Pain, Temperature, Sleep, and Sensory Function

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Chapter 13

• Pain, Temperature, Sleep, and Sensory Function

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• 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

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Pain

• 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

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Pain

• a clear distinction among pain types may not be
  always possible
• Two major types Stimuli Table 13-1
• 1.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)

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• Neuroanatomy of Pain
• Nociception
• Afferent pathways peripheral (PNS) ? spinal
  gate (dorsal horn) ? higher centers (CNS)
• Interpretive centers brain stem, midbrain,
  diencephalon and cerebral cortex
• Efferent pathways CNS ? dorsal horn of spinal
  cord (modulate pain)

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• 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

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The Integumentary System

• Skin and its accessory structures
• structure
• function
• growth and repair
• development
• aging
• disorders

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Nociception Pain Transmission

• 1.Transduction
• 2.Transmission
• 3.Perception
• 4.Modulation

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Transduction tissue damage

• Sensitizing substsnces
• Prostaglandins, bradykinin, serotonin, substance
  P, histamine
• Action potential
• wave of depolarization

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Transmission

• Tissue damage
• Spinal cord
• Brain stem thalamus
• cortex

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Perception of Pain

• conscious experience of pain

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Modulation

• inhibition of nociceptive impulses
• Brain stem
• Spinal cord
• Endorphins, serotonin, NE

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• 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)

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• 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

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PAINDescription

• OLDCART
• Oonset
• Llocation
• Dduration
• Ccharacteristics (sharp,crampy,burning,dull)
• Aaggravating/alleviating/associated
• Rradiation
• Ttreatment

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• 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

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Acute Pain

• generalized stress response
• physiologic signs associated with pain
• low/moderate/superf
  icial
• sympathetic nervous system
• HR, BP, RR, muscle tension, dilating
  pupils, diaphoresis

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Acute Pain

• Severe or deep pain
• Parasympathetic nervous system
• Pallor, muscle tension, HR, irreg RR, N/V,
  weakness exhaustion

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• Acute
• Referred
• Area distant from the point of origin, same
  spinal segment as the actual site of pain, more
  receptors in the skin

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Referred Pain
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• 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)

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• 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

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• Aging and Pain
• Increase in pain threshold
• Peripheral neuropathies
• Skin thickness changes
• Decrease pain tolerance
• Alteration in metabolism of drugs and metabolites

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• 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 600 p.m.
• Lowest with sleep

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• 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

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• 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

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• 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

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• 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 gt 40C-104F cerebral edema,
  degeneration of the CNS, renal tubular necrosis
  and death

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Trauma and Temperature

• Damage to the CNS,inflammation, increased
  intracranial pressure or intracranial bleeding
• Body Temperaturegt 39/102.2 degrees
• central fever
• /- bradycardia
• Resistant to antipyretic therapy

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• 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 (?O2 use, ? lactic
  acid)
• Symptoms resemble those of coma with anuria
  (children and adolescents)

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• Hypothermia
• Body temperature lt 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

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• Sleep
• temporary state of restful unconsciousness with
  spontaneous arousal
• Two stages alternate
• Rapid eye movement sleep (REM) dreams
• Non-REM sleep
• Stage I-IV

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• 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

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• Non-REM Sleep
• 75 80 of sleep time
• Initiated when inhibitory signals are released
  from the hypothalamus - ? parasympathetic tone
• 4 stages - EEG

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NREM SleepPET Scan
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REM Sleep PET Scan
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• 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

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• Sleep Disorders
• Parasomnias unusual behavior during sleep
• Sleepwalking, night terrors, rearranging
  furniture, eating food, violent behavior and
  restless leg syndrome

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The Eye
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• Visual Dysfunction
• Ocular movement III, IV, VI CN (Figure 12-22)
• 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

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Strabismus
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• Dysfunction of Acuity
• ability to see objects in sharp detail
• Glaucoma - ? intraocular pressure (gt 12-20 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)

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• 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

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Alterations in Refraction
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LASIK Surgery
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The Ear
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• Auditory Dysfunction
• 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.

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The Ear
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• Ear Infections
• 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

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Aging and Change in Hearing

• Page 340 Geriatrtic Considerations

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• Olfaction and Taste
• Olfaction (smell) CN I
• Taste (gustation) CN VII IX
• Strong relationship between taste and smell
• Sour, salt, sweet, bitter, umami

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Taste Buds Cranial Nerves

• Umami?

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Taste Bud
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• 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

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• 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

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• 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