Low Back Pain Flashcards
Where are the majority of pain meds aquired from?
Family or friends
only 17% prescribed by doctor
What are ‘red flags’ for pain?
- Bowel or bladder dysfunction • Impotence
- Fever/chills; weight loss
- Lymphadenopathy
• New onset in children/adolescents or age > 50
- Saddle anesthesia
- Motor deficits at multiple levels
Challenges in dx pain
- Perceived differently by different people
- Strongly influenced by psychological & social factors
• May coexist with mental illness & addiction
Challenges in dx LBP
“an illness in search of a disease”
–difficult to specifically identify if muscular, ligamentous/tendinous, facet joint or discogenic in origin
Nociceptive Pain= _______
Inflammation of soft tissue causes activation of nociceptor terminals in skin
Inflammatory chemicals released from blood stream, immune cells
Chemicals activate receptors on free nerve endings of ____ Sensitize nociceptors lower threshold, respond more
: soft tissue damage
C fibers
Mild: infection, rash
Severe: rheumatoid arthritis, gout, tumor in soft tissue
these are examples of what type of pain
Nociceptive pain
What can be used to treat soft tissue or nociceptive pain?
NSAIDs reduced inflammatory pain; opioids effective
Neuropathic pain=
: nerves directly damaged
Direct damage to nerves in PNS or CNS
(cut, compression, loss of blood supply & oxygen to nerves)
Burning, electrical quality; Allodynia to light touch common
Post herpetic neuralgia after “shingles” infection
Diabetic neuropathy
Severe nerve entrapment
Ex of Neuropathic pain
resistant to NSAIDS and opiates
Pain is carried in the ______ pathway in several ascending fibers that carry infor about pain and temperature to cortex
Anterolateral System: enters at DRG and crosses soon after through the anterior commisure into the anterolateral tract
• Noxious mechanical, thermal, chemical stimuli activate action potentials in free nerve endings of
AS or C-fiber nociceptors in skin (also muscle, joints, bones)
mediate first pain: fast, sharp, pricking, short-lasting, protective response, escape damage
AS fibers
mediate second pain:delayed, burning quality, long-lasting, chronic
C-fibers
Spinal cord: Central processes of nociceptors enter lateral dorsal horn via ______of Lissauer and Synapse on spinal cord neurons in
Dorsal lateral tract
superficial dorsal horn Lamina I/II or V
Synapse: Nociceptors release ____and ____ which activate receptors on spinal neurons
glutamate and substance P
Majority of 2nd order neurons terminate in thalamus
Most prominent pain pathway
Mediates discriminative aspects of pain and temperature sense
Location, intensity, duration of noxious stimulus
Spinothalamic Tract
Spinothalamic tract:
In thalamus, axons from body terminate in 2 nuclei:
a) Ventral Posterior Lateral (VPL) nucleus
b) Central Lateral Nucleus
receives pain info from body
is principal relay nucleus for discriminative pain info from body
Localizes where noxious stimulus on body occurred, how intense, qualities
Ventral Posterior Lateral (VPL
3rd order axons from VPL project to
SI cortex (Areas 3b, 1, 2)
Involved in emotional suffering during chronic pain & memory of painful events
is not somatotopically organized
Central Lateral Nucleus
3rd order axons from CL project to
many areas of cortex, Limbic cortex (cingulate gyrus; hippocampus, amygdala)
Reticular formation processing mediates changes in level of attention to painful stimuli
Involved in emotional, arousal, attention, affective response to noxious stimulus
Spinoreticular tract (located in medulla and pons, 2nd order neurons end up here)
stimulates descending control pathways that project down to spinal cord and inhibit pain signals coming up
Spinomesencephalic tract
Some 2nd order axons terminate in midbrain in the superior colliculus and ______
Other neurons in PAG send axons back down to spinal cord = descending control neurons, pathways
Periaqueductal Gray (PAG)
Thalamic neurons also project to:
2) ________
Processes emotional component of pain:
Fear, anxiety, depression, anger, attention
Cingulate gyrus: part of limbic system
Thalamic neurons project to:
_____ Processes info on internal, autonomic state of body (heart races, breathing rapid, mouth dry, muscles tense, can’t sleep)
also integrates discriminative, affective, emotional, cognitive components of pain
Insular cortex:
Patients perceive stimulus as noxious, but don’t care. Emotional response inappropriate
Lesion insular cortex: “Asymbolia for pain”
Descending pathways inhibit pain can be activated by
- activation by Spinomesencephalic tract
- exogenous opioids
Neurons with cell bodies in PAG
Send axons to _____ and send axons to _______
These neurons send axons to spinal cord
Synapse on inhibitory interneurons or Spinothalamic tract neurons (inhibit).
Suppresses transmission of ascending noxious info to thalamus and cortex
Raphe nuclei (medulla) and Locus ceruleus (pons)
Imaging in Low Back Pain: is xray a good option?
• Plain xrays—frequently ordered but have a very low yield of findings; doesn’t change management; poor relationship between radiographic abnormalities & signs/symptoms of LBP
When would we order an xray for LBP?
