Pain Boards Flashcards
Describe the difference between migraines, cluster headaches, tension-type headaches, and chronic paroxysmal hemicrania.
Migraines
- Usually associated with nausea, vomiting, and sensitivity to light/sound/smells.
- An aura (visual/sensory/motor symptoms) may
precede the attack although migraine without aura is more common
- Pain is usually unilateral and throbbing
- Episodes can last hours to days
- Believed to involve cortical spreading depression, activation of the trigeminovascular system, and CNS modulation of the pain-producing structures of the cranium
- Can be triggered by abrupt decreases in levels of estrogen
Cluster headaches
- Associated with ipsilateral lacrimation, eye redness, eyelid edema, stuffy nose, rhinorrhea, and sweating
- Repetitive headaches that occur at the same time each day
- Episodes last minutes to hours.
- Can occur for a week to several months and are followed by a period of remission
- Can be treated with 100% oxygen
Tension-type headaches
- Bilateral, pressing/tightening sensation.
Chronic paroxysmal hemicrania is like a cluster headache, but episodes are shorter and more frequent.
How should you treat a pt with known contrast allergy, but who requires a procedure with contrast?
Pretreatment at 12 and 2 hours pre-procedure with Prednisone, Ranitidine, and Diphenhydramine. Pt should also receive 25 mg IV Diphenhydramine immediately pre-procedure.
What factors determine local anesthetic potency, speed of onset, and duration of action?
Potency- lipid solubility
Onset - pKa
Duration- protein binding
How does Botox work?
Botox produces localized flaccid paralysis by blocking the release of acetylcholine at the neuromuscular junction.
What is Carbamazepine used for? How does it work? What are the common side effects? What type of monitoring is required?
Drug of choice for trigeminal neuralgia
Selectively blocks Na channels on active nerve fibers, and has no effect on normally functioning C and A-delta fibers
Main side effects are nausea, vomiting, and sedation
Pts should have blood tests every 2 to 4 months, due to risk of agranulocytosis and aplastic anemia
What is Topiramate used for? How does it work? What are the side effects?
Used for neuropathic pain
Affects sodium and calcium channels, enhances the action of inhibitory GABA, and inhibits excitatory glutamate receptors
Side effects include weight loss, sedation, kidney stones, and ocular glaucoma
How do prostaglandins enhance the transmission of pain?
They increase the release of neurotransmitters such as substance P and glutamate from primary neurons, increase the sensitivity of second-order neurons, and inhibit the release of descending inhibitory neurotransmitters
What is Nabumetone? What are the benefits?
Nabumetone is an NSAID prodrug which needs to be converted to its active form
Theoretically has fewer gastric side effects, but this is unproven
How and where does Baclofen work?
Baclofen is a GABA-B receptor agonist that binds to presynaptic receptors in the dorsal horn of the spinal cord
What is the mechanism of action of various muscle relaxants (Baclofen, Carisoprodol, Tizanidine, Cyclobenzaprine)?
Baclofen - GABA-B agonist
Carisoprodol (SOMA) - inhibits descending reticular activating system
Tizanidine (Zanaflex) - central alpha-2 agonist
Cyclobenzaprine (Flexeril) - effects on brain stem
What are some common TNF inhibitors? What are they used for? How do they work?
Common inhibitors include Infliximab (Remicade), D2E7 (Humira), and Etanercept (Enbrel)
Used for the treatment of rheumatoid arthritis
Inhibit TNF, reduce markers of inflammation, and slow structural damage
Describe the effects that each opioid receptor is responsible for.
Mew-1
- supraspinal analgesia
Mew-2
- spinal analgesia
- dependence, respiratory depression, miosis, GI effects, pruritis
Delta
- supraspinal and spinal analgesia
- euphoria
Kappa
- spinal analgesia
- sedation, dysphoria, respiratory depression
What are the three molecular classes of opioids?
1) Pheneathrenes
- morphine, hydromorphone, codeine, oxycodone, oxymorphone, and hydrocodone
2) Phenylpiperidines
- meperidine, fentanyl, sufantanil, alfentanil, and remifentanil
3) Diphenylhepatanes
- methadone and propoxyphene
Aside from pain control, what use does Meperidine have? What are the side effects?
