Chronic Pain Flashcards
MC reason pts seek medical care; more than DM, heart dz and cancer combined
pain
difference between chronic vs acute pain?
The separation between the acute phase and chronic phase is usually at the 3 month point, or after 90 d of continued pain
Constant chronic pain will allow for ____, leading to normal BP, heart rate, respirations.
physiologic adaptation
Intermittent chronic pain will imitate _____, and physiologically cannot adapt.
acute pain
Imaging studies have shown that chronic pain is associated with changes in the brain, what are the main findings?
- decreases in gray matter —mainly in brainstem and somatosensory cortex
- altered brain chemistry
- structural changes in nerve tracts
- altered brain network connectivity
= altered behaviors
what is the relationship between time of intervention and chronic pain
earlier the intervention, the better success rate for tx
what are the three neurotransmitters that have an excitatory effect?
- substance P
- CGRP
- glutamate
everything else is inhibitory
40-50 m/sec; Thick myelination. Low threshold, mechanoreceptors. Fastest. Light touch, Pressure, hair movement. Not usually pain.
which primary afferent fiber?
A-beta
(>10 & <40 m/sec), Thinly myelinated. high & low threshold mechanical & thermal receptors. The first, ‘sharp’ and ‘intense’ pain sensation.
which primary afferent fiber
A-delta
(<2 m/sec), Unmyelinated. Free nerve endings, High threshold to thermal, mechanical or chemical insults. 75% of all afferent fibers. Prolonged, ‘burning’ that follows the initial A-delta stimulus.
which primary afferent fiber?
C
The cell body lies outside of the CNS in the ?
dorsal root ganglia?
The nerve then enters the spinal cord via the ?
dorsal (posterior) root.
First neuron synapse occurs at _____, and ______
spinal dorsal horn (nociception from primary afferents)
dorsal column nuclei (A-betas, light touch)
an instantaneous movement caused by the stimulus
reflex arc
what part of the brain releases NT and hormones to modulate and inhibit pain?
hypothalamus
difference between white vs gray matter?
white matter
- myelinated
- longitudinal tracts
- up and down
- signal conduction
gray matter
- segmentary structure
- side to side
- siganl process
- nerve roots are also gray matter
Regions of body where you might feel sensation
Related to spinal column and spinal cord
dermatomes
three main types of pain
- nociceptive (MC)
- neuropathic
- psychogenic
Aberrant activation of pain sensitive afferent peripheral nerves, due to noxious stimulation of somatic or visceral structures (i.e., celiac plexus.)
what type of pain?
nociceptive
nociceptive pain stems from activation of what type of fibers?
A-delta and C fibers by noxious stimuli
common nociceptive pain disorders
- Failed Back Surgery Syndrome
- Mechanical Spine disorders
- Arachnoiditis
- Degenerative Disk Disease
- Facet Joint Arthropathy
- Sacroiliitis
- Arthritis; OA, RA, Gout
- Cancer
Abnormal somatosensory processing in the PNS or CNS due to a primary lesion, neural injury or irritation, or
dysfunction.
Burning, stabbing, electrical sensations.
what type of pain?
neuropathic pain
Activation of what by glutamate increase spinal neuron sensitization
which increases perception of
pain?
NMDA receptors
When innocuous stimuli is painful; bedsheets, air, light touch.
what type of focal neurologic deficit?
allodynia
abnormal pain ‘like fire’
what type of focal neurologic deficit?
dysesthesia
increased perception of noxious stimulation; hurts worse than it should
what type of focal neurologic deficit?
Hyperalgesia
6 focal neurologic deficits
- allodynia
- dysesthesia
- hyperalgesia
- edema
- vasomotor changes
- trophic changes
common neuropathic pain disorders
- Diabetic neuropathy - Peripheral Nerve Injury, Reflex sympathetic dystrophy/CRPS I: No known obvious nerve injury.
- Complex Regional Pain Syndrome II/Causalgia
- phantom limb and post-amputation pain
- Post-herpetic neuralgia
- Central pain syndrome–CVA, MS, ALS, tumors, epilepsy, brain or spinal cord trauma, or Parkinson’s
disease - Trigeminal Neuralgia/tic doloureux/Atypical TN
- Occipital Neuralgia
- Ilioinguinal Neuritis
- Post-CA treatment pain; radiation/chemotherapy
difference between nociceptive vs neuropathic pain?
