Chapter 47- Complex Regional Pain Syndrome Flashcards
(28 cards)
What is complex regional pain syndrome?
pain + sudomotor or vasomotor instability
Caused by
- Type I–> noxious stimuli
- Type II–> nerve injury
pain is out of proportion to inciting event
What are the 2 types of CRPS?
CRPS-I is triggered by noxious stimulus NOT in single nerve distribution
CRPS-II is triggered by nerve injury and is usually in the distribution of that nerve.
What is the diagnostic criteria for CRPS?
A) history of trauma to area with pain that is out of proportion to inciting event plus 1 of the following
- Abnormal function of the sympathetic nervous system
- swelling
- movement disorder
- changes in tissue growth (dystrophy and atrophy)
Describe the pain that typical of CRPS?
continuous burning type pain that is not limited to dermatomal pattern
Define allodynia
pain caused by a stimulus that normally does not provoke pain (light touch)
Define hyperalgesia
increased response to stimulus that is normally painful (increased response to pinprick)
Define hyperesthesia
increased sensitivity to a stimulus that is either due to a diminished threshold or increased response to stimuli that are normally recognized ==includes both allodynia and hyeralgesia
Define dysesthesia
An abnormal sensation that is unpleasant to patient, either spontaneous or evoked (lumbar radiculopathy)
What are the stages associated with CRPS?
Stage I
- onset of severe pain limited to site of injury
- hyperesthesia
- localized swelling
- stiffness and limited mobility of affected area
- skin is red, warm and dry
- lasts a few weeks
Stage II
- pain becomes more severe and more diffuse
- swelling spreads and may change to hard/brawny type
- hair and nail changes- course and scant hair, brittle nails
- osteoporosis of bones
- muscle wasting
Stage III
- marked wasting of tissue- irreversible
- pain is intractable and involves entire limb
What is the pathophysiology of the development of CRPS?
multiple hypothesis but all involve:
- abnormal discharges in sympathetic and nociceptive afferents after trauma
- sensitization of the peripheral sensory receptors after the sympathetic hyperactivity
- formation of artificial synapes after peripheral nerve injurery
- spontaneous neuronal ectopy at the site of demyelination
- central reorganization of pain processing like central sensitation
What receptor is often implicated in central pain sensitization?
NMDA receptor
What happens with central sensitization?
Injury results in lower threshold to fire pain transmission nuerons and increases in the receptive fields
What is sympathetically mediated pain?
(SMP) is pain that is maintained by sympathetic innervation or circulating catecholamine- describes a pain mechanism NOT a clinical syndrome
If a sympathetic block provides pain relief, it is SMP.
What is sympathic independent pain?
(SIP) is are pain conditions that show features of sympathic activity but DO NOT respond to sympathetic blocks.
How does CRPS differ from neuralgia?
Neuralgia is paroxsymal and follows the distribution of the nerve WITHOUT vasomotor or sudomotor changes
CRSP is sustained, diffuse, burning WITH vasomotor and/or sudomotor changes
How can you work up a patient that you think has CRPS?
You must rule out other things as CRPS is a diagnosis of exclusion. Can try tests such as:
- sweat test- excessive sweating is suggestive of CRPS
- xray imaging- osteoporosis limited to painful area is suggestive of CRPS
- positive diagnostic sympathetic blocks will confirm the sympathetically mediated portion of the CRPS
Describe the sympathetic nerve supply to the arm
Preganglionic sympathetic outflow is from T2-T9, these fibers synapse with the postganglionic nerve fibers in the stellate ganglion so doing a stellate ganglion block will block the sympathetic supply
Describe the anatomic location of the stellage ganglion.
Located between the base of the C7 transverse process and first rib.
- behind carotid sheath and vertebral artery
- recurrent laryngeal nerve is nearby
- pleura is close
After performing a stellate ganglion block, how can you tell if you were successful?
Expect Horner’s syndrome: ptosis, miosis and anhidrosis= however this ONLY TELLS YOU IF YOU BLOCKED the sympathetics to the head and neck. You should use temperature monitoring to watch for increased temperature of the extremity.
What types of nerve fibers are blocks with a stellate ganglion block?
preganglionic B fibers and postganglionic unmyelinated C fibers
Please review local anesthetic sections
please review local anesthetic sections
How can you treat CRPS?
- physical therapy (early and aggressive)
- if pain is SMP (sympathetically mediated) can use series of sympathetic blocks
- pain medications
What are drug options for treatment of CRPS
If pain is SMP…
- oral sympatholytic agents: phenoxybenzamine, prazosin, topical clonidine
Tricyclic antidepressants are first line treatment, anticonvulsants (gabapentin, pregabalin), corticosteroids and opioids
How can you do a Bier block in the diagnosis and treatment of CRPS?
Bier block wit phentolamine causes alpha adrenergic block and can be used to identify patients with SMP and acts as predictor before more invasive blocks are done
