11.6. Tetanus
- General considerations:
- Approximately one million cases occur annually worldwide
- Twenty five percent (approximately) from occupational injury
- Clostridium tetani:
- Obligate anaerobe
- Requires extrachromosomal DNA (plasmid) for production of tetanospasmin)
- Inhibits release of Ach from the presynaptic terminals
- Retrogradely transported to enter the CNS
- Blocks release of glycine and GABA b from presynaptic terminals
- Toxin transported to both the sensory neurons of the dorsal root ganglia and archenteric neurons
- Clinical features:
- Generalized tetanus
- Rigid masseters ("lock-jaw") at presentation
- Generalized spasms with opisthotonus; no loss of consciousness
- Painful muscles with increased reflexes
- Localized tetanus
- May progress to generalized disease
- Cephalic form:
- Involves the lower cranial nerves
- Facial weakness, dysphagia and rarely ophthalmoplegia
- Source is chronic middle ear infection
- Neonatal variety
- 50% of tetanus infection with an approximate 90% mortality
- Infection of the umbilical stump
- Weakness and inability to suck during the second week of life
- Mechanisms of death are:
- Respiratory
- Autonomic dysregulation
- EMG:
- Continuous and excessive motor unit activity
- Normal nerve conduction studies
- Absent silent period from affected muscles
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