1. Complex Regional Pain Syndrome
Dr. Dawood Nasir

2. Definition
CRPS: Complex regional Pain Syndrome, a neuropathic pain syndrome associated with sympathetic nervous system dysfunction
CRPS1: Previously known as Reflex sympathetic dystrophy, is a syndrome occurring after minor trauma
CRPS 11: Causalgia, usually occurs after major nerve injury

3. Complex Regional Pain Syndrome

4. Pathophysiology Peripheral & Central Mechanism Proposed mech include
Sensitization of small diameter polymodal C & A delta afferent fibers
Sensitization of central wide dynamic range neurons
Altered activity of low threshold A beta fibers

5. Question
Complex regional pain syndrome type 11 (Causalgia) is differentiated from complex regional pain synd type 1 by knowledge of
Etiology
Chronicity
Affected body region
Type of symptoms
Rapidity of onset

6. Answer (A)
Complex regional pain syndrome type 1 is a clinical syndrome of continuous burning pain usually occurring after an injury or surgery. Pts present with variable sensory, motor, autonomic, & trophic changes. Complex regional pain syndrome type 11 exhibits the same features as complex regional pain syndrome type 1, but the etiology is damage to a major nerve.

7. Epidemiology Incidence Unknown Prevalence
Women predominate (60-80 percent)
Mean age: years
Genetics
- Genetic correlation debated

8. Diagnostic criteria
At least 4 of the following must be present to diagnose CRPS
Examination findings:
Temperature / Color change.
Edema
Trophic skin, hair, nail growth abnormalities.
Impaired motor function.
Hyperpathia / Allodynia
Sudomotor changes

9. Diagnostic criteria-cont-
Diagnostic test results
Three phase bone scan that is abnormal in pattern characteristic.
This test is not needed if 4 or more of examination findings are present.

10. Stages of Complex regional type 1
CRPS 1 is divided into 3 stages
Acute
Dystrophic
Atrophic

11. Acute phase Pain: Localized, Severe, Burning
Extremity : Warm, swollen, nail growth
Skin: Dry & red, growth of hairs
X-ray: Normal
Mech.: Could be due to increase blood supply

12. Dystrophic Phase Pain: Diffuse, throbbing
Extremity: Cold, Cyanotic, edematous, muscle wasting.
Skin: Sweaty, thinning or loss of hairs
X-ray: Reveals osteoporosis
Mech.: Could be due to vasoconstriction

13. Atrophic Phase Pain: Less severe, may involve other extremities
Extremity: Severe muscle atrophy, contractures
Skin: Glossy & atrophic
X-ray: Reveals severe osteoporosis, & ankylosis of joints.
Mech.: Could be due to disuse atrophy

14. Physical Exam Allodynia: Perception of non noxious stimulus as painful
Hyperesthesia: Increased response to mild stimulus
Skin discoloration/mottling
Dry glossy extremity
Sweating
Edema
Abnormal temperature
Weakness, tremor, Hyperkeratosis, Brittle nail

15. Question Allodynia is defined as
Spontaneous pain in an area or region that is anesthetic
Pain initiated or caused by a primary lesion or dysfunction in the nervous system.
An unpleasant abnormal sensation, whether spontaneous or provoked
An increased response to a stimulus that is normally painful
Pain caused by a stimulus that does not normally provoke pain.

16. Answer (E). The IASP has defined several pain terms.
Anesthesia dolorosa: refers to spontaneous pain in an area or region that is anesthetic.
Neuropathic pain: is caused by dysfuction in NS.
Dysthesia :is unpleasant abnormal sensation.
Hyperalgesia :is increased response to painful stimulus.
Allodynia: is pain caused by a stimulus that does not normally provoke pain.

17. Tests Imaging Osteoporosis or fine demineralization on xray
Increased periarticular uptake in delayed bone scintigraphy

18. Pathological findings
Reduced thermoregulatory reflexes
Changes in sudomotor neuron activity
Neurogenic inflammation

19. Question
Which of the following choices is not consistent with a limb affected by complex regional pain syndrome?
Osteoporosis.
Allodynia.
Dermatomal distribution of pain
Atrophy of the involved extremity.
Hyperesthesia.

