2024 Furstein Pain II PDF

Pathophysiology of Pain (part deux) J a m i e Furstein, PhD, DNAP, CRNA, CPNP-AC, FAANA How about a quick review… Furstein DNAP 737 2024 Anatomy of Pain Somatosensory System Peripheral Nervo...

Pathophysiology of Pain (part deux) J a m i e Furstein, PhD, DNAP, CRNA, CPNP-AC, FAANA How about a quick review… Furstein DNAP 737 2024 Anatomy of Pain Somatosensory System Peripheral Nervous Spinal Cord Brain System Ascending & Afferent neurons, Somatosensory descending A-delta & C fibers cortex, thalamus pathways Furstein DNAP 737 2024 First-Order Neurons Furstein DNAP 737 2024 Axons Furstein DNAP 737 2024 Furstein DNAP 737 2024 Rexed’s Laminae Furstein DNAP 737 2024 Ascending Pathways Furstein DNAP 737 2024 Periaqueductal Gray Matter Located around the cerebral aqueduct within the tegmentum of the midbrain Initiates pathway for pain inhibition Releases both enkelphalin & GABA Furstein DNAP 737 2024 Furstein DNAP 737 2024 Third-Order Neurons Send fibers to areas of the postcentral gyrus of the parietal cortex & superior wall of the Sylvian fissure Furstein DNAP 737 2024 Furstein DNAP 737 2024 Common Pain Terms Allodynia Perception of an ordinarily non-noxious stimulus a s pain Analgesia Absence of pain perception Anesthesia Absence of all sensation Anesthesia dolorosa Pain in an area that lacks sensation Furstein DNAP 737 2024 Common Pain Terms Dysesthesia Unpleasant or abnormal sensation with or without a stimulus Hypoalgesia Diminished response to noxious stimulation Hyperalgesia Increased response to noxious stimulation Hyperesthesia Increased response to mild stimulation Furstein DNAP 737 2024 Common Pain Terms Hyperapthia Presence of hyperesthesia, allodynia, and hyperalgesia Hypoesthesia Reduced cutaneous sensation Neuralgia Pain in the distribution of a nerve or a group of nerves Paresthesia Abnormal sensation perceived without an apparent stimulus Radiculopathy Functional abnormality of one or more nerve roots Furstein DNAP 737 2024 Classification of Pain Furstein DNAP 737 2024 Classification of Pain Etiology of pain Not all pain is equal Need to consider the anticipated tissue damage secondary to a given procedure PROSPECT initiative (Procedure Specific Postoperative Pain Management) Extent of tissue damage Type of tissue damage (bony vs. soft tissue damage) Furstein DNAP 737 2024 Classification of Pain Classification based on duration of pain: Acute Pain Chronic Pain Recurrent acute pain Ongoing time-limited pain Chronic nonmalignant pain Chronic intractable pain Furstein DNAP 737 2024 Classification of Pain Classification based on mechanism of pain: Nociceptive pain Somatic pain Visceral pain Neuropathic pain Psychogenic pain Furstein DNAP 737 2024 Duration: Acute Pain Serves a s a warning that something is wrong May be mild or severe May last a moment or months Typically does not last longer than 6 months May lead to chronic pain in a s little a s 3 months if unrelieved Furstein DNAP 737 2024 Duration: Acute Pain Typically associated with a neuroendocrine stress that is proportional to intensity Involves 4 physiological processes: Transduction Transmission Modulation Perception Furstein DNAP 737 2024 Predictors of Acute Pain Age-based differences: Age ≥ 5 years of age Gender-based differences: In children, females have a heightened pain response and higher levels of reported pain a s compared with males Furstein DNAP 737 2024 Predictors of Acute Pain Ethnicity: Caucasians report higher pain scores than non-Caucasians and may require more analgesics to control their pain Correctable behaviors leading to increased incidence of pediatric pain: Failure to document pain assessment High prevalence of PRN analgesic dosing Furstein DNAP 737 2024 Duration: Chronic Pain The purpose of chronic pain is poorly understood Pain that persists even though the injury has healed Not often associated with an identifiable cause Often unresponsive to conventional treatment Furstein DNAP 737 2024 Duration: Chronic Pain Common types of chronic pain seen in adult patients: Lower back pain Neuralgias Reflex sympathetic dystrophies Hyperesthesia Myofascial pain syndrome Cancer Chronic postoperative pain Furstein DNAP 737 2024 Chronic Pain Recurrent Acute Pain Characterized by relatively well-defined episodes of interspersed with pain-free periods (migraine) Ongoing Time-Limited Pain Identified by a defined time period (cancer pain that subsides with control of the disease) Chronic Nonmalignant Pain Non-life-threatening pain that persists beyond the expected time for healing (chronic lower back pain) Chronic Intractable Pain Characterized by the person’s ability to cope with pain (cope well vs. physical/social/psychological disability secondary to the pain) Furstein DNAP 737 2024 Duration: Chronic Pain 20-35% of children and adolescents are affected by chronic pain worldwide Chronic pain often includes both persistent and recurrent pain in children with underlying heath conditions Inflammatory bowel disease Sickle cell disease Juvenile idiopathic arthritis Pain can