neuro

• Pain


  A complex experience with dynamic interactions between physical, cognitive, spiritual, emotional and environmental factors

  
• pain is defined as

  
  

  "an unpleasant sensory and emotional experience associated with actual or potential tissue damage"
• Process of Nociception


  1. Transduction

  2. Transmission

  3. Perception

  4. Modulation
• Transduction


  • Activation of Nociceptors (noxious stimuli)
  • Chemical
  • Mechanical
  • Thermal
• Transmission


  • Ad fibers (rapid, sharp, well-localized)
  • C fibers (slow, dull, aching or burning, poorly localized)
  • Ab fibers (modulation)
• Perception and Modulation of Pain

  • Conscious awareness – reticular and limbic systems and cerebral cortex. Interpretation influenced by cultural factors and life experiences.
  • Modulation – inhibitory neuromodulators and endogenous opioids
• Endogenous Opioids

  • Enkephalins
  • Endorphins
  • Dynorphins
  • Endomorphins
  • b Endorphin
• Classification of Pain

  • Nociceptive
  • Neuropathic
  • Idiopathic
  • Referred
  • Acute or Chronic
• Neuropathic Pain


  • Injury or malfunction of the spinal cord and/or peripheral nerves
  • Diabetes and chemotherapy are common causes
  • Burning, tingling, shooting, stinging, pins-and-needles sensation (paresthesia)
  • Difficult to treat
• Temperature


  • Norm 37.0oC, 98.6oF
  • Measurement of core temperature: Pulmonary artery thermistor, Tympanic membrane, Foley, Rectal and oral temperatures, Infrared
• Thermoregulation


  • Mediated by hypothalamus
  • TSH-RH, TSH, thyroxine
  • Circadian rhythm (peaks about 6 pm)
  • Fluctuations with menstrual cycle, sharp rise just before ovulation
• Mechanisms of Heat Production and Loss

  • Heat production: metabolism, muscle contraction (including shivering), chemical thermogenesis
  • Heat loss: radiation, conduction, convection, evaporation; decreased muscle tone, increased ventilation, administration of cool fluids
• Fever


  • Endogenous pyrogens (TNF-a, IL-1, IL-6)
  • Raising body temperature kills many microorganisms, decrease serum levels of iron, zinc and copper (minerals needed for bacterial replication), increasing lysosomal breakdown and auto destruction of cells preventing viral replication, phagocytosis is enhanced
• Hyperthermia


  • At 41oC (105.8 F), nerve damage, coagulation of cell proteins, and seizure can occur in adults
  • At 43oC (109.4 F), death occurs
• Hypothermia


  • At 35oC (95 F), a range of cardiac dysrhythmias occur
  • Atrial fibrillation is most common
  • Associated with a decrease in cardiac output
• Functions of Sleep


  • Conservation of energy
  • Restoration of tissues and growth
  • Thermoregulation
  • Regulation of emotions—sleep deprivation causes emotional disorders like irritability, anxiety, depression
  • Neural maturation
  • Memory and learning—information transfer between cerebral cortex and hippocampus
• Sleep


  Controlled by the suprachiasmatic nucleus (SCN) in the hypothalamus
• • Infants sleep 16-17 hours/day
  • 50% REM sleep; 50-60 minute cycles
• Elderly – total sleep time is decreased with longer sleep latency and poorer quality of sleep; sleep disorders increase the risk of morbidity and mortality
• Changes in the Eye with Aging

  • Cornea > increased astigmatism
  • Anterior chamber > glaucoma
  • Lens > decreased color vision, cataracts
  • Retina > increased minimal amount of light to see an object
• Aging and Changes in Hearing

  • Cochlear hair cell degeneration
  • Loss of auditory neurons
  • Degeneration of conductive membrane of the cochlea
  • Loss of cortical auditory neurons
• Medication Related Changes in Hearing

  • Rapid intravenous injection of a large dose of furosemide > electrolyte imbalance in hair cells, usually transient
  • Gentamycin > auditory nerve damage, possibly permanent
• Changes in Smell and Taste

  • Decline in sensitivity to odors, usually after age 80
  • Decline in olfaction may lead to diminished appetite
  • Inability to smell toxic fumes or gases
  • Higher concentrations of flavors required to stimulate taste
  • Taste may be influenced by decreased secretion of saliva
• Neurological Tools and Assessment


