Thursday, November 20, 2014

TETANUS

TETANUS



Facial spasm and risus sardonicus 

DEFINITION:
Tetanus is a life-threatening illness manifested by muscle rigidity and spasms; it is caused by a neurotoxin (tetanospasmin) produced by Clostridium tetani.


PHYSICAL FINDINGS AND CLINICAL PRESENTATION
● Trismus (“lockjaw”)
● Risus sardonicus (“peculiar grin”), characteristic grimace that results from contraction of the facial muscles (Fig.)
● Generalized muscle spasms causing severe pain and, at times, respiratory compromise and death
● Rigid abdominal muscles, fl exed arms, and extended legs
● Autonomic dysfunction several days after onset of illness
● Leading cause of death: fl uctuations in heart rate and blood pressure
● Usually, absence of fever
● Localized tetanus

1. Rigidity of muscles near the injury
2. Weakness as a result of lower motor neuron injury
3. May be self-limited and resolve spontaneously
4. More often progresses to generalized tetanus
5. Cephalic tetanus:
a. May occur with head injuries or chronic otitis with localized ear or mastoid infection with C. tetani
b. Can manifest as cranial nerve dysfunction


CAUSE
● C. tetani is a gram-positive, spore-forming bacillus that resides primarily in the soil.
● Majority of cases are caused by punctures and lacerations.
● Toxin is elaborated from organisms in a contaminated wound.
● Local symptoms are caused by inhibition of neurotransmitter at presynaptic sites.


1. Over the next 2 to 14 days, the toxin travels up the neurons to the CNS, where it acts on inhibitory neurons to prevent neurotransmitter release.
2. Unopposed motor activity results in tonic contractions of muscles.


DIFFERENTIAL DIAGNOSIS
● Strychnine poisoning
● Dystonic reaction caused by neuroleptic agents
● Local infection (dental or masseter muscle) causing trismus
● Severe hypocalcemia
● Hysteria


WORKUP
● Positive wound culture is not helpful in diagnosis.
● Isolation of organism is possible in patients without the illness.


LABORATORY TESTS
● Usually, normal blood counts and chemistries
● Toxicology of serum and urine to rule out strychnine poisoning


TREATMENT
● Monitoring in a hospital ICU: keep surroundings dark and quiet
● Intubation or tracheostomy for severe laryngospasm
● Débridement of wound
● Human tetanus immunoglobulin (HTIg) via IM injection
● Tetanus toxoid (Td) by IM injection at a different site
● Metronidazole or penicillin G IV
● IV diazepam to control muscle spasms
● Neuromuscular blockade if necessary

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