also be the primary disorder Primary headaches Centrally mediated abdominal pain Musculoskeletal pain Complex regional pain syndrome Furstein DNAP 737 2024 Predictors of Chronic Pain Paucity of literature exploring chronic postsurgical pain in children It has been offered that factors predicting CPSP in children and/or adolescents differ from those that predict the maintenance of adult chronic pain Adults: Patient-related factors, such a s APSP intensity, often reported to predict the development of CPSP Children: Pain unpleasantness, not pain intensity, reported to predict the development of CPSP Factors that predict development of pediatric CPSP differ from those that predict its persistence: Development: Pain unpleasantness Persistence: Anxiety sensitivity Furstein DNAP 737 2024 Mechanism: Nociceptive Somatic nociceptive pain Superficial somatic pain: Due to input arising from the skin, subcutaneous tissues and mucous membranes Well localized Sharp, pricking, throbbing, burning Deep somatic pain: Arises from the muscles, tendons, joints, or bones Poorly localized, however, the intensity and duration of the stimulus affect the degree of localization Dull, aching quality Furstein DNAP 737 2024 Mechanism: Nociceptive Visceral nociceptive pain Arises from the body organs Typically presents a s dull and poorly localized due to the low concentration of nociceptors Viscera is sensitive to stretching, inflammation, and ischemia (generally insensitive to surgical incision and temperature extremes) Visceral pain leads to nausea, vomiting, hypotension, and generalized restlessness Often radiates or is referred Furstein DNAP 737 2024 Mechanism: Nociceptive Visceral nociceptive pain Due to disease process, abnormal function of an internal organ or its covering Four subtypes : True localized visceral pain Localized parietal pain Referred visceral pain Referred parietal pain Furstein DNAP 737 2024 Visceral vs. Parietal Pain True visceral pain Dull Diffuse Usually midline Frequently associated with either abnormal sympathetic or parasympathetic activity causing nausea, vomiting, sweating, BP changes, HR changes Parietal pain Sharp Localized to the area around the organ or referred to a distant site Furstein DNAP 737 2024 Referred Pain Furstein DNAP 737 2024 Referred Pain Two mechanisms of referred pain: 1. Dermatome Rule When pain is referred, it is usually to a structure that developed from the same embryonic segment or dermatome a s the structure in which the pain originated from (the heart & the inner aspect of the left arm) 2. Convergence Theory Convergence of somatic and visceral pain fibers on second-order neurons in the dorsal horn Furstein DNAP 737 2024 Referred Pain Convergence Projection Theory Convergence Facilitation Theory Axon of the afferent somatic nerve enters Nociceptive input from deeper structures the s ame segment and terminates on the leads to the alterations in the resting same cell where axon of the sympathetic activity of second-order neurons, thereby nerve terminates increasing or facilitating the transmission of painful signals Two different neurons converging on same second-order neuron Furstein DNAP 737 2024 Mechanism: Neuropathic Pain Changes in the nervous system that leads to sustained pain even after the injury heals Nerve fibers that are damaged, dysfunctional, or injured send incorrect signals Increased sensitivity of the skin that may be described a s burning or feeling of electricity Furstein DNAP 737 2024 Mechanism: Neuropathic Pain In adults, often associated with trauma and/or disease: Diabetic neuropathy Trigeminal neuralgia Post-herpetic neuralgia (shingles) Post-stroke pain Complex regional pain syndrome HIV Furstein DNAP 737 2024 Mechanism: Neuropathic Pain Pediatric neuropathic pain increasingly recognized and can be due to a variety of reasons: Complex regional pain syndrome (CRPS) Phantom limb pain Spinal cord injury Trauma Postoperative neuropathic pain Autoimmune or degenerative neuropathy Cancer and/or cancer treatment Furstein DNAP 737 2024 Mechanism: Neuropathic Pain Furstein DNAP 737 2024 Mechanism: Inflammatory Pain Result of activation and sensitization of the nociceptive pain pathway by a variety of mediators released at a site of tissue inflammation (example: appendicitis) Upon injury or activation, inflammatory mediators are released by the damaged cells causing vessels to dilate and become porous, allowing immune cells to p a s s from the blood into the tissue. Neutrophils engulf and kill invading microbes and release more inflammatory cytokines amplifying the response. When cellular damage occurs near a nerve cell, inflammatory signals can trigger nociceptors Furstein DNAP 737 2024 Mechanism: Inflammatory Pain Furstein DNAP 737 2024 Furstein DNAP 737 2024 Furstein DNAP 737 2024 Mechanism: Psychogenic Pain Most patients with chronic pain have some degree of psychological disturbance which may modulate their experience of pain (anxiety, depression, difficulty coping) Pain may be experienced in the absence of any diagnosed