May have a beneficial effect in the setting of post-anesthetic shivering
Side effects include cardiac effects (orthostatic hypotension and cardiac depression), anticholinergic effects, neurotoxic effects due to accumulation of metabolite (worse with renal failure), potential for serotonin syndrome (when mixed with MAOIs, SSRIs, Tramadol, or Methadone), and local anesthetic effects
A pt with a clean history and I signs of misuse is requiring almost 5 times the originally prescribed oxycodone dose to control their pain. What is a possible explanation?
Pt may have genetically low levels of the cytochrome P450 enzyme required to metabolize oxycodone into oxymorphone
- Occurs in about 10% of pts
What nerve root is tested when checking the following reflexes: biceps, brachioradialis, triceps, patellar, Achilles
Biceps - C5
Brachioradialis - C6
Triceps - C7
Patellar - L4
Achilles- S1
What information can an EMG/NCS give you?
Site of injury (anterior horn, spinal root, plexus, nerve, NMJ, or muscle)
Type of nerve involved (motor, sensory, or autonomic)
Nature of pathology (demyelination or axonal degeneration)
Time course (acute or chronic)
How would you perform a maxillary nerve block?
- mandibular notch is identified
- 22 gauge needle is advanced perpendicular to the skin at the posterior inferior border of the notch
- needle is advanced until it hits the lateral ptyergoid plate
- needle is then withdrawn slightly and redirected anteriorly superiorly
- needle is advanced toward the pterygopalatine fossa until a parasthesia is obtained
When performing a lumbar sympathetic block, there can be inadvertent nerve block. Which nerve is most commonly blocked and how does it manifest?
The genitofemoral nerve is very susceptible at the L4-5 level
Manifests as weakness and numbness in the groin, anterior thigh, and quads
What is Tramadol’s mechanism of action? What type of patients should it be avoided in?
Mechanism includes agonism at the mu receptor and inhibition of norepinephrine and serotonin reuptake
Should be avoided in pts with seizure history (can lower seizure threshold) and in pts taking SSRIs (increases risk of serotonin syndrome)
Describe primary afferent neurons. What are the different types?
Primary afferent neurons have cell bodies in the DRG and axons that reach out to peripheral sites
- No spontaneous activity
- Increased activity corresponds with increased stimuli intensity
Three main types:
A-beta (large myelinated) - rapid speed - specialized endings
A-delta (small myelinated) - intermediate speed - low threshold - specialized endings
- responsible for “fast epicritic (1st) pain”
C (small unmyelinated) - slow speed - high threshold - free nerve endings
- responsible for “slow protopathic (2nd) pain”
What is the significance of the spinal rexed lamina?
Spinal rexed lamina are the site of secondary nociceptive neurons
Also the site of opioid receptors
Lamina I - marginal zone = “nociceptive specific”
Lamina II - substantia gelatinosa = highest density of nociceptors
Lamina V - nucleus proprius = “wide dynamic range” neurons
Describe the ascending pain pathways from the dorsal horn.
Spinoreticulothalamic tract = light touch
- ipsilateral, ventrolateral
Spinothalamic tract = pain
- contralateral, ventrolateral
- two main routes
1) lateral thalamus to somatosensory cortex = sensory and discriminative aspects of pain
2) medial thalamus to cingulate and insula = emotional aspects of pain and autonomic reflex responses
Define hyperalgesia, allodynia, paresthesia, dysesthesia, and hyperpathia.
Hyperalgesia = exaggerated nociceptive response to a moderately noxious stimuli
Allodynia = nociceptive response generated by a normally innocuous stimulus
Paresthesia = abnormal sensation (not necessarily pain)
Dysesthesia = spontaneous pain
Hyperpathia = a state in which pain is persistent, radiates, and may become amplified
Describe how tissue injury leads to peripheral and central sensitization. What receptor is involved in central sensitization?
