15 Notes

Card Set Information

15 Notes
2012-04-30 21:00:41

Alterations of Neurologic Function
Show Answers:

  1. Central Nervous System Disorders
    • Motor vehicle crashes are the major cause of traumatic CNS injury. Traumatic injuries to the head are classified as closed-head trauma (blunt) or open-head trauma (penetrating). Closed-head trauma is the more common type of trauma.
    • Different types of focal brain injury include contusion (bruising of the brain), laceration (tearing of brain tissue), extradural hematoma (accumulation of blood above the dura mater), subdural hematoma (blood between the dura mater and arachnoid membrane), intracerebral hematoma (bleeding into the brain), and open-head trauma.
    • Open-head trauma involves a skull fracture with exposure of the cranial vault to the environment. The types of open-head trauma (compound fracture, perforated fracture) are linear, comminuted, compound, and basilar skull fracture (in the cranial vault or at the base of the skull).
    • Diffuse brain injury (diffuse axonal injury [DAI]) results from the effects of head rotation. The brain experiences shearing stresses resulting in axonal damage ranging from concussion to a severe DAI state.
    • Spinal cord injury involves damage to vertebral or neural tissues by compressing tissue, pulling or exerting tension on tissue, or shearing tissues so that they slide into one another.
    • Spinal cord injury may cause spinal shock with cessation of all motor, sensory, reflex, and autonomic functions below any transected area. Loss of motor and sensory function depends on the level of injury.
    • Paralysis of the lower half of the body with both legs involved is called paraplegia. Paralysis involving all four extremities is called quadriplegia.
    • Return of spinal neuron excitability occurs slowly. Reflex activity can return in 1 to 2 weeks in most persons with acute spinal cord injury. A patter of flexion reflexes emerges, involving first the toes, then the feet and legs. Eventually, reflex voiding and bowel elimination appear and mass reflex (flexor spasms accompanied by profuse sweating, piloerection, and automatic bladder emptying) may develop.
    • Degenerative disk disease is an alteration in intervertebral disk tissue and can be related to normal aging.
    • Spondylolysis is a structure defect of the spine with displacement of the vertebra.
    • Spondylolisthesis involves forward slippage of the vertebra and can involve a crack or fracture of the pars interarticularis, usually at the L5-S1 vertebra.
    • Low back pain is pain between the lower rib cage and gluteal muscles and often radiates into the thigh.
    • Most causes of low back pain are unknown; however, some secondary causes are disk prolapsed, tumors, bursitis, synovitis, degenerative joint disease, osteoporosis, fracture, inflammation, and sprain.
    • Herniation of an intervertebral disk is a protrusion of part of the nucleus pulposus. Herniation most commonly affects the lumbosacral disks (L5-S1 and L4-5). The extruded pulposus compresses the nerve root, causing pain that radiates along the sciatic nerve course.
    • Cerebrovascular disease is the most frequently occurring neurologic disorder. Any abnormality of the blood vessels of the brain is referred to as a cerebrovascular disease.
    • Cerebrovascular disease is the most frequently occurring neurologic disorder. Any abnormality of the blood vessels of the brain is referred to as a cerebrovascular disease.
    • Cerebrovascular accidents (strokes syndromes) are classified according to pathophysiology and include global hypoperfusion, ischemic (thrombotic or embolic), hemorrhagic (intracranial hemorrhage).
    • Transient ischemic attacks (TIAs) are temporary decreases in brain blood flow.
    • Intracranial aneurysms result from defects in the vascular wall and are classified on the basis of form and shape. They are often asymptomatic, but the signs vary depending on the location and size of the aneurysm.
    • An arteriovenous malformation (AVM) is a tangled mass of dilated blood vessels. Although sometimes present at birth, AVM exhibits a delayed age of onset.
    • A subarachnoid hemorrhage occurs when blood escapes from defective or injured vasculature into the subarachnoid space. When a vessel tears, blood under pressure is pumped into the subarachnoid space. The blood produces an inflammatory reaction in these tissues.
    • Infection and inflammation of the CNS can be caused by bacteria, viruses, fungi, protozoans and rickettsiae. Bacterial infections are pyogenic or pus producing.
    • .Meningitis (infection of the meninges) is classified as bacterial, aspetic (nonpurulent), or fungal. Bacterial meningitis primarily is an infection of the pia mater and arachnoid and of the fluid of the subarachnoid space. Aseptic meningitis is believed to be limited to the meninges. Fungal meningitis is a chronic, less common type of meningitis.
    • The meningeal vessels become hyperemic, and neutrophils migrate into the subarachnoid space with bacterial meningitis. An inflammatory reaction occurs, and exudate is formed and increases rapidly.
