COMPLEX REGIONAL PAIN SYNDROME

– Dr. Sunita Lawange
CONSULTANT PAIN PHYSICIAN

DEFINITION: A variety of painful conditions which occur after
the injury with regional distribution having a distal predominance of abnormal findings,
which exceed in intensity and duration of expected clinical course of the inciting
event.

Complex regional pain syndrome (CRPS) comprises of variety of
clinical presentations in which severe pain is associated with vasomotor changes
and dysfunction in response to the injury. It was earlier named as causalgia, reflex
sympathetic dystrophy (RSD). The term CRPS was coined by Robley Dunglison from the
Greek words for heat and for pain in a special consensus workshop at Florida in
1999. The International Association for the Study of Pain (IASP) changed the name
of reflex sympathetic dystrophy to CRPS I and causalgia to CRPS II, because not
all pain in this spectrum are sympathetically maintained.

INCIDENCE

The highest incidence of CRPS is between 50-70 years , though it can occur at
any age with higher incidence in females F: M= 3-4: 1 Incidence in upper limb is
60% and in lower limb about 40%CRPS is a diagnosis seen with increasing frequency
in injured workers but it can occur after surgery or any vascular event.

PRECIPITATING FACTORS

Trauma
Post-surgical factors
Neurologic injury
Carcinoma
Burns

IASP Diagnostic Criteria for CRPS (1994)

The presence of an initiating noxious event
Continous pain, allodynia or hyperalgesia
edema, changes in skin blood flow or abnormal sudomotor activity in the
region of pain.

Modified IASP research diagnostic criteria for CRPS: Budapest Criteria

Continuous pain disproportionate to the inciting event.
Must report at least one of the following symptom in each of the four following
categories:
1. sensory: reports of hyperesthesia/ allodynia
2. Vasomotor: temperature asymmetry/skin colour changes/ skin colour asymmetry
  in the affected region.
3. Sudomotor/ Edema: edema and / or sweating changes/asymmetry in the affected
  region.
4. Motor/ trophic: decreased ROM/ motor dysfunction and / trophic changes
  {hair, nail. Skin}
must have at least one sign at the time of evaluation in two or more categories:
1. Sensory: evidence of hyperalgesia and or allodynia to light touch/deep
  pressure and /or joint movement.
2. Vasomotor: evidence of temperature asymmetry and / or skin colour changes
  and / or symmetry.
3. Sudomotor/ edema: evidence of edema and /or sweating changes and / sweating
  asymmetry.
4. Motor/ Trophic: evidence of decreased range of motion and / or motor
  dysfunction and /or trophic changes.
There is no other diagnosis that better explains the signs and symptoms.

DIAGNOSIS

It purely remains a clinical one. Detailed medical history, Development, time, course, distribution and characteristic of pain, general neurological examination, detection of swelling, sweating, trophic, temperature and motor abnormality in the disturbed area is important. The diagnostic tools to confirm the diagnosis are:

Bone scintigraphy
Radiography
Quantitative sensory testing(QST)
Autonomic functions
Thermography
Sudomotor testing
All these investigations can be used to follow the progress of the
condition and the response to the treatment.

Stages of CRPS

Stage one: ACUTE

Edema
Severe burning pain, paresthesia
Muscle spasms
Joint stiffness
Restricted mobility
Rapid hair and nail growth
Increased sweating (hyperhidrosis)

Stage two: DYSTROPHIC

Intense pain
Swelling spreads
Hair growth diminishes
Nails become cracked, brittle, grooved, and spotty
Osteoporosis
Joints thicken
Muscles wasting

Stage Three: ATROPIC

Irreversible changes in the skin and bones
Pain may envolve entire limb
Marked muscle atropy
Severe restricted range of movement
Flexor tendon contracture
Marked bone softening and thinning

Pathophysiology of CRPS

Autonomic nervous system mediated
Inflammation
Autoimmune etiology
Central mechanism
Psychological factors
Role of HLA system
Complex disease of peripheral and central nervous system

MANAGEMENT OF CRPS

The targeted therapy in management of CRPS include:

Minimization of pain and distress
Restoration of function
Improvement of quality of life
Severity of disease determines the therapeutic regime. A
methodical patient approach to pharmacotherapy is essential in CRPS. The
various mechanisms targeted by the pharmacological agents are:
Inflammatory process: nsaids, corticosteroids, immunoglobulins. Monoclonal
antibodies such as anti TNF –alpha antibodies
Sensitization of pain: intrathecal baclofen, capsaicin, carbamazepine,
anticonulsants, NMDA receptor blocker, Sodium channel blocker, Opioids and
TCAs.
Sympatholytic agents: alpha 2 agonist, guanithedine
Free radical scavengers: DMSO, NAC, vitamin C
Bisphosphonates
Intranasal Calcitonin

INTERVENTIONAL PAIN TREATMENT ALGORITHM FOR CRPS

Minimally Invasive Therapies:

Sympathetic nerve blocks
Intravenous regional nerve blocks
Somatic nerve blocks

More invasive therapies:

Epidural and plexus blocks
Neuro-stimulation: SCS and PNS
Continuous intrathecal pump implantation

Surgical and Experimental Therapies:

Sympathectomy
Endoscopic thoracic sympathectomy
Motor cortex stimulation
Mirror therapy
Psychological interventions
Pulsed Radiofrequency Neurolysis

CONCLUSION

CRPS is a severe debilitating heterogeneous pain disorder that results in physical as well as emotional burden to the patients. It is associated with significant disability, anxiety and depression. The pathophysiology of CRPS is yet not fully known. The diagnosis of CRPS is purely clinical and the use of diagnostic tests has not been validated.

Management of CRPS needs a multimodal and multidisciplinary approach with the inclusion of medical, psychological, physical and rehabilitation interventions. The treatment should be aimed at remodulating, normalizing, disrupting or preventing the progression of abnormalities in pain processing. No single drug or drug combination works for these patients. Spinal cord stimulation, neuraxial route of analgesia, motor cortex stimulation are very promising modalities for managing patients with intractable CRPS. Overall these guidelines help but a holistic approach encompassing constant assurance, ongoing support, compassion and flexibility is essential for successful treatment of CRPS.

COMPLEX REGIONAL PAIN SYNDROME