Peripheral sensitization is due to:
- Persistent/increased spontaneous nociceptor discharge
- Enhanced response to stimuli
Central sensitization (“wind up”) due to:
- Repetitive C fiber input
- Increased response to stimuli from increased kinase activity and changes in gene transcription
- Enhanced receptive field size due to collateral nociceptor innervation
NMDA receptor is thought to be involved in central sensitization
- NMDA receptors are composed of NR1, NR2 (A, B, C, and D), and NR3 (A and B) subunits
- The NR2B subunit appears particularly important for nociception
Describe the changes/mechanisms that lead to neuropathic pain after nerve injury.
Widespread changes include increased activity of sodium channels and decreased activity of potassium channels, leading to increased afferent activity
Peripheral changes
- Retrograde chromatolysis
- Wallerian degeneration (starts distally; slow 1 mm/day; faster peripherally compared to centrally; motor faster than sensory)
- Sprouting and neuroma formation
- Invasion of inflammatory cells
Central changes
- Changes in the DRG including alteration of protein, channel, and receptor expression
- Increased DRG spontaneous activity
What is the mechanism by which opioids produce analgesia
Opioid receptors alter the conductance of potassium and calcium ion channels
Inhibit the release of neurotransmitters presynpatically
Inhibit neuronal firing via hyperpolarization postsynaptically
What are the concerns regarding migraine medications that contain Propoxyphene?
Issues with Propoxyphene:
- Daily use my cause rebound headaches
- Has been associated with cardiac dysrhythmias
- Metabolism occurs in the liver to norpropoxyphene which can cause toxic side effects
- Has not been shown to be any stronger than aspirin
Define physical dependence.
Physical dependence - state of adaptation that is manifested by a withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, and/or administration of an antagonist
What are the contraindications for stellate ganglion block?
Absolute contraindications
- Anticoagulation
- Pneumothorax on the contralateral side (due to high risk of pneumothorax on side of procedure)
- Recent MI (due to blockade of cardiac accelerator fibers)
Relative contraindications
- Glaucoma and impaired cardiac conduction
Placement of a spinal cord electrode at which cervical levels will cover the distribution for: upper neck pain, radial nerve pain, median nerve pain, and ulnar nerve pain?
Upper neck pain = C2-3
Radial nerve pain = C4-5
Median nerve pain = C5-6
Ulnar nerve pain = C6-7
If a stellate ganglion block is performed and shows technical success (ptosis, miosis, nasal congestion, etc.) but does not cause a change in temperature or pain, what is the likely reason?
In some cases the upper extremity may be supplied by the T2 and T3 grey rami communicantes (Kuntz fibers)
- Do not pass through the stellate ganglion
- Have been implicated in inadequate relief of sympathetically maintained pain despite a good stellate ganglion block.
Describe the metabolism of local anesthetics.
Amide local anesthetics are metabolized in the liver
Ester local anesthetics are metabolized in the plasma by plasma pseudocholinesterase
- Metabolism results in the formation of PABA, which is associated with allergic reactions
The genitofemoral nerve is made up of which nerve roots?
L1 and L2
Describe intervertebral disk anatomy
The inner nucleus pulposis is made up of mostly water but also some Type II collagen
The outer annulus fibrosis is mostly Type I collagen
What is the Dallas classification of IVD annular tears?
Grade 0 = normal disk
Grade 1 = contrast leaks to inner 1/3 of annulus
Grade 2 = contrast leaks to middle 1/3 of annulus
Grade 3 = contrast extends out to outer 1/3 of annulus
Grade 4 = contrast leaks to outer edge of annulus with concentric spread
Grade 5 = complete rupture
What receptors do opioids block in the spinal cord?
Mu and Kappa receptors
What is the treatment for a brachial plexus avulsion injury? What are the side effects?
Treatment is radiofrequency DREZ lesioning
Side effects include motor weakness, sensory deficits, and ataxia
How does nerve compression lead to neuropathic pain?
Nerve compression leads to hypoxia/damage to large myelinated nerve fibers
This loss of segmental inhibition leads to unopposed C fiber stimulation
Describe post-herpetic neuralgia
Caused by Herpes Zoster (Shingles)
- Virus stays dormant in DRG
Most commonly affects thoracic dermatomes
- Can also affect the opthalmic division of the trigeminal nerve (V1)
Characterized by pain that persists 30 days or more after rash onset
- Due to ischemic loss of myelinated fibers
Affects women more than men
What are the causes of central pain? What is the theorized mechanism? Are there any treatment options?