- nociceptive
- Mediated by receptors in the viscera, bone, dermis, muscle and connective tissues
- Exacerbated by positional change or
activity
- Usually opiate sensitive - neuropathic
- Damaged or dysfunctional nerve
tissue or damage to the CNS
- Resultant from tissue injury or pathology induced injury
- Usually not opiate sensitive
Persistent and chronic pain at one or more sites in which psychological factors are thought to play a role.
what type of pain?
Pyschogenic pain/Somataform disorder, defined
No nociceptive or neuropathic mechanisms
Not necessarily associated with secondary gain
Commonly linked with depression
Psychiatric and behavior management a must
Low rate of recovery
purpose of Pain Agreement?
To encourage patient compliance.
To facilitate an understanding between the patient and the doctor regarding the use of scheduled medications.
what is the pain agreement?
- not a legal doc
- DEA still breathes down your neck
- will help as long as YOU follow terms of the agreement
- frequent UDS
- pill counts
- communication with PCP
- pharmacists, consultants, and the local authorities. - ensure policy that unless pt has SE/allergy that the meds will not be changed until next refill is due
- insist f/u visits for med changesl avoid extensive use of phone-ins
With the pain agreement, the pt must:
- agree to one prescriber for meds
- must agree to undergo screening for compliance; UDS, saliva tests, serum testing
- agree that lost/stolen meds will not be replaced
- don’t forget to raper if necessary to avoid withdrawal. agree to replace only if pt provides police report - report one pharmacy for meds and should report if they change pharmacies
- bring back unfilled scripts and unused meds back for destruction
what adjuvant meds have a pain agreement?
- benzo
- class IV/V meds
Quick and good for acute pain, but
doesn’t demonstrate progressive
response to treatment accurately
for chronic pain.
Wong-Baker FACES scales
which pain questionnaire is for assessing the whole body?
McGill pain questionnaire
Provides a baseline to review and
accurately determines response
over time.
Brief Pain Impact Questionnaire
common diagnostic testing for pain
imaging: MRI/CT, xray, motion XR, US
NCS/EMG (electromyography)
bone scan
serum - CMP, thyroid, B12, DM, HgbA1C, RA panel, Lupus panels
Discography
a heightened response to a stimulus that causes pain
what is this term
hyperalgesia
diminished pain in response to a normally painful stimulus = hypo
what spinal PE test is used to test for HNP of the L-spine
SLR
Must be supine, reproduction of sciatica 30-70 degrees = Positive
Crossed SLR: +SLR on asx leg = high suspicion for HNP
crosses affected side, ankle on knee, compress flexed knee to check for SI issues or hip joint pathology
what is this spinal PE test?
patrick’s/faber
how to do zygomatic joint loading?
rotation and flexion of spine
elicits pain at contralateral facet joints
foot drop-toe dragging (steppage gait) is indicative of what?
inability to walk on heels; think L5 root compression, peroneal nerve damage, sciatica, cauda equina syndrome
what is the piriformis stretch?
Lat decubitus position, flex hip and knee of upper leg; positive if downward pressure produces pain from buttock to leg.
what is spurling’s test?
extend, rotate and tilt head then compress head; if radicular to ipsilateral side, then possible nerve root compression in mid or lower C-spine.
what is the axial copmression?
compression of C-spine by pressing on the head; positive neck pain or radiation=possible DJD or upper
C-spine nn impingement.
what is the Waddell’s Signs-malingere
Nonsensical/non-anatomical pain
Axial loading of skull producing low back pain
Rotation of shoulders and hips simultaneously with feet planted causing low back pain
SLRs differ when sitting or supine
Unexplained sensory pain or motor
weakness non-dermatomally
what is the hoover’s test?
supine, ask to lift weak leg. With both hands on heels, true ataxia will cause good leg to press down against your hand. Feigned weakness will not show that the good leg is supportive.
what is Embellishment of arm weakness
when testing for UE strength, a ratcheting ‘give-way’ weakness is elicited in the ‘bad’ arm. Testing both at same time you will notice that both arms ‘give-way.’
initial tx for pain
- PT/OT, return-to-work programs
- Surgical evaluation/treatment
- wt loss and lifestyle changes
- PO steroids, NSAIDs and other OTCs
- Antidepressants
- Membrane stabilizers/Anticonvulsants
- Antispasmodics
- Transcutaneous electrical nerve stimulation; TENS unit or newer E-stim units.
- Bracing/orthotics
- Anxiolytics (*cautionary)
- psychiatric care
when to refer for pain?
- outcomes aren’t successful.
