Did you get your Tetanus Shot?

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Name that Sign!  Hint: It’s not a Glasgow Smile
Answer:  Risus Sardonicus.  Caused by spasms of the facial muscles.  Also seen in Wilson’s Diseases and Strychnine poisoning.
TETANUS
  • Caused by Clostridium Tetani, which is present in soil, animal feces
  • Typical presentation of “Stepped on a rusty name” and didn’t get their tdap.
    • Also in IVDU, abdominal surgeries
  • Per CDC, leads to death in 1 in 10 cases, usually in the elderly.
SIGNS AND SYMPTOMS
  • Initial signs are trismus or “lock jaw”- spasms of muscles of mastication
  • If not treated, progresses to sustained muscles of the back:  Opisthotonus
  • By second week, tachycardia, labile HTN, sweating, hyperpyrexia, increased urinary excretion of catecholamines
PATHOPHYSOLOGY
  • Ubiquitous spores in soil and animal feces
  • Introduced into skin as spore-forming, non-invasive state
  • Germinates into toni-producing, vegetative form if oxygen tension is reduced
    • e.g. crushed, devitalized tissue
  • Toxins=Tetanolysin and Tetanospasmin
  • Tetanospasmin does not cross BBB but CAN enter via retrograde intraneuronal transport
  • Acts on motor endplates of skeletal muscle, spinal cord, CNS, and sympathetics
  • Inhibits glycine and GABA
    • In short get sympathetic overactivity and high circulating catecholamines
TREATMENT
  • Admit to ICU
  • Needs intubation if respiratory compromised
    • Succinylcholine for intubation, Vecuronium for longer blockade
  • Minimize environmental stimuli to avoid convulsive spasms
  • Tetanus Immunoglobulin 3K-6K units IM helps locally but not if it is in the CNS
    • Nevertheless, reduces mortality
  • Can give parenteral metronidazole
  • Do NOT give PCN because central acting GABA antagonist which may potentiate tetanospasmin
  • Mag sulfate to help inhibit release of catecholamines/reduce autonomic instability/spasms
  • Midazolam for muscle spasm
SUMMARY
  • Clinical dx- look for autonomic instability, muscle spasms
  • Tx w/ ICU, intubation, Midazolam, Mag sulfate, Flagyl but NO PCN
REFERENCES
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