Causes:
- Stroke
- Almost 90% of all central pain is caused by CVAs, but less than 10% report pain within the first year - Spinal cord injury
- Multiple sclerosis
Mechanism is thought to involve disruption or injury of the spinothalamocortical tract
Motor cortex stimulation may be a possible treatment
What signs/symptoms are seen if local anesthetic is accidentally injected around the brain stem?
Bilateral headaches
4th or 6th nerve palsies
Pupillary changes
When performing a glossopharyngeal nerve block, which nerves are also commonly blocked??
Spinal accessory nerve
- Weakness of the SCM and trapezius
Vagus nerve
- Reflex tachycardia
The trigeminal ganglion lies in what structure?
Within Meckel’s cavity
Describe the “drug schedule”
The drug schedule ranks drugs based on abuse potential: Schedule V drugs have the lowest potential, while Schedule I drugs have no approved medical indications (ie Heroin)
Schedule II includes most opioids
Schedule III includes mixed acetaminophen-opioids and Tramadol
What is the best test to order if you are concerned about diskitis?
ESR
What are some excitatory neuromediators? What about inhibitory neuromediators?
Excitatory neuromediators: Glutamate Aspartate Substance P Neurokinin Bradykinin CGRP BDNF
Inhibitory neuromediators: GABA Glycine Enkephalin Beta-endorphin
Which part of the hypothalamus partly controls the sleep/wake patterns and may be altered in chronic pain?
The suprachiasmatic nucleus
Where are opioid precursors and their respective peptides found in the brain?
Amygdala
Hypothalamus
PAG matter
Raphe Magnus
What nerve is involved in cubital tunnel syndrome?
Ulnar nerve
What two tendons are involved in de Quervain’s Tendosynovitis?
Extensor pollicis brevis
Abductor pollicis longus
Describe the epidemiology and clinical features of CRPS. What is the difference between Type I and Type II? What is the most common sign and symptoms? What part of the body are the worst complications of CRPS seen?
Epidemiology
- Average age is in the 40s
- Women 3x than men
Clinical features
- Pain (spontaneous, burning, hyperalgesia, allodynia)
- Vasomotor changes - dilated (red) vs constricted (white)
- Sudomotor changes - increased (wet) vs decreased (dry)
- Edema
- Trophic changes (hair and nails)
Type I - no demonstrable nerve injury
Type II - known peripheral nerve injury
Worst symptoms are seen in the lower extremities
Most common sign = allodynia
Most common symptoms = decrease range of motion
What is the target for a stellate ganglion block? What is it used for? What are some known side effects?
Target is the transverse process of C6 (Chassaignac’s Tubercle)
- However the stellate ganglion itself actually lies anterior to the neck of the first rib and the transverse process of the C7 vertebra
Used for upper extremity and truncal neuropathic pain and CRPS
Can cause Horner’s syndrome (ptosis, miosis, and enopthalmos)
Can cause recurrent laryngeal nerve paralysis or even phrenic paralysis
What is the target for a celiac plexus block? What organs does it cover? What are known side effects?
Target is the L1 or L2 vertebral level
Covers the pancreas, liver, gallbladder, omentum/mesentery, and the GI tract from stomach to transverse colon
Known to cause orthostatic hypotension and increased gastric motility (diarrhea)
What is the target for lumbar sympathetic block? What is it used for?
Target is the L3 or L4 vertebral level
Used for lower extremity neuropathic pain and CRPS
What is the target for a superior hypogastric block? What is it used for?
Target is the L5 vertebral level
Used for chronic pelvic pain
Describe the innervation of vertebral facet joints.
Each individual facet joint is innervated by medial branches from that level and from the level above
Describe the origin of both the greater and lesser occipital nerves.
Greater occipital nerve = dorsal rami of C2
Lesser occipital nerve = ventral rami of C2 and C3
Describe some characteristics of phantom limb pain.