    • Brain abscesses often originate from infections outside the CNS. Organisms gain access to the CNS from adjacent sites or spread along the wall of a vein. A localized inflammatory process develops with exudates formation, thrombosis of vessels, and degenerating leukocytes. After a few days, the infection becomes delimited with a center of pus and a wall of granular tissue.
    • Clinical manifestations of brain abscesses include headache, nuchal rigidity, confusion, drowsiness and sensory and communication deficits. Treatment includes antibiotic therapy and surgical excision or aspiration.
    • Encephalitis is an acute, febrile illness of viral origin with nervous system involvement. The most common encephalitides are caused by arthropod-borne (mosquito-borne) viruses and herpes simplex. Meningeal involvement appears in all encephalitides.
    • Clinical manifestations of encephalitis include fever, delirium, confusion, seizures, abnormal and involuntary movement, and increased intracranial pressure.
    • Herpes encephalitis is treated with antiviral agents. No definitive treatment exists for the other encephalitides.
    • The common neurologic complications of AIDS are HIV encephalopathy, HIV neuropathy, HIV myelopathy, opportunistic infections, cytomegalovirus, parasitic infection, and neoplasms. Pathologically, there may be diffuse CNS involvement, focal pathology, and obstructive hydrocephalus.
    • Multiple sclerosis (MS) is a relatively common degenerative disorder involving CNS myelin. Although the pathogenesis is unknown, the demyelination is thought to result from the immunogenetic-viral cause. A previous viral insult to the nervous system in a genetically susceptible individual yields a subsequent abnormal immune response in the CNS.
    • Amyotrophic lateral sclerosis (ALS) is a degenerative disorder diffusely involving lower and upper motor neurons. The pathogenesis of ALS is not fully known; however, there is lower and upper motor neuron degeneration.
  2. Peripheral Nervous System and Neuromuscular Junction Disorders
    • Radiculopathies are disorders of the roots of spinal cord nerves. The roots may be compressed, inflamed, or torn. Clinical manifestations include local pain or paresthesias in the sensory root distribution. Treatment may involve surgery, antibiotics, steroids, radiation therapy, and chemotherapy.
    • Plexus injuries involve the plexus distal to the spinal roots. Paralysis can occur with complete plexus involvement.
    • Neuropathies are the resulting syndrome when the peripheral nerves are affected. Axon and myelin degeneration may be present. Neuropathies are classified as sensorimotor, sensory, or motor. The neuropathies are characterized by varying degrees of sensory disturbance, paresis, and paralysis. Secondary atrophy may be present.
    • Guillain-Barré syndrome is a demyelinating disorder caused by a humoral and cell-mediated immunologic reaction directed at the peripheral nerves. The clinical manifestations may vary from paresis of the legs to complete quadriplegia, respiratory insufficiency, and autonomic nervous system instability. Plasmapheresis is used during the acute phase and followed by aggressive rehabilitation.
    • Myasthenia gravis is a disorder of voluntary muscles characterized by muscle weakness and fatigability. It is considered an autoimmune disease and is associated with an increased incidence of other autoimmune diseases.
    • Myasthenia gravis results from a defect in nerve impulse transmission at the neuromuscular junction. IgG antibody is secreted against the “self” acetylcholine receptors and blocks the binding of acetylcholine.
    • Primary disorders of muscles with weakness and atrophy are known as myopathies.
  3. Tumors of the Central Nervous System
    • Two main types of tumors occur within the cranium: primary and metastatic. Primary tumors are classified as intracerebral tumors (astrocytomas, oligodendrogliomas, and ependymomas) or extracerebral tumors (meningioma or nerve sheath tumors). Metastatic tumors can be found inside or outside the brain substance.
    • CNS tumors cause local and generalized manifestations. The effects are varied, and local manifestations include seizures, visual disturbances, loss of equilibrium, and cranial nerve dysfunction.
    • Spinal cord tumors are classified as intramedullary tumors (within the neural tissues) or extramedullary tumors (outside the spinal cord). Metastatic spinal cord tumors are usually carcinomas, lymphomas, or myelomas.
    • Extramedullary spinal cord tumors produce dysfunction by compression of adjacent tissue, not by direct invasion. Intramedullary spinal cord tumors produce dysfunction by both invasion and compression.
    • The onset of clinical manifestations of spinal cord tumors is gradual and progressive, suggesting compression. Specific manifestations depend on the location of the tumor; for example, there may be paresis and spasticity of one leg with thoracic tumors, followed by involvement of the opposite leg.