Low Back Pain Flashcards by Meghan May

Where are the majority of pain meds aquired from?

Family or friends

only 17% prescribed by doctor

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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

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Challenges in dx pain

Perceived differently by different people
Strongly influenced by psychological & social factors

• May coexist with mental illness & addiction

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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

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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

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Mild: infection, rash
Severe: rheumatoid arthritis, gout, tumor in soft tissue

these are examples of what type of pain

Nociceptive pain

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What can be used to treat soft tissue or nociceptive pain?

NSAIDs reduced inflammatory pain; opioids effective

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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

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Post herpetic neuralgia after “shingles” infection

Diabetic neuropathy
Severe nerve entrapment

Ex of Neuropathic pain

resistant to NSAIDS and opiates

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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

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• Noxious mechanical, thermal, chemical stimuli activate action potentials in free nerve endings of

AS or C-fiber nociceptors in skin (also muscle, joints, bones)

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mediate first pain: fast, sharp, pricking, short-lasting, protective response, escape damage

AS fibers

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mediate second pain:delayed, burning quality, long-lasting, chronic

C-fibers

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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

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Synapse: Nociceptors release ____and ____ which activate receptors on spinal neurons

glutamate and substance P

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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

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Spinothalamic tract:

In thalamus, axons from body terminate in 2 nuclei:

a) Ventral Posterior Lateral (VPL) nucleus
b) Central Lateral Nucleus

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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

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3rd order axons from VPL project to

SI cortex (Areas 3b, 1, 2)

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Involved in emotional suffering during chronic pain & memory of painful events

is not somatotopically organized

Central Lateral Nucleus

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3rd order axons from CL project to

many areas of cortex, Limbic cortex (cingulate gyrus; hippocampus, amygdala)

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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)

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stimulates descending control pathways that project down to spinal cord and inhibit pain signals coming up

Spinomesencephalic tract

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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% e**ventually require surgery • **_Patient education is crucia_**l **• 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