  • LOC, Pupillary Response, Posturing, ICP and CPP
• Level of Consciousness (LOC)

  • Arousal and awareness of self and environment
  • Oriented x3: person, time and place – keep in mind the effects of sleep deprivation among hospitalized
  • Response to painful stimuli: withdraws (or swings at you appropriately), decorticate/decerebrate posturing
• Altered Levels of Consciousness

  • Metabolic
  • Psychogenic
  • Drug induced
• Pupillary Responses


  • Lack or pupil response to light (Indicates a brain-stem lesion (autonomics))
  • "Dolls head" Movement (Brainstem intact)
  • "Fixed" Brainstem NOT intact
• Posturing

  • Decorticate posturing (damage to one or both corticospinal tracts)
  • Decerebrate posturing (upper brain stem damage)
• Intracranial Pressure (ICP)


  • Cranial Cavity: 3 compartments (80% brain tissue, 10% CSF, 10% Blood)
  • Encased in a nonexpendable skull! As pressure builds, brain tissue is subject to serious damage!
• Age Group ICP (mmHg)

  • Adults (supine) 5-15
  • Children 3-7
  • Infants 1.5-6
• Monro-Kellie Hypothesis

  • "Increases in ICP within one compartment can be offset by a decreased volume in another compartment"
  • Compensation is limited by skull
  • Brain is able to compensate the most by compression……but brain compression may lead to rapid injury
• Increased Intracranial Pressure (ICP)

  • Causes: Hemorrhage, Trauma, Infection, Severe hypertension, Brain tumor brain edema
  • Manifestations: Decreased level of consciousness, Lethargy, confusion, stupor, Cellular hypoxia, Brain injury & coma
• Cushing's Reflex


  • Occurs with severe, prolonged increases in ICP
  • Ischemia of vasomotor & cardiovascular centers in the medulla
  • Marked increase in MABP (270 mmHg!)
  • Reflex slowing of heart rate
• Increased ICP Treatment


  • Stop bleeding (trauma, stroke)
  • Remove tumor
  • Osmotic Diuretic (mannitol)
  • Surgical drain, shunt to relieve pressure
• Cerebral Vascular Accident (CVA)


  • Also known as Stroke
  • Major source of mortality (#3)
  • 600,000/year
  • Types: Transient Ischemic Attack (TIA), Ischemic, Hemorrhagic
• Risk Factors for Stroke

  • HTN
  • Tobacco use
  • High salt, fat and caloric diet
  • Excess ETOH
  • Hyperlipidemia
  • Heart disorders (inc clot)
  • Uncontrolled DM
  • Obesity
  • Previous stroke or TIA
  • Cocaine and amphetamines
  • Bleeding D/O
  • Coagulation D/O
  • Vasculitis
  • Arteriovenous malformation
  • Cerebral aneurysm
  • Sickle cell disease
  • Sedentary lifestyle
  • Oral contraceptives
  • Family history of stroke
  • Advancing age
  • African American, Hispanic American and American Indian/Alaska Native
• Transient Ischemic Attack (TIA)


  • Temporary neurologic symptoms (minutes to hours); resolves in about 24 hours
  • Caused by an embolus – body's fibrinolytic system dissolves the clot
  • Imbalance in clot development and dissolution
  • Warning sign!!!
• Thrombus

  • Arise from atherosclerotic plaque
  • Begins with endothelial injury – predisposing factors include free radical injury, hypertension, hyperlipidemia, or elevated glucose levels (such as in diabetes)
• Thrombotic Stroke


  • Arterial occlusion from a formed thrombus: Embolic (Atrial fibrillation), Arteriosclerosis
  • Other contributing factors: Inflammation of cerebral arteries, Inadequate Cerebral Perfusion (Hypotension, Dehydration)
• Embolic

  • Emboli most frequently from intracardiac thrombi in the left heart or valvaular heart disease
  • Common in atrial fibrillation without adequate anticoagulation
  • Ventricular aneurysm following anterior wall myocardial infarction
  • Other causes: fat emboli (long bone fracture), air emoboli