain the signs and symptoms.

Question 2

Categories + Symptoms for CRPS

Answer 2

Categories

1. Sensory
   Allodynia (to light touch and/or temperature sensation and/or deep somatic
   pressure and/or joint movement) and/or hyperalgesia (to pinprick)
2. Vasomotor
   Temperature asymmetry (more than 1 degree) and/or skin colour changes
   and/or skin colour asymmetry
3. Sudomotor/oedema
   oedema and/or sweating changes and/or sweating asymmetry

.4 Motor/trophic
Decreased range of motion and/or motor dysfunction (weakness, tremor,
dystonia) and/or trophic changes (hair/nail/skin)

Question 3

What is allodynia?

Answer 3

Allodynia is pain due to a stimulus that does not normally provoke pain.

Question 4

What is hyperalgesia?

Answer 4

Hyperalgesia is an increased response to a stimulus that is normally painful

Question 5

What are the differences between
CRPS I + II

Answer 5

Type 1
* Formerly known as reflex sympathetic dystrophy/ Sudek’s atrophy.

• Associated with injury to tissue
  (e.g. bones, joints, connective tissue but not necessarily to nerves).
• Trauma may be relatively trivial,
  most commonly precipitated by an
  orthopaedic injury to distal extremity
  (e.g. lower leg or wrist).

Type 2
* Formerly known as ‘causalgia’.

• Characterised with actual significant nerve injury without transection.
• More commonly associated with
  proximal nerves in upper leg and upper limb.
• Most frequently affected areas are
  sciatic, tibial, median, and ulnar nerves.

Question 6

What are the treatment options for CRPS?

Answer 6

1. Multidisciplinary approach
2. Engagement
3. Medical management
4. Psychosocial and behavioural management
5. Physical management
6. Regional Techniques
7. Surgical Techniques

Question 7

Engagement

Answer 7

• Education and information for the patient and their family

Question 8

Medical management

Answer 8

• Simple analgesia (e.g. paracetamol, NSAIDS)
• Opioids
• Antidepressants, anticonvulsants
• Free radical scavengers (e.g. vitamin C, intravenous N-acetylcysteine)

Question 9

Psychosocial and behavioural management

Answer 9

• Cognitive behavioural therapy
• Psychotherapy

Question 10

Physical management

Answer 10

• Physiotherapy
• TENS machine: noninvasive neuromodulation
• Functional restoration

Question 11

Regional techniques

Answer 11

• Intrathecal drug administration (e.g. opioids, clonidine)
• Preemptive regional anaesthesia preoperatively
• Regional nerve blockade (e.g. brachial or lumbar plexus block)
• Sympathetic blockade including intravenous local anaesthetics
  (Bier’s block),
  Stellate ganglion block

Question 12

Surgical techniques

Answer 12

• Thoracic or lumbar sympathectomy
• Spinal cord stimulation:
  implanted epidural electrode system
  (invasive neuromodulation).

Low-frequency pulsed stimulation appears to be a successful method.

• Limb amputation as last resort for irreversible infection or ischaemia

Question 13

Other proposed treatments

Answer 13

• NMDA antagonists:
  ketamine at low dose subcutaneously or infusion
• Capsaicin:
  topical capsaicin depletes peptide
  neurotransmitters from
  primary afferent pain pathways
• Glucocorticoids:
  may help with acute inflammatory stages of disease process
• Calcium-modulating drugs:
  calcitonin and bisphosphonates (both reduce
  bone resorption) help reduce symptoms in early CRPS
• One trial shows low dose intravenous immunoglobulin reduced pain
  intensity in a small group of patients who did not respond well to other
  treatments. A larger study involving individuals with acute phase of CRPS
  is underway.
• Hyperbaric oxygen: proposed benefit is a reduction in swelling and pain
  and improved range of motion

Question 14

Pathophysiology:

Answer 14

this remains incompletely understood,

but it has both peripheral and central components.

A chronic peripheral inflammatory process is suggested by
elevated local levels of inflammatory markers
(interleukin-8 and tumour necrosis factor-α)

suppression of some anti-inflammatory mediators (cytokines IL-4 and IL-10).

There are, in addition, alterations of central afferent processing, such as ‘wind-up’, with the
persistent perception of non-noxious afferent inputs as painful.

The pain may also
be maintained by efferent noradrenergic sympathetic activity as well as by circulating
catecholamines, although the lack of any significant response to sympathetic
blockade suggests that this is of lesser importance

α2-adrenoceptors
in local axons may be responsible for sudomotor dysfunction