Pt 2 nervous system

• Pathophysiology


  The study of the functional changes that accompany a particular syndrome or disease
• Nervous system


  The body's communication network that works to coordinate and organize the functions of all other body systems
• Central nervous system (CNS)


  • The brain and spinal cord, the body's control center
• Peripheral nervous system (PNS)


  • Contains cranial and spinal nerves, provides communication between the CNS and remote body parts
• Neurologic disorders


  • Alzheimer's disease
  • Amyotrophic lateral sclerosis (ALS)
  • Bell's palsy
  • Epilepsy
  • Guillain-Barré syndrome
  • Meningitis
  • Migraine
• Alzheimer's disease (AD)


  A progressive neurodegenerative disease of the brain that accounts for 60% to 80% of all cases of dementia
• Alzheimer's disease


  • Cortical degeneration is most marked in the frontal lobes, but atrophy occurs in all areas of the cortex
• Familial Alzheimer's


  Genes directly cause the disease, these cases are very rare and have been identified in a relatively small number of families
• Sporadic Alzheimer's


  The most common form of the disease, there is no familial connection, but genes may influence the risk of developing the disease
• Factors contributing to Alzheimer's disease

  • Neurochemical factors, such as deficiencies in the neurotransmitters acetylcholine, somatostatin, substance P, and norepinephrine
  • Viral factors such as slow-growing CNS viruses
  • Trauma
  • Genetic factors
• Risk genes for Alzheimer's disease

  • APOE, which are responsible for the production of a protein that transports cholesterol and other fats throughout the body
  • APOE-e4, those who carry at least one type of risk gene are at high risks of developing AD
• Brain tissue of Alzheimer's patients

  • Neurofibrillary tangles formed out of fibrous proteins in the neurons
  • Beta-amyloid plaques (deposits of protein-like substances)
  • Granulovacuolar degeneration of neurons
• Severity of dementia in Alzheimer's

  Directly related to reduction of the amount of the neurotransmitter acetylcholine
• Insidious onset of Alzheimer's disease

  Changes are barely perceptible at first, but they gradually lead to serious problems
• Signs and symptoms of Alzheimer's disease

  • Behavioral changes (early)
  • Irritability, hostility, mood swings (early)
  • Gradual loss of memory, lack of concentration (early)
  • Impaired learning, poor judgment (early)
  • Decline of cognitive function, memory, language (late)
  • Change in food intake (late)
  • Inability to recognize family, lack of environmental awareness, incontinence, inability to function, Urinary incontinence (late)
• Treating Alzheimer's disease


  There is no cure for AD, current drugs can't alter the progressive loss of brain cells
• Cholinesterase inhibitors


  Prevent the breakdown of acetylcholine, a chemical messenger in the brain that's important for memory and other thinking skills
• Many clinical trials are currently under way for the treatment of Alzheimer's disease, including a vaccine that would stimulate the immune system to recognize and attack the beta-amyloid plaques that occur with the disease
• Amyotrophic lateral sclerosis (ALS)


  A progressive neurodegenerative disease that affects nerve cells of the brain and spinal cord
• ALS


  • Motor neurons eventually die and voluntary muscle movement is impacted
  • People may lose the ability to speak, eat, move, and breathe
  • Weakness and muscle atrophy in upper limbs
  • Cognitive function remains normal
• Types of ALS


  • Sporadic (most common, 90-95% of cases)
  • Familial (inherited, 5-10% of cases)
• Possible causes of ALS

  • Gene mutation
  • Chemical imbalance that results in higher than normal levels of glutamate, too much glutamate is toxic to nerve cells
  • Accumulation of abnormal forms of proteins, which destroy nerve cells
  • Autoimmune disorders
• Precipitating factors for acute deterioration in ALS


  Trauma, viral infection, and physical exhaustion
• Bell's palsy


  The most common facial nerve disorder, characterized by inflammation of cranial nerve VII, on one side of the face, in the absence of stroke or other disease
• Bell's palsy


  • The cause is unknown, though 40,000 Americans are diagnosed of it every year
  • Occurrences are not gender specific, with cases distributed evenly between men and women aged 15 to 60 years
• Risk factors for Bell's palsy


  • Pregnant women in the third trimester
  • Early postpartum
  • Older adults
  • People with diabetes or hypothyroidism
• Etiology of Bell's palsy

  Acute demyelination of nerves, the strongest supported cause is reactivation of the herpes simplex virus isoform (HSV-1) and/or herpes zoster virus (HZV)
• Bell's palsy is considered benign and most patients recover within 3 weeks to 6 months
• Epilepsy


  A neurologic disorder where brain activity is abnormal, causing seizures
• Seizures


  • Paroxysmal events associated with abnormal electrical discharges of neurons in the brain
  • May trigger a convulsive movement, an interruption of sensation, an alteration in the level of consciousness, or a combination of these symptoms
• Epilepsy doesn't affect intelligence in most patients
• Possible causes of epilepsy

  • Genetic influences
  • Perinatal injuries
  • Metabolic abnormalities, such as hyponatremia, hypocalcemia, hypoglycemia, and pyridoxine deficiency (vitamin B6)
  • Brain conditions, such as strokes and brain tumors, brain abscess
  • Infections, such as meningitis, encephalitis, or AIDS
  • Traumatic brain injury
  • Ingestion of toxins, such as mercury, lead, or carbon monoxide
  • High fever in young child
• Status epilepticus


  Prolonged, recurrent or continuous seizure without full recovery between episodes, severe hypoxia and acidosis develop, and there may be additional brain damage if the episode persists
• Treatment of epilepsy


  Seeks to reduce the frequency of seizures or prevent their occurrence
• Treatments for epilepsy


  • Antiseizure drug therapy, specific to the type of seizure, to prevent seizures with minimal side effects and drug toxicity
  • Surgical therapy, if drug therapy fails, to prevent the spread of epileptic activity in the brain
• Electroencephalogram is used to confirm the diagnosis of, and classify, seizures
• Guillain-Barré syndrome (GBS)


  A rapidly progressing acute, autoimmune process occurring a few days to weeks following a viral or bacterial infection, associated with segmented demyelination of peripheral nerves
• Guillain-Barré syndrome


  • Occurs equally in both sexes, usually occurring between ages 30 and 50, affects about 1 out of every 100,000 people
• Phases of Guillain-Barré syndrome

  • Acute phase (begins when the first definitive symptom develops and ends 1 to 3 weeks later, when no further deterioration is noted)
  • Plateau phase (lasts for several days to 2 weeks)
  • Recovery phase (can last from 4 months to 3 years, coincides with remyelination and axonal process regrowth)
• Meningitis


  Usually of bacterial origin, early diagnosis is essential