- ‘complicated’ pt
- clear-cut pathology needs addressed interventionally.
- you aren’t comfortable with the tx needed; ie, injections.
- maintain a pt in good standing with chronic Rx therapy.
interventional pain management injectable options
- myofascial/trigger point injections (also w/ myobloc/botox)
- peripheral nerve blocks
- spinal nerve blocks
- sympathetic nerve blocks/plexus blocks
- epidurals: transforaminal and interlaminar
- intra-articular injections
- facet injections/median nerve blocks
Advanced Interventional Pain Management Strategies
- Radiofrequency Ablation (RFA)
- Chemodenervation
- Minimally Invasive Lumbar Decompression-MILD
- Interdiscal radiofrequency ablation
- Mechanical Spacers for stenosis, SI fusion
- Spinal Cord Stimulation
- Peripheral Nerve Stimulation
- Dorsal Root Ganglion stimulaton
what is spinal cord stimulation
- Stimulation of dorsal column of the spinal cord, dorsal root ganglion, or dorsal root entry zone
- For lumbar radiculopathy, peripheral neuropathy, CRPS of the extremities
- Used to be difficult to relieve low back pain, but getting much better with higher frequency stimulators
ways for peripheral nerve stimulation
- ilioinguinal neuralgia - ilioinguinal region in the abdomen
- somatic peripehral nerves
- median, ulnar, genicular, etc
- Causalgia, single nerve RSD,
post-CVA pain
- Intercostal nerve; intercostal neuritis, PHN - Occipital nerve
- Occipital neuralgia, cervicogenic HA
- Cluster HA, Migraines - Cranial nerves - Trigeminal neuralgia
Indications for Motor Cortex Stimulation
- Post-stroke pain
- Thalamic pain
- Anesthesia dolorosa “numb pain” 2nry to neurolysis
- Trigeminal pain
- Brachial plexus avulsion
- Stump pain
- Phantom pain
- Spinal cord injury pain
- CRPS Type I (RSD)
- CRPS Type II (causalgia)
- Post-herpetic neuralgia
indications for deep brain stimulation
- neuropathic pain
- anesthesia dolorosa
- trigeminal nuropathic pain
- post-strok pain
- thalamic pain
- post herpetic neuralgia
- spinal cord injury
- peripheral neuropathy - nocioceptive pain
- failed back syndrome
- cancer
- osteroarthritis
what is the sprint peripheral stimulator?
- stimulates peripheral nerves
- outpatient surgery to implant the lead
- wears stimulator for 2 months
- then stimulator is removed
- goal: permanently modulate the nerve after the stimulator is removed
limitations of conventional SCS
- unspecific - stimulation of broad range of nerve fibers versus pain- or disease-specific nerves
-
unstable
- postural effects on stimulation
- lead migration -
consuming
- energy loss to CSF demnds higher output, thereby impacting longevity
what is the MILD procedure?
tx for pain relief from symptomatic central lumbar canal stenosis
common intrathecal meds
Morphine
Baclofen
Hydromorphone
Fentanyl
Sufentanil: 7x stronger than fentanyl
Clonidine: decreases sympathetic response and vasomotor associated with neuropathic pain
Bupivacaine: Increases efficacy of
analgesics and for neuropathic pain.
Prialt (zyconotide): from sea snails
Octreotide: synthetic sandostatin (growth hormone)
alternative
- Chiropractic
- Biofeedback and hypnotherapy
- Dry needling
- Accupuncture
- Massage Therapy
- Non-FDA approved tx, research, and experimental tx (DREZ, brain mapping)
CDC Guidelines for Prescribing Opioids for Chronic Pain 2016
- Nonopioids should be first line therapy
- Establish treatment goals,
discontinuance - Discuss risks and realistic outcomes first
- Start immediate-release opioids first
- Prescribe lowest effective dosage 50-90 MME
- 3-7 days worth of opioids for acute pain
- Re-evaluate patient in 1-4 weeks for
benefit vs harm; q3 months to check
efficacy and DC or lower dose if no
positive outcomes - Evaluate risk factors prior to starting opioids; offer naloxone if past risk factors (previous OD, substance disorder) or if benzo use
- Review state drug monitoring program to ensure proper dispensing of medications
- Urine Drug Testing prior to starting opioids and minimum of annual UDS
- Avoid concurrent benzodiazepines and opioids
- Arrange tx for pts with opioid use disorder; consider buprenorphine or methadone (suboxone and methadone clinic) in combo with behavioral therapies