- Rule out infectious or malignant process
- Assessing patient with objective neuro abnormalities
• Identify compression fracture
Pros and Cons of MRI for LBP
Advantages:
–diagnosing disc disease, spinal stenosis, infection, neoplasm
–eval in case of intractable pain, neuro deficits
Disadvantages:
–presence of abnormal findings does NOT correlate well with clinical symptoms
ie. you may see herniated discs in up to 25% of asymptomatic people
How do we tx LBP
Acute LBP (no previous surgical procedure)
• 80 to 90 % will recover after 6 weeks, no matter what treatment is prescribed
• Only 1% eventually require surgery
• Patient education is crucial
• Cornerstone of treatment = physical exercise
Descending pain pathways
a. Originate in the ____ region of the midbrain and nuclei of the rostro-ventral medulla.
b. Descend in dorsolateral funiculus to dorsal horn
c. Release __________
d. Inhibit the activity of ascending pain pathways.
periaqueductal gray
norepinephrine, serotonin and enkephalin.
- Mu agonist
- Low oral to parenteral potency ratio - about 3 or 4 to 1
- Available in injectable, oral, oral sustained release and suppository forms. - Duration of analgesia – 4 - 5 hours.
• Morphine
- More lipophilic than morphine
- Converted to 6-mono-acetyl morphine and morphine
- High abuse potential
- Can be less expensive on the street than oxycodone
Heroin – diacetyl-morphine
- chemically, a phenylheptylamine - μ agonist
- Equipotent with morphine; has good oral availability
- Longer duration of action
- Used in t_reatment of opioid abuse and chronic pain._
Methadone
– structurally related to meperidine - μ agonist
- 100 X as potent as morphine
- Short-acting – 1 to 1.5 hours
- Available in injectable form and as transdermal patches
Fentanyl
For mild to moderate pain: Morphine-like efficacy is not achievable at any dose of____.
Codeine
are effective in treating moderate to severe pain.
Oxycodone and Hydrocodone
Some codeine is metabolized to
morphine
Most common ED visits relating to opiods are due to
oxycodone, hydrocodone, methadone
Opioids for chronic nonmalignant pain
Setting goals:
—improve pain control (“pain free” isn’t realistic)
—improve function
—provide relief of associated symptoms (ie anxiety or sleep problems)
What can we use to assess peoples risk for opiod addiciton
Opiod risk tool
Patient Health questionaire (PQH-9)
CAGE
What are some Non-opioid Adjuvant Medications:
1) Tricyclic antidepressants ie. amitriptyline 10-25 mg at bedtime
2) Selective Serotonin Reuptake Inhibitor (SSRI) ie. citalopram (Celexa) 20 mg daily
3) Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)ie. duloxetine (Cymbalta) 60 mg daily
***
Release of serotonin, norepinephrine to inhibit the ascending pain pathway
When choosing an opiod what do we need to condiser?
Pattern of pain
Fast on / fast off = most “rewarding”; higher addiction potential
Patients have different effects & different side effects Mu polymorphisms
Genomic differences in metabolism
Decrease in response to a drug as a result of repeated treatment with that drug.
Rapid – Nausea and vomiting
More Gradual – Analgesia, Euphoria, Respiratory Depression, Endocrine Effects
Little or None – Constipation, Miosis
Cross-Tolerance – between drugs of the same class
Opioid Tolerance
Signs of physical dependence on morphine (morphine withdrawl)
drug seeking, restless, lacrimation, sweating, yawning, anorexia, dilated pupils, irritable, chills and aches
—a state of adaptation
Tolerance & withdrawal are not required as criteria for addiction (Substance Use Disorder), because anyone taking opioids chronically( whether appropriately prescribed or not) will develop tolerance and experience withdrawal if meds are abruptly discontinued.
Physical Dependence
—primary, chronic, neurobiologic disease
- -impaired control over drug use
- -craving
- -compulsive use
–continued use despite harm
Addiction
Risk of OD
Decreased Tolerance—i.e. after a detox program, hospital stay, jail
Mixing opioids, especially in combination with benzodiazepines, alcohol
Other health issues (asthma, liver & heart disease, AIDS, malnourishment)
Previous overdose
Mode of administration
Pattern in heroin and opiod deaths recently
death from opiods is higher but has leveled off
herioin is lower but has increased in recent years
demographic for herion use and deaths
men, and huge increase in white recently especially midwest and northeast
opiod antagonist, non addictive prescription med that works if person has opiods in their system ONLY
IM, IV, SC and can induce withdrawl in opiod dependent person
Naloxone
Signs of opiod abuse disorder
Euphoria, craving, drug seeking, withdrawl
Tx options for opiod abuse
Methadone
Suboxone
Naltrexone
How are we decreasing prescription opiod abuse?
• Prescriber education and appropriate practice guidelines.
Prescription Drug Monitoring Programs.
Engineering prescription opioids to prevent use by routes of administration other than intended. For example snorting or injecting oral forms of drugs.
• Suboxone – Adding naloxone to buprenorphine to prevent injection.
Microencapsulation of drugs to prevent crushing time-release preparations.
Zohydro ER – extended release hydrocodone – no protection against abuse
