• Acute & chronic pain differ in their neurological processing, impact, treatment

• Acute – short duration, subsequent healing

• Chronic long duration with underlying cause – can be chronic malignant with cancer or chronic benign with no disease

• Nociceptors are activated, cause autonomic (sympathetic) and emotional response and behaviors

• Pain stimuli produces physiological & psychic arousal, responses, and either precise localization or chronic pain

• Sharp pain – activates lightly myelinated fibers

• Tissue damage, inflammation activates unmyelinated fibers

• Initial pain, with glutamate as the transmitter, causes primary hyperalgesia, then NO is released that causes secondary hyperalgesia (hurts more)

• Pain pathway includes mesencephalon where impulses are sent to the hypothalamus, limbic system, and cortex for endocrine, autonomic, emotional components and can stimulate the analgesia pathway

• Narcotics cause analgesia by binding to endorphin receptors of the analgesia pathway, that stimulate fibers to release transmitters that inhibit pain signals

• Referred pain and phantom pain are results of pain perception

• Referred pain – pain from internal organs that is perceived from the skin or muscles, because of the dermatome of incoming signal

• Phantom pain after amputation

• Pain from cancer is variable in nature & pathology, from tumor mass with compression, distention, occlusion

• Somatic pain – tissue damaging

• Neuropathic pain – altered neural processing

• Peripheral analgesics inhibit prostaglandin production, by blocking the cyclooxygenase pathway, which raises pain threshold and reduces pain perception

• Narcotics act centrally, bind to receptors in spinal cord, brain stem, cerebrum that endorphins bind to and can also produce constipation, nausea, euphoria

• Use can lead to tolerance (decreased effect)

• Nonmedical techniques can ameliorate pain, includes counterstimulation with accupuncture, electric stimulation, ultrasound

• Headaches can be symptomatic of underlying pathology, and headache syndromes can produce significant disability

• Pain sensitive structures of the head are the venous sinuses and veins, dura mater at the base of the brain, meningeal arteries, and subarachnoid space

• Nerves involved are the trigeminal, vagus, and upper cervical nerves

• Eye, ear, sinuses also sensitive

• Headache types:• Tension – from muscle

tension• Migraine headaches – one

side of the head - accompanied by nausea and vomiting, arteriolar constriction, decreased cerebral blood flow – classic has prodrome, common doesn’t, complicated includes numbness or TIA like symptoms

• Cluster – occur in a cluster of time, similar to migraine pain

• Severe traumatic injury results from burns or mechanical injury, producing wounds

• Abrasion – removal of epidermis, usually minor

• Contusion – bruise, damage to small blood vessels with blood loss into tissue spaces, surface unbroken

• Hematoma – focal pooling of blood in tissue

• Laceration – tear of skin or organ surface

• Bone fractures – incomplete, greenstick from bending, simple with only 2 fragments, comminuted with many fragments, through skin is compound, depressed in skull, pathological because of weakness

• Responses help to maintain blood flow & metabolic support with traumatic injury

• Craniocerebral trauma is serious because the brain is delicate, secondary brain injury from local infarcts, hydrocephalus, hypoxia 2ndary to initial injury

• Concussion – period of lost or altered consciousness from brain injury, usually caused by torsion of cerebrum around the brain stem, reversible interruption of function, severe concussions result in coma

• Coup-contrecoup injury causes edema, hemorrahge, laceration

• Hematoma effects are determined by vessels involved & location relative to meninges

• Epidural hematoma – arterial blood outside of dura that causes pressure

• Subdural – from bridging vein, slow development, also expands

• Closed head injury – no breach of vasculature

• spinal cord trauma is linked to vertebral trauma

• Most vulnerable are cervical vertebrae and upper lumbar

• Spinal shock usually is 1st response – loss of conscious movement, sensation, reflexes from initial trauma

• Thoracic cage trauma can disrupt respiratory movements, lacerate lungs or heart

• Flail chest with rib fractures• Pneumothorax with opening into

pleural spaces – open-sucking, vs tension

• Heart & great vessels can have contusions, dysrhythmia, bleeding with trauma, tamponade

• Abdominal trauma can cause contusion, laceration, rupture of viscera, penetration cause hemorrhage and infection

• Spleen is especially vulnerable, can cause bleeding

• Evisceration – abdominal organs escape from the abdomen

• Peritonitis caused by spilling of secretions and contents, infection

• Athletes have trauma of limbs

• Ligament tears are sprains

• Avulsion – ligament pulls bone off

• Subluxation – dislocation of joint

• Rupture of muscles from excessive load

• Thermal injuries results from heat delivery faster than the skin can dissipate it, classified on depth of damage

• Burns cause fluid loss, infection because of the loss of the barrier

• 1st degree – epidermis• 2nd degree – epidermis & part

of dermis• 3rd degree (full thickness) –

through dermis to subcutaneous tissue

• Smoke inhalation – systemic hypoxia & acidosis, toxic components that enter blood, damage alveolar surfaces – exudate forms, surfactant is inactivated