ABR Pain Medicine key terms

A specialized peripheral nerve ending that converts noxious mechanical, thermal, or chemical stimuli into electrical signals. It responds only to intensities that threaten or damage tissue, not to ordinary touch.

Thinly myelinated primary afferent axons that conduct impulses rapidly and carry sharp, well-localized first pain. They terminate mainly in laminae I and V of the dorsal horn and are blocked by local anesthetics.

Unmyelinated, slow-conducting primary afferents that signal dull, burning, poorly localized pain and respond to inflammatory chemicals. They synapse chiefly in the superficial laminae of the dorsal horn.

The ascending pathway in which second-order neurons cross the midline and travel in the anterolateral cord to the thalamus. It carries nociceptive and thermal information from the opposite side of the body.

A dorsal horn neuron that responds to both innocuous and noxious input, firing faster as stimulus intensity rises. Such cells help explain referred pain and central amplification of nociceptive signals.

An activity-dependent increase in spinal and brain excitability after repeated nociceptive input, producing hyperalgesia, allodynia, and enlarged receptive fields. It involves altered synaptic strength, receptor trafficking, and glial activation.

Lowered threshold and heightened responsiveness of nociceptor terminals caused by inflammatory mediators such as prostaglandins, bradykinin, and nerve growth factor. It produces primary hyperalgesia at the site of injury.

Brainstem and cortical pathways, including the periaqueductal gray and rostral ventromedial medulla, that inhibit or facilitate spinal pain transmission. Opioids and stress-related analgesia act partly through this system.

An ion channel that admits calcium when glutamate binds; its upregulation contributes to central sensitization and opioid tolerance. Antagonists such as ketamine can reduce hyperalgesia and wind-up.

A G protein-coupled receptor mediating the analgesic, euphoric, and respiratory-depressant effects of opioids. Activation lowers cyclic AMP and opens potassium channels, reducing neuronal excitability and transmitter release.

A disorder after injury marked by disproportionate limb pain, swelling, skin color and temperature changes, and motor or sensory deficits. Mechanisms include central and autonomic dysregulation, though the exact cause remains debated.

An eleven-point self-report scale from 0 for no pain to 10 for the worst pain imaginable. It is quick and widely used but depends on the patient's ability to translate pain into a number.

A 100-mm line anchored with no pain and worst pain imaginable; the patient marks intensity and the distance is measured. It offers continuous scaling but requires vision, dexterity, and abstract thinking.

A brief clinician-administered screening tool for neuropathic pain that combines a symptom interview with bedside tests such as brushing, pinprick, and cold. A score of four or more suggests neuropathic pain.

A set of eight non-organic examination findings, such as superficial tenderness, overreaction, and regional weakness, that suggest psychosocial distress. They should prompt broader assessment, never a label of malingering.

A 13-item self-report measuring rumination, magnification, and helplessness about pain. Higher scores predict greater disability and poorer response to treatment, making it useful for stratification.

Combining drugs with different mechanisms, such as acetaminophen, nonsteroidal anti-inflammatory drugs, local anesthetics, and opioids, to improve comfort while lowering individual doses and side effects.

A pharmacologic adaptation in which repeated opioid exposure requires higher doses for the same effect. It is distinct from addiction and from physical dependence, and it develops over days to weeks.

Paradoxically increased pain sensitivity during opioid therapy, often with spreading or diffuse pain that differs from the original complaint. Recognition may justify dose reduction or opioid rotation instead of dose escalation.

The dose of one analgesic expected to produce roughly the same effect as another, used to guide safe switching. Published tables are approximations and require reduction for incomplete cross-tolerance.

A partial mu agonist with high receptor affinity and ceiling effects on respiratory depression. Transdermal and buccal formulations treat chronic pain, and it is also used for opioid use disorder.

A synthetic mu agonist that also blocks NMDA receptors and inhibits serotonin and norepinephrine reuptake. Variable half-life and QT prolongation risk demand cautious titration and electrocardiographic monitoring.

Drugs such as gabapentin and pregabalin that bind the alpha-2-delta subunit of voltage-gated calcium channels and reduce excitatory transmitter release. They treat neuropathic pain but cause sedation, edema, and misuse potential.

Older antidepressants such as amitriptyline and nortriptyline that block norepinephrine and serotonin reuptake and sodium channels. Low doses relieve neuropathic pain, but anticholinergic and cardiac effects limit use in older adults.

A serotonin-norepinephrine reuptake inhibitor approved for diabetic peripheral neuropathic pain and chronic musculoskeletal pain. It also treats depression and anxiety, which commonly accompany persistent pain.

An opioid antagonist that rapidly reverses respiratory depression and sedation from overdose. Because its duration is short, patients need observation or a continuous infusion after reversal.

Delivery of corticosteroid, often mixed with local anesthetic, into the epidural space to ease radicular pain from disc herniation or stenosis. Relief is usually temporary and repeat dosing is limited.

An epidural technique that places medication near a specific spinal nerve root through the intervertebral foramen. It is more targeted than interlaminar injection but carries a small risk of vascular injury.

Injection of local anesthetic around the medial branches of dorsal rami that supply facet joints. Relief from two diagnostic blocks supports radiofrequency denervation of those nerves.

Heat generated by alternating current coagulates nociceptive nerve fibers, usually medial branches, to provide longer-lasting relief of facet-mediated pain. Correct placement spares motor fibers.

Implanted electrodes deliver electrical pulses to the dorsal columns to modulate pain transmission, mainly for persistent radicular or neuropathic limb pain. A trial precedes permanent implantation.

Injection of local anesthetic near the stellate ganglion to interrupt sympathetic outflow to the head, neck, and upper limb. It is used for complex regional pain syndrome and sympathetic-maintained pain.

An implanted pump infuses small opioid or local anesthetic doses directly into cerebrospinal fluid, improving analgesia while limiting systemic effects. It requires careful patient selection and ongoing catheter and pump management.

A structured psychological treatment that helps patients identify and change unhelpful thoughts and behaviors related to pain. It builds coping skills and improves function and distress in chronic pain.

A sequential rehabilitation approach using laterality recognition, imagined movement, and mirror therapy to treat chronic limb pain and complex regional pain syndrome. It aims to correct disrupted cortical body maps.

An intensive multidisciplinary program combining physical conditioning, pain education, and psychological support to improve function and return to work. It emphasizes activity and self-management rather than cure.

A state database that tracks controlled substance prescriptions and flags multiple prescribers or early refills. Checking it before starting or continuing opioid therapy is widely recommended.

The process of explaining a procedure's purpose, alternatives, and material risks, then documenting the patient's voluntary agreement. It requires decision-making capacity and a shared discussion.

A framework viewing pain as the product of interacting biological, psychological, and social factors rather than tissue damage alone. It underpins multidisciplinary assessment and treatment planning.