Pain is present in 60-80% of amputees
- Severe pain in 5-10% of cases
- Pain usually within the first week after amputation for vascular causes; much later (years) for other causes
- Patients who develop early pain are more likely to suffer from long-lasting pain
- Pain is usually intermittent and frequency/intensity tend to decline over time
The sensation is more vivid in the distal extremity
- Limb sensations “telescope” with time - the proximal part of the limb disappears first
Not reliably prevented with epidural blockade
Equal prevalence between men and women
Preamputation pain increases the risk of phantom pain
Describe the innervation of the sacro-iliac joint.
L4 medial branch, L5 dorsal ramus, S1-3 lateral branches
Which nerve is most commonly injured during a procedure in the lithotomy position?
The common peroneal nerve
What is meralgia parasthetica? How does it present? What is the cause?
Meralgia parasthetica is numbness and pain in the anterolateral thigh.
It is caused by entrapment of the lateral cutaneous femoral nerve by the inguinal ligament or fascia lata.
Describe gate theory.
Stimulation of A-beta fibers inhibits the firing of dorsal horn neurons in lamina V by activating inhibitory interneurons in lamina II
Describe the 3 main patterns of cancer pain.
Incident pain
Spontaneous pain
End of dose pain
What are the landmarks of the piriformis muscle? Describe piriformis syndrome.
The piriformis muscle extends from the anterior sacrum to the greater trochanter
- Responsible for lateral rotation and hip abduction
Piriformis syndrome presents with sciatic-like pain
- Worse pain with sitting
- Due to pressure on the passing sciatic nerve by the piriformis muslce
- Positive piriformis stretch sign (pain with flexion, adduction, and internal rotation)
What muscles make up the pelvic floor?
Obturator internus
Piriformis
Coccygeus
Levator ani
Describe the signs of C5 root pathology.
Pain in neck, shoulder, anterolateral arm
Numbness in the deltoid area
Weakness of deltoid and biceps
Abnormal biceps reflex
Describe the signs of C6 root pathology.
Pain in neck, shoulder, lateral arm
Numbness in dorsal thumb and index finger
Weakness of biceps, wrist extension
Abnormal brachioradialis reflex
Describe the signs of C7 root pathology.
Pain in neck, shoulder, lateral arm, and forearm
Numbness in index/middle finger, dorsum of hand
Weakness of the triceps
Abnormal triceps reflex
Describe the signs of L4 root pathology.
Pain in the back, thigh, and shin
Numbness in the medial shin
Weakness with foot dorsiflexion
Abnormal knee reflex
Describe the signs of L5 root pathology.
Pain in back, posterior thigh
Numbness on the top of foot
Weakness of the extensor hallicus longus
Describe the signs of S1 root patholgy
Pain the back and calf
Numbness of the lateral foot
Weakness of foot plantar flexion
Abnormal ankle reflex (not always consistent)
Describe Spurling’s Test.
A test for cervical radiculopathy
Neck is bent laterally towards the painful side
Axial load is added in line with the spine
Positive test is radiating pain in the normal distribution
When exposed to a local anesthetic, what is the order of the loss of nerve function?
- Pain
- Temperature
- Touch
- Proprioception
- Skeletal muscle tone
How do triptans work to help control migraines?
Stimulate 5-HT1B receptors located on cranial blood vessels causing vasoconstriction
Stimulate 5-HT1D receptors located predominantly on trigeminal nociceptors, inhibiting nociceptive transmission from pain-sensitive meningeal structures
How does propanolol work to help treat migraines?
Inhibits nitric oxide production
Antagonizes 5-HT1A and 5-HT2B receptors
Stabilizes membranes via inhibition of Glutamate receptors
Inhibits norepinephrine release
What kind of movements/maneuvers can improve the pain associated with spinal stenosis?
Sitting, stooping forward (walking uphill), and forward flexion all help decrease pain because they decrease the effective degree of stenosis
How do alpha-2 agonists (clonidine and dexmedetomodine) work?
Act in both the CNS and peripherally
Alter potassium and calcium conductance
Decrease neurotransmitter release presynaptically
Hyperpolarize the neuron postsynaptically, making it less likely to fire
What medications are commonly found in EMLA creams?
