Pain, Temperature, Sleep, and Sensory Function Pain one of the bodys most important adaptive mechanisms an unpleasant sensory or emotional experience associated with actual or potential tissue damage, or described in terms of such damage Amer. Pain Society whatever the experiencing person says it is, existing whenever he says it does - Margo McCaffrey one person cannot judge the perception of pain in another culture influences a peoples response to pain pain occurs with tissue damage, there is no correlation between the amount of tissue damage and the degree of pain experienced a clear distinction among pain types may not be always possible Two major types: Stimuli Table Nociceptive A. somatic-joints, muscle, skin B. visceral-organs(tumors/obstruction) 2. Neuropathic A. Central-central or peripheral NS B. Peripheral-neuropathies(DM/GB disease) Neuroanatomy of Pain Nociception 1) Afferent pathways peripheral (PNS) spinal gate (dorsal horn) higher centers (CNS) 2) Interpretive centers brain stem, midbrain, diencephalon and cerebral cortex 3) Efferent pathways CNS dorsal horn of spinal cord (modulate pain) Nociceptors free nerve ending Free nerve endings in skin, muscle, joints, arteries, and the viscera that respond to chemical, mechanical, and thermal stimuli Can detect a wide range of stimuli A delta fibers: touch, vibration, thermal & pain Unmyelinated C polymodal fibers: pain Skin and its accessory structures structure function growth and repair development aging disorders 1.Transduction 2.Transmission 3.Perception 4.Modulation Sensitizing substsnces Prostaglandins, bradykinin, serotonin, substance P, histamine Action potential wave of depolarization Tissue damage Spinal cord Brain stem & thalamus cortex conscious experience of pain inhibition of nociceptive impulses Brain stem * Spinal cord *Endorphins, serotonin, NE Gate Control Theory Melzack & Wall 1965 Small c fibers pain( diffuse,burning,aching) Large A fibers touch, vibration or thermal stimulation(localized,sharp)-pain Inhibitory interneurons dorsal horn balance between c fibers and non- nocieptive A fibers(touch,vibration,thermal) Neuromodulation of Pain Located in pathways of nervous system Hypothalamus, pituitary gland, spinal cord, brain Triggered by tissue injury/inflammation Excitatory Substance P, glutamate, somatostatin Inhibitory GABA, serotonin, norepinephrine, endorphins OLDCART Oonset Llocation Dduration Ccharacteristics (sharp,crampy,burning,dull) Aaggravating/alleviating/associated Rradiation Ttreatment Clinical Descriptions of Pain Acute immediate, harmful alert, acute anxiety: tissue damage, self-limiting, ends with healing Somatic superficial, sharp, well localized dull, aching, poorly localized, nausea and vomiting Visceral internal organs, abdomen or skeleton, poorly localized ( # receptors) nausea and vomiting, hypotension, restlessness and shock generalized stress response physiologic signs associated with pain low/moderate/superficial sympathetic nervous system HR, BP, RR, muscle tension, dilating pupils, diaphoresis Severe or deep pain Parasympathetic nervous system Pallor, muscle tension, HR, irreg RR, N/V, weakness & exhaustion Acute Referred Area distant from the point of origin, same spinal segment as the actual site of pain, more receptors in the skin Chronic Pain-Neuropathic lasting 3 to 6 months Injury to the nervous system Persistent (low back pain) or intermittent (migraines) Produces significant behavior of psychologic changes Types Myofascial muscle, fascia Chronic postoperative pain Cancer pain (Chapter 10) Neuropathic Pain increased sensitivity to painful stimuli do to: abnormal processing of sensory input Chronic 1.Peripheral pain nerve entrapment or diabetic neuropathy 2.Central lesion/dysfunction in the CNS phantom limb Aging and Pai n Increase in pain threshold Peripheral neuropathies Skin thickness changes Decrease pain tolerance Alteration in metabolism of drugs and metabolites Temperature Regulation heat production heat conservation heat loss Extremities are cooler than the core Daily fluctuation (circadian rhythm) (0.2 0.5 C) Peak at 6:00 p.m. Lowest with sleep Hypothalamic Control : conserve heat Thermoreceptors Peripheral skin Central hypothalamus, cord, abdominal organs 1.Endocrine System TSH-RH Thyroxine adrenal Epinephrine vasoconstriction, glycolysis & metabolic rate heat production 2.Sympathetic Nervous System skeletal muscle tone Initiates shivering Vasoconstriction 3.Cerebral Cortex voluntary body movement, bundle up, curl in a ball Fever resetting of the hypothalamic thermostat Active heat production and conservation