ABEM Pain Medicine cheat sheet

A-delta fibers are thinly myelinated and conduct rapidly, producing sharp, well-localized first pain; C fibers are unmyelinated and produce slow, dull, burning second pain.

Nociceptive input enters the dorsal horn and synapses in laminae I, II, and V; projection neurons in laminae I and V decussate in the anterior white commissure and ascend in the lateral spinothalamic tract.

The substantia gelatinosa (lamina II) contains interneurons and opioid receptors that modulate afferent traffic before ascending transmission.

Gate control theory: large-diameter Abeta mechanoreceptor input activates inhibitory dorsal horn interneurons and reduces transmission from A-delta and C nociceptors.

Descending modulation runs from the periaqueductal gray to the rostral ventromedial medulla and then to the dorsal horn, using serotonin, norepinephrine, and endogenous opioids.

Mu opioid receptors are Gi-coupled: activation inhibits adenylyl cyclase, opens potassium channels, closes calcium channels, and reduces neurotransmitter release.

Local anesthetics block voltage-gated sodium channels from the intracellular side; inflamed tissue has a lower pH, increasing the ionized fraction and slowing onset.

NSAIDs inhibit cyclooxygenase-1 and cyclooxygenase-2, reducing prostaglandin synthesis; they do not inhibit the lipoxygenase pathway.

Peripheral sensitization involves prostaglandins, bradykinin, and substance P lowering nociceptor threshold; central sensitization involves NMDA receptor activation and wind-up.

Numeric rating scale uses 0 to 10; visual analog scale uses a 100-mm line; faces scales are used for young children or patients who cannot use numbers.

DN4 neuropathic pain screen: a score of 4 or more out of 10 suggests neuropathic pain; LANSS and PainDETECT are alternative screening instruments.

SOCRATES history framework: Site, Onset, Character, Radiation, Associated symptoms, Time course, Exacerbating and relieving factors, Severity.

Examination for neuropathic pain includes pinprick, light touch, temperature, vibration, and pressure testing to detect allodynia, hyperalgesia, and sensory loss.

Red flags in back pain include fever, unexplained weight loss, cancer history, night pain, bowel or bladder dysfunction, saddle anesthesia, and progressive neurologic deficit.

Imaging is not routinely indicated for nonspecific low back pain of less than 6 weeks without red flags or serious pathology.

Opioid Risk Tool scoring: 0 to 3 indicates low risk, 4 to 7 moderate risk, and 8 or more high risk for opioid misuse.

Nociceptive, neuropathic, and nociplastic pain require different treatment emphasis; nociplastic pain occurs without clear evidence of nociceptor activation or nerve injury.

Urine drug testing confirms adherence and detects nonprescribed substances; immunoassays require confirmation testing for unexpected results.

Acetaminophen adult maximum is 4,000 mg/day; a limit of 3,000 mg/day or less is used in hepatic impairment, chronic alcohol use, malnutrition, or low body weight.

NSAIDs carry gastrointestinal, renal, and cardiovascular risks; they are avoided in advanced chronic kidney disease, active peptic ulcer disease, and some anticoagulated patients.

Morphine metabolism produces morphine-6-glucuronide and morphine-3-glucuronide; accumulation in renal failure can increase analgesia and toxicity.

Meperidine metabolism produces normeperidine, a renally cleared metabolite that can cause myoclonus, agitation, and seizures with repeated dosing.

Methadone prolongs the QT interval and has a long, variable half-life; initiation requires low dosing and ECG monitoring in at-risk patients.

Buprenorphine is a partial mu agonist with high receptor affinity; it has a ceiling effect on respiratory depression and can precipitate withdrawal in patients taking full agonists.

Tramadol is a weak mu agonist and serotonin-norepinephrine reuptake inhibitor; it lowers seizure threshold and is contraindicated with monoamine oxidase inhibitors.

Gabapentinoids bind the alpha-2-delta subunit of voltage-gated calcium channels and reduce excitatory neurotransmitter release; gabapentin bioavailability saturates at higher doses.

Tricyclic antidepressants such as nortriptyline and desipramine are used for neuropathic pain; anticholinergic and cardiac effects warrant caution in older adults.

Medial branch blocks target the dorsal ramus medial branch; concordant relief of 80% or more on two diagnostic blocks supports radiofrequency facet denervation.

Transforaminal epidural steroid injection with particulate corticosteroid can cause spinal cord infarction through radicular artery occlusion; nonparticulate dexamethasone is often preferred.

Celiac plexus block is used for upper abdominal pain from pancreatic cancer and can produce orthostatic hypotension and diarrhea.

Stellate ganglion block at the C6 anterior tubercle produces Horner syndrome (ptosis, miosis, anhidrosis) and is used for complex regional pain syndrome of the upper limb.

Spinal cord stimulation delivers electrical pulses to the dorsal columns; paresthesia-based, high-frequency, and burst waveforms are used for persistent radicular pain.

Intrathecal drug delivery with morphine can cause catheter-tip granuloma, especially with high concentration or high daily dose; ziconotide is a nonopioid alternative.

Contraindications to interventional procedures include local infection, coagulopathy, inability to consent, and untreated systemic infection.

Fluoroscopy safety follows ALARA: minimize time, use pulsed mode, collimate the beam, and maximize distance from the radiation source.

Cognitive behavioral therapy targets maladaptive thoughts and behaviors maintaining disability and has strong evidence for improving function and distress in chronic pain.

Graded exposure gradually confronts feared movements in a planned hierarchy, reducing fear avoidance and restoring activity tolerance.

The fear avoidance model links catastrophic misinterpretation of pain to activity avoidance, deconditioning, and chronic disability.

Pacing alternates activity and rest before pain flares to prevent the overactivity-underactivity cycle and improve sustained function.

Operant conditioning programs reinforce well behaviors and reduce attention to pain behaviors, often within multidisciplinary programs.

Multidisciplinary pain programs combine medical, physical, and psychological care; they improve function and reduce healthcare use in selected chronic pain patients.

Pain neuroscience education explains central sensitization and pain biology; it is used with active rehabilitation rather than as a standalone treatment.

Yellow flags for poor recovery include catastrophizing, fear avoidance, low self-efficacy, anxiety, and work-related dissatisfaction.

The Controlled Substances Act places drugs in schedules II to V; schedule II prescriptions cannot be refilled and require a written or qualifying electronic order.

Prescription drug monitoring programs are state databases queried before prescribing controlled substances to identify multiple prescribers, high doses, and possible misuse.

Informed consent includes diagnosis, nature and purpose of the procedure, material risks and benefits, alternatives including no treatment, and patient affirmation.

HIPAA permits disclosure of protected health information for treatment, payment, and healthcare operations; other uses generally need authorization or de-identification.

OSHA bloodborne pathogen standards require exposure control plans, hepatitis B vaccination offers, and post-exposure evaluation for healthcare workers.

Evaluation and management coding requires documented history, examination, and medical decision-making or time; procedural codes are reported separately when appropriate.

Documentation of controlled substance prescribing includes indication, dose, quantity, monitoring plan, and review of the prescription drug monitoring program.

Professionalism includes managing conflicts of interest, maintaining scope of practice, and avoiding financial incentives that distort clinical decisions.