EMLA creams (eutectic mixtures of local anesthetics) can contain medications such as lidocaine, prilocaine, and/or tetracaine
Define the following types of pain: nociceptive, inflammatory, neuropathic, and functional
Nociceptive pain - adaptive transient pain in response to noxious stimuli
Inflammatory pain - transient pain hypersensitivity in response to tissue damage
Neuropathic pain - transient pain hypersensitivity in response to nerve damage
Functional pain - hypersensitivity in response to abnormal central input processing
Describe the motor and sensory innervation of the brachial plexus.
Axillary nerve
- motor to deltoid
- sensation to lateral arm
Musculocutaneous nerve
- motor to biceps
- sensation to lateral forearm
Radial nerve
- motor to wrist/thumb extension
- sensation between thumb and index finger
Median nerve
- motor for opposition/adduction of thumb
- sensation of index finger
Ulnar nerve
- motor for pinky abduction
- sensation of pinky
What is the difference between dermatomal pain, myotomal pain, and sclerotomal pain?
Dermatomal pain - pain in the distribution of a single nerve root innervating a specific area of skin
Myotomal pain - pain in the distribution of a group of muscles innervated by a single nerve root
Sclerotomal pain - pain emanating from an area of bone or fascia supplied by a single nerve root
Describe the innervation of the intervertebral disk. What is it’s blood supply?
Innervated by nerves that accompany the anterior and posterior longitudinal ligaments are are derived from the lumbar sympathetic trunks:
- sinuvertebral nerve
- grey rami communicantes
- lumbar ventral rami
Blood supplied by the lumbar artery
What is the mechanism of epidural steroid injections?
Steroids decrease inflammation by inhibiting phospholipase A2, thus inhibiting the formation of arachidonic acid, prostaglandins, and leukotrienes
- By restricting the formation of prostaglandins they may decrease sensitization of the dorsal horn neurons
Steroids may reduce inflammatory edema around the inflamed nerve root and improve microcirculation
They block the conduction of nociceptive C fibers
Describe the differences between alcohol and phenol when used for chemical neurolysis. How long does chemical neurolysis typically last?
Alcohol
- painful
- hypobaric
- immediate onset
- full effect in 3-5 days
Phenol
- painless
- hyperbaric
- delayed onset (15 min)
- full effect in 1 day
- higher risk of neuroma
Chemical neurolysis typically last about 4 months
What are the natural opioids? Semisynthetic? Synthetic?
Natural opioids = morphine and codeine
Semisynthetic opioids = heroin, hydrocodone, hydromorphone, oxycodone, oxymorphone, buprenorphine
Synthetic opioids = meperidine, methadone, fentanil, propoxyphene
What are some important characteristics of morphine?
Conjugated in the liver and excreted by the kidneys
Two metabolites
- M6G is an active metabolite with analgesic properties
- M3G can cause CNS activation (myoclonus and seizures) if it accumulates, often in patients with renal failure
What are some important characteristics of codeine?
A prodrug that is converted to morphine and slightly to hydrocodone
About 10% of people are poor metabolizers of codeine, resulting in variable relief
What are some important characteristics of buprenorphine?
A mixed agonist-antagonist
- partial mew agonist, kappa antagonist
Slow dissociation from mew receptor and prolonged effect are why it is used for treatment of opioid dependence
What are some important characteristics of Hydrocodone?
Most prescribed opioid in the USA
Often paired with acetaminophen
Metabolized to hydromorphone
What are some important characteristics of oxycodone?
Primarily mew selective
Metabolized to oxymorphone
What are some important characteristics of methadone?
Multiple mechanisms:
- mew and delta opioid agonist
- NMDA antagonist
- norepinephrine and serotonin reuptake inhibitor
Has very variable oral bioavailability
Can interact with many common medications
Side effects can outlast the analgesic effects
Can prolong QT interval
What are some important characteristics of meperidine?
Similar structure to atropine - can cause tachycardia
Metabolized to normeperidine, which can cause seizures
Should only be used for acute pain
What are some important characteristics of tramadol?
