micro chap 19

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micro chap 19
2009-11-20 01:55:59

infectious diseases affecting the nervous system
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  1. -occurs years after an intital measles episode
    -seems to be caused by direct viral invasion of neural tissue
    measles virus: subacute sclerosing panencephalitis (SSPE)
  2. -transmissible spongiform encephalopathies (TSEs): neurodegenerative diseases with long incubation periods but rapid progression once they begin
    -Human TSEs
    *Creutzfeldt-Jakob disease (CJD)
    *Gerstmann-Strussler-Scheinker disease
    *fatal familial insomnia
  3. -slow, progressive zoonotic disease
    -characterized by fatal encephalitis
    -average incubation time: 1-2 months or more
    -prodromal phase begins with fever, nausea, vomiting, headache, fatigue, and other nonspecific symptoms
    -two forms (both forms progress to the coma phase, resulting in death)
  4. -periods of agitation, disorientation, seizures, and twitching
    -spasms in the neck and pharyngeal muscles lead to hydrophobia
    furious rabies
  5. -patient is not hyperactive but is paralyzed, disoriented and stuporous
    dumb rabies
  6. -acute enteroviral infection of the spinal cord
    -can cause neuromuscular paralysis
    -often affects small children
    -most infections are contained as short-term, mild viremia
    -some develop mild nonspecific symptoms of fever, headache, nausea, sore throat, and myalgia
    -then spreads along specific pathways in the spinal cord and brain
  7. poliomyelitis

    -the virus infiltrates the motor neurons of the anterior horn of the spinal cord
  8. poliomyelitis

    -invasion but not destruction of nervous tissue
  9. poliomyelitis

    -various degrees of flaccid paralysis
  10. poliomyelitis

    -bulbar poliomyelitis
    rare cases
  11. -also known as lockjaw
    -Clostridium tetani
    -gram-positive, spore-forming rod
    -releases a powerful neurotoxin, tetanospasmin, that binds to target sites on peripheral motor neurons, spinal cord and brain, and in the sympathetic nervous system
    -toxin blocks the inhibition of muscle contraction
    -results in spastic paralysis
    -first symptoms: clenching of the jaw, followed in succession by extreme arching of the back, flexion of the arms, and extension of the legs
    -Risus sardonicus
  12. -intoxication associated with eating poorly perserved foods
    -can also occur as a true infection
    -three major forms
    -symptoms: double vision, difficulty in swallowing, dizziness; later symptoms include descending muscular paralysis and respiratory compromise
    -Clostridium botulinum (spore forming anaerobe, releases an endotoxin- botox)
  13. ingestion of preformed toxin
    food-borne botulism
  14. entrance of botulinum toxin into the bloodstream
    infant botulism and wound botulism
  15. -Trypanosoma brucei
    -also called trypanpsomiasis
    -affects the lymphatics and areas surrounding blood vessels
    -usually a long asymptomatic period precedes onset of symptoms
    -symptoms include intermittent fever, enlarged spleen, swollen lymph nodes, and joint pain
    -central nervous system is affected with personality and behavioral changes that progress to lassitude and sleep disturbances
    African sleeping sickness