physiologic event or cause and psychological problems may be the primary cause of pain More often, there is a physical problem but the psychological cause for the pain is believed to be the major cause for the pain Most patients with pain that appears to be determined primarily by psychological processes are hurting just like those who have pain associated with a clear injury to the body Furstein DNAP 737 2024 Associated Emotional Disorders Somatization disorder: Physical symptoms of a medical condition that cannot be explained, resulting in involuntary distress and physical impairment Conversion disorder: Symptoms of voluntary motor or sensory deficits that suggest a medical condition Hypochondriasis: Prolonged preoccupation with the fear of having a serious illness despite reassuring medical evaluation Malingering: Intentional production of physical of psychological symptoms that is motivated by external incentives Substance-related disorders: Habitual misuse of prescribed or illicit substances Furstein DNAP 737 2024 Mechanism: Central Pain Pain secondary to a lesion in the brain that may spontaneously produce high frequency bursts of impulses which are perceived a s pain May be secondary to a stroke, vascular lesion, tumor, multiple sclerosis, epilepsy, Parkinson’s disease, trauma, or inflammation Pain is typically constant, may be moderate to severe in intensity, and is often made worse by touch, movement, emotions, and temperature changes, usually cold temperatures Furstein DNAP 737 2024 Trivia Time pain is secondary to changes in the nervous system that leads to sustained pain even after the injury is healed. Nociceptive Neuropathic Psychogenic Central Furstein DNAP 737 2024 Trivia Time Chronic pain that is identified by a defined time period is referred to a s. Recurrent acute pain Ongoing time-limited pain Chronic nonmalignant pain Chronic intractable pain Furstein DNAP 737 2024 And yet another way to view pain… Furstein DNAP 737 2024 Components of Pain 1. Nociception 2. Perception of Pain 3. Suffering 4. Pain behaviors Furstein DNAP 737 2024 Components of Pain: Nociception Nociception (derived from the Latin term “noci” for harm or injury) is used to describe the neural response to traumatic or noxious stimuli All nociception produces pain, but not all pain results from from nociception Interplay exists between objective, emotional and psychological components of pain Furstein DNAP 737 2024 Components of Pain: Perception The perception of pain refers to how one processes and reacts to physiological stimuli This process begins in the dorsal horn of the spinal cord and involves the entire spinal cord and brain Pain can be triggered by the anticipation of potential pain, not just actual tissue damage Furstein DNAP 737 2024 Components of Pain: Suffering Suffering is a negative affective response generated in the brain Connotes enduring an unpleasant and/or inconvenient experience It is an overwhelming state of distress that is both personal and subjective Often used erroneously a s a synonym for pain Furstein DNAP 737 2024 Components of Pain: Pain Behaviors Really the focus of most of our commonly employed assessment strategies Behaviors can be scaled or categorized Pain behaviors can be: Verbal (e.g. verbal descriptions of the intensity, location, and quality of pain; vocalizations of distress; moaning, or complaining) Nonverbal (e.g. withdrawing from activities, taking pain medication, or pain related body postures or facial expressions) Furstein DNAP 737 2024 Furstein DNAP 737 2024 Physiologic Effects of Pain Furstein DNAP 737 2024 Physiologic Effects of Pain Cardiovascular: Hypertension Tachycardia Increase SVR Respiratory: Increased total body O2 consumption Increased CO2 production Increase in minute ventilation Abdominal or thoracic incisions can further compromise pulmonary function (guarding) Furstein DNAP 737 2024 Physiologic Effects of Pain GI and Urinary: Decreased urinary and intestinal motility Promotes ileus and urinary retention Hypersecretion of gastric acid Nausea, vomiting, constipation Hematologic: Increased platelet adhesiveness Reduced fibrinolysis Hypercoagulability Furstein DNAP 737 2024 Physiologic Effects of Pain Endocrine: Increased catabolic hormones Decreased anabolic hormones Development of a negative nitrogen balance, carbohydrate intolerance, increased lipolysis Increases in cortisol and stimulation of RAAS leads to sodium and water retention Immune: Predisposes to infection Furstein DNAP 737 2024 Long Term Impact of Pain Plasticity results in alterations in: Neuronal structure Interneuronal connections Quantity/properties of neurotransmitters, receptors, ion channels Leads to sensitization Peripheral: Sensitized nociceptors exhibit a decreased threshold for activation and an increased rate of firing Central: Wind up phenomenon Furstein DNAP 737 2024 Furstein DNAP 737 2024 Multimodal Anesthesia Furstein DNAP 737 2024 Furstein DNAP 737 2024 Intervene at multiple points…. Furstein DNAP 737 2024 Super painful… Questions? Furstein DNAP 737 2024