Multiple mechanisms:
- weak mew agonist
- inhibits norepinephrine and serotonin reuptake
- blocks nicotinic and muscarinic receptors
- inhibits NMDA receptors
Can cause serotonin syndrome when mixed with SSRIs or TCAs
What is the mechanism of Gabapentin and Lyrica?
Alteration of voltage-gated calcium channels by binding to the alpha-2-delta subunit
What must be proven for a successful malpractice suit?
The patient/plaintiff must prove:
- Duty - the physician owed the patient a duty
- Breach of duty - physician failure to fulfill duty
- Causation - a close causal relation between physician’s act and the resultant injury
- Damages - actual damages that occurred
How can you distinguish between medial and lateral epicondylitis?
With lateral epicondylitis, pain is increased with resisted wrist extension
With medial epicondylitis, pain is increased with resisted wrist flexion
Via radiographic screening, what is the prevalence of lumbar spondylosis? What about if its based on diagnostic blocks?
6% based on radiographic screening
15-45% based on diagnostic blocks
Technically, what is the first line agent for medical treatment of osteoarthritis?
Tylenol because OA is thought to be primarily non-inflammatory
However, NSAIDs have shown benefit as well
What is the blood supply of the spinal cord?
2 posterior spinal arteries and 1 anterior spinal artery
- Blood vessels arise from the segmental arteries of the aorta and from branches of the subclavian, vertebral arteries, and internal iliac arteries
- Anterior spinal artery responsible for about 80% of blood flow
- The largest feeder of the anterior spinal artery is the artery of Adamkiewicz that originates from between T8 and L3
What is the normal anteroposterior diameter of the spinal canal? What is considered relative stenosis? What is considered absolute stenosis?
Normal diameter is more than 12 mm
Relative stenosis is less than 10 mm
Absolute stenosis is less than 8 mm
Define neuropraxia.
Neuropraxia is nerve damage without any
disruption of the myelin sheath
- There is an interruption in conduction of nerve impulses
- There is a transient loss of motor conduction
- Little to no sensory conduction is affected
Describe the dermatomal distribution of the lumbar and sacral nerves.
L1 - Upper thigh and groin
L2 - Mid anterior thigh
L3 - Medial femoral condyle
L4 - Medial malleolus
L5 - Top of the foot
S1 - Lateral heel
S2 - Medial popliteal fossa
How many different types of voltage-gated sodium channels have been identified? Which seems to have a role in pain pathways?
9 types of sodium channels
Na-1.9 seems to have a specialized role in the pain pathway
What are the most important substances found in the descending inhibitory pathways of the CNS?
Serotonin and Norepinephrine
What are the diagnostic criteria for fibromyalgia? How is it characterized? How is sleep affected?
Diagnostic criteria:
1. Chronic widespread pain (CWP) defined as pain in all four quadrants of the body and the axial skeleton for at least 3 months
2. The finding of pain by 4-kg pressure on digital palpation of at least 11 of 18 defined tender
points
Characterized as primary or secondary:
- Primary - when work-up reveals no underlying cause
- Secondary - when some form of inflammatory or other pain condition is also diagnosed
- Fibromyalgia symptoms generally do not resolve even with resolution of rheumatologic disease
Effects on sleep:
- pts awaken feeling stiff, sluggish, and unrefreshed
- pts commonly awaken after a few hours of sleep (mid-insomnia) and are unable to sleep again until near morning (terminal insomnia)
- have no trouble napping during the day
What are the characteristic differences between large-fiber neuropathy and small-fiber neuropathy?
Large-fiber neuropathy leads to weakness, numbness, tingling, and loss of balance
Small-fiber neuropathy leads to pain, anesthesia, and autonomic dysfunction
What is intrathecal baclofen used for? What are the signs of overdose? What are the signs of withdrawal?
IT baclofen is used for antispasticity and muscle relaxation
Overdose symptoms include drowsiness, weakness, hypotonia, and respiratory depression
Withdrawal symptoms include diaphoresis, hyperthermia, hypotension, AMS, pruritis, and increased muscle tone
- Can be fatal
What is the concern regarding cervical transforaminal epidural injections?
The vertebral artery lies in the anterior neuroforamen
Why is fentanyl an ideal choice for transdermal and transmucosal administration?