measures a new set point Exogenous pyrogens (endotoxins) Endogenous pyrogens TNF,IL- 6,IF Benefits of Fever Kills many microorganisms serum levels of iron, zinc and copper Needed for metabolism of bacteria Promotes lysosomal breakdown and autodestruction of cells # viral replication lymphocytic transformation and phagocyte motility Augments antiviral interferon production Hyperthermia Not mediated by pyrogens No resetting of the hypothalamic set point 41C (105.8F) nerve damage produces convulsions 43C (109.4F) results in death Forms Heat Cramps fever, pulse, blood pressure Heat Exhaustion dizziness, weakness, nausea, confusion and syncope Heat Stroke core > 40C-104F :cerebral edema, degeneration of the CNS, renal tubular necrosis and death Damage to the CNS,inflammation, increased intracranial pressure or intracranial bleeding Body Temperature> 39 /102.2 degrees central fever +/- bradycardia Resistant to antipyretic therapy Malignant Hyperthermia rare inherited muscle disorder Precipitated by inhaled anesthetics and neuromuscular blocking agents Ca ++ release or Ca ++ uptake with muscle contraction Sustained muscle contraction (O 2 use, lactic acid) Symptoms resemble those of coma with anuria (children and adolescents) Hypothermia Body temperature < 35C Produces Depression of the CNS and respiratory systems, vasoconstriction, in microcirculation, coagulation and ischemic tissue damage Severe ice crystals within the cells rupture and death Sleep temporary state of restful unconsciousness with spontaneous arousal Two stages alternate Rapid eye movement sleep (REM) :dreams Non-REM sleep Stage I-IV REM Sleep 20 25% of sleep time Paradoxic sleep EEG pattern awake very active brain Occurs every 90 minutes beginning after 1-2 hours of sleep Non-REM Sleep 75 80% of sleep time Initiated when inhibitory signals are released from the hypothalamus - parasympathetic tone 4 stages - EEG Sleep Disorders Dyssomnias Insomnia : inability to fall or stay asleep (mild, moderate or severe) Sleep disordered breathing: obstructive sleep apnea syndrome primary hypersomnia (narcolepsy) Disorders of the sleep-wake schedule: jet lag, sleep schedule Sleep Disorders Parasomnias unusual behavior during sleep Sleepwalking, night terrors, rearranging furniture, eating food, violent behavior and restless leg syndrome Visual Dysfunction Ocular movement III, IV, VI CN (Figure ) Strabismus Diplopia (weak or hypertonic muscle) Nystagmus Pedular regular to-and-fro Jerk one phase faster Causes: inner ear, cerebellum, CN, drugs, retinal disease, cervical cord disease Dysfunction of Acuity ability to see objects in sharp detail Glaucoma - intraocular pressure (> mmHg) upon optic nerve death Cataract cloudy or opaque area in ocular lens Age-related macular degeneration loss of vision (risk factors: HTN, cigarettes, DM) Alterations in Refractions Myopia nearsightedness: focus in front of the retina (long eyeball) Hyperopia farsightedness: focus behind retina (fat eyeball) Astigmatism uneven corneal curvature no single retinal focus Auditory Dysfunc tion 5% - 10% population has impaired hearing Conductive change in outer or middle ear impairs conduction Impacted cerumen, foreign bodies, tumors (middle ear, canal), eustachian tube, otitis media Sensorineural impairment of the organ of Corti or its central connections Congenital, noise, aging, meniere's disease, ototoxicity, systemic disease (syphilis, diabetes, others), and neoplasms. Ear Infectio ns Otitis externa Infection of the outer ear Prolonged moisture exposure (swimmers ear) and bacteria Otitis media infants and children Acute pain, fever, inflamed TM with middle ear fluid With effusion fluid in middle ear without symptoms Page 340 Geriatrtic Considerations Olfaction and Taste Olfaction (smell) CN I Taste (gustation) CN VII & IX Strong relationship between taste and smell Sour, salt, sweet, bitter, umami Umami? Olfaction and Taste Dysfunctions Olfactory ( 7 classes) Hyposmia impaired Anosmia loss Hallucinations odors not present Parosmia - abnormal Taste (5 classes) Hypogeusia - taste Ageusia absence of taste Dysgeusia unpleasant flavor Page 341 Somatosensory Function Touch 4 afferent fiber types touch, vibration pressure, stretch, joint position Fusion of intensity, location and duration of stimulus to higher CNS centers Proprioception body position Depends upon inner ear, vision, and receptors in joints and ligaments Proprioceptive Dysfunction Vestibular nystagmus eyeball movement 2 to overstimulation of the semicircular canals Vertigo spinning sensation 2 to inflammation of the semicircular canals Menieres disease