20. Answer ©
CRPS are associated with trauma. The main feature is burning & continuous pain ie exacerbated by normal movement, cutaneous stimulation, or stress usually weeks after the injury. The pain is not anatomically distributed.
Other associated features include cool, red, clammy skin & hair loss in the involved extremity. Chronic cases may be associated with atrophy & osteoporosis.

21. Differential Diagnosis
Infection
Hypertrophic scar
Bone fragments
Neuroma
Radiculopathy
Joint contracture
CNS tumor
Syringomylia

22. Medications First line Anticonvulsants
Gabapentin up to 900 mgs PO q8 hrs.
Pregabalin up to 300 mg PO q 12 hrs
Tricyclic antidepressants:
Amitriptiline up to 150 mgs PO qhs
Nortriptylene: upto 150 mgs PO qhs
Desipramine: upto 150 mgs PO qhs
- NSAIDs: If no complications

23. Second Line Other anticonvulsants Oxcarbazepine upto 600 mg PO q12 hrs
Lamotrigine upto 150 mgs PO qhs
Short & long acting opioids (Controversial)
Alpha adrenergic blocking agents
Corticosteroids(Short term only)
Biphosphonates
Topical therapies

24. Interventional Regional anesthetic approaches
Sympathetic blockade (local with or without steroids)
Peripheral nerve blockade
IV regional analgesia (reserpine, guanethidine, bretylium)
Chemical sympathetic neurolysis
Radiofrequency sympathetic rhizotomy
Epidural clonidine
Spinal cord stimulation

25. Rehabilitation Avoid immobilization Desensitization Mobilization
Edema control
Isometric/Isotonic strengthing
Stress loading/range of motion
Aerobic conditioning
TENS

26. Mental Test/Behavioral
Psychometric testing
Counseling
Behavioral modification
Relaxation therapy
Group therapy
Self-hypnosis
Psychotherapy
Medical management of depression

27. Technique for Stellate ganglion Block
Pt. supine, head midline, mouth slightly open
2 finger breadth or 2 cm. above clavicular head, trachea, sternocleidomastoid ms, & carotid sheath palpated at level of cricoid cartilage
2 fingers press down at lat. Edge of transverse process of C6, pushing the contents of carotid sheath laterally
A in. 23 or 25 gauge B bevel needle is inserted lat to trachea after skin inf. With local anesth.
Transverse of C6 encountered between 2 fingers withdraw needle 2 mm & inj 8-10 ml local

28. Stallate Ganglion

29. Stellate Ganglion Block

30. Question Stellate ganglion lies in closest proximity to
Common carotid artery.
Internal carotid artery.
Vertebral artery.
Axillary artery.
Aorta.

31. Answer ©
The stellate ganglion usually lies in front of the neck of the 1st rib. The vertebral artery lies anterior to the ganglion as it has just originated from the subclavian artery. After passing over the ganglion, it enters the vertebral foramen & lies posterior to the anterior tubercle of C6.

32. Signs of successful block
Horner’s synd.
Ipsilateral nasal congestion
Flushing of conjunctiva & skin
Temperature increase in the ipsilateral arm & hand

33. Side effects & complications
Lump sensation in throat
Hoarseness & dysphagia due to recurrent n block
Hematoma, osteitis
Brachial Plexus block
Phrenic nerve block
Epidural & subarachnoid block
Pneumothorax
Vertebral art. Inj. Causing loss of consciousness
Cardioaccelarator nerve block with hypotension

34. Follow up Prognosis Some resolve with minimal management
Most respond to initial conservative measure
Early aggressive treatment in those with rapid temporal changes has best results if initiated within 12 weeks of onset
Prognosis poor if pain becomes chronic with marked disability, thus emphasizing multidisciplinary approach.