High lipid solubility
Low molecular weight
High potency
What are the main parts of the opioid risk tool (ORT)?
Age
Personal and family history of substance abuse
History of sexual abuse
Presence of depression, ADD, OCD, bipolar, or schizophrenia
What is unique about clonazepam?
Clonazepam (Klonopin) binds to the Gaba-B receptor (unlike other benzos that bind to the Gaba-A receptor)
Used for neuropathic pain and muscle relaxation
Describe “Weaver’s bottom”
Ischial bursitis
Pain when sitting which goes away upon standing or lying on contralateral side
- pain promptly returns upon resuming a seated position
On physical examination, tenderness is evoked with palpation over the ischiogluteal bursa
What temperature range should be used to test warm temperature sensation? What about cold temperature sensation?
Warm temperature = 40 to 45 Celsius
Cold temperature = 5 to 10 Celsius
What finding on EMG/NCS can help differentiate between tumor-induced brachial plexopathy or radiation induced brachial plexopathy?
Presence of myokymia (continuous but brief involuntary muscle twitching that gives the appearance of wormlike rippling of the muscle) indicates radiation induced cause
What is the conversion from oral morphine to fentanyl patch?
Divide by 3
ie. 75 mg oral morphine daily to 25 mcg Fentanyl patch
What is the difference between spondylosis, spondylolysis, and spondylolisthesis?
Spondylosis = degeneration of the spine
Spondylolysis = fracture of the pars interarticularis
Spondylolisthesis = slippage of one vertebral body out of alignment
How does anterior spinal artery syndrome present?
Abrupt motor loss
Sphincter disturbance
Preservation of sensation to light touch but loss of pain and temperature.
What is the most common organism that causes epidural abscess after a procedure?
Staphylococcus aureus
What is unique about the pathophysiology of sickle cell disease pain?
It involves a combination of ischemic tissue damage and secondary inflammatory response
Describe the three types of pain seen in spinal cord injury.
Above-level pain - includes pain caused by compressive mononeuropathies (particularly carpal tunnel syndrome) and CRPS
Below-level pain - central pain caused by the spinal cord trauma
At-level pain - may have both peripheral (nerve root) and central (spinal cord) components that are difficult to separate
What is Ziconotide?
Derived from the toxin of the cone snail Conus magus
A neuronal-specific calcium-channel blocker that acts by blocking N-type, voltage-sensitive calcium channels
Must be administered intrathecally
Common side effects are dizziness, nausea, confusion, and headache
- Severe but rare side effects are hallucinations and suicidal ideation
What is meant by “whiplash”? What muscles are involved?
“whiplash” describes the resultant injury caused by an abrupt hyperextension of the neck from an indirect force
Muscles involved:
- Sternocleidomastoid
- Longus colli muscle
- Scalenes
Describe the system that rates drugs based on their safety for use during pregnancy.
Category A: animal studies and controlled human studies indicate no apparent risk to fetus and possibility of harm to the fetus seems remote
- multivitamins
Category B: animal studies do indicate a risk, but well controlled human studies have not demonstrated a risk
- acetaminophen, most opioids, ibuprofen, caffeine
Category C: animal studies indicate risk, but no controlled human studies have been done
- aspirin, ketorolac, gabapentin, triptans
Category D: positive evidence of human fetal risk, but in certain circumstances, the benefits of the drug may outweigh the risks involved
- amitriptyline, benzos, phenytoin, valproate
Category X: positive evidence of significant fetal risk, and the risk clearly outweighs any possible benefit
- ergots
What is the difference between impairment, disability, and handicap?
Impairment refers to a problem with a structure or organ of the body
- ie. spinal cord injury
Disability is a functional limitation with regard to a particular activity
- ie. inability to walk due to spinal cord injury
Handicap refers to a disadvantage in filling a role in life relative to a peer group
- ie. inability to work due to disability from spinal cord injury
What is the difference between McKenzie method exercises and Williams method exercises?
McKenzie method exercises are spinal extension exercises used for disk herniations and radiculopathy
Williams method exercises are flexion based exercises used for stenosis
What enzyme is responsible for metabolism of fentanyl and methadone?
CP450 CYP3A4
