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 1 st 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 1 st degree – epidermis 2 nd degree – epidermis & part of dermis 3 rd 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