The infective spores of Clostridium tetani are widely distributed in soil and resistant to heat and disinfectants. Disease occurs when toxin forms after organism growth in wounds; it is characterized by acute onset of skeletal muscle rigidity and convulsive spasm.
The toxin affects inhibitory γ-aminobutyric acid and glycine receptors, leading to unopposed contraction and spasm of skeletal muscle. Initial symptoms involve the facial musculature producing trismus (lockjaw) and risus sardonicus (sneering grin). As larger muscles are involved, one may see opisthotonos, arm flexion and abduction, fist clenching against the thorax, abdominal rigidity, and lower extremity extension. Other symptoms include laryngeal spasm resulting in asphyxia, seizures, hyperthermia, hypertension, diaphoresis, and tachycardia. Reflex spasms may be triggered by minimal external stimuli. Fractures, dislocations, and rhabdomyolysis may occur due to forceful sustained muscle contractions.
Management and Disposition
Diagnosis is primarily clinical. Treatment includes airway protection, metronidazole or penicillin, active immunization with tetanus vaccine, tetanus immune globulin, benzodiazepines, and supportive therapy. Wounds should be cleansed and debrided to eliminate further toxin production. Tetanus immune globulin facilitates removal of unbound tetanus toxin but does not affect toxin attached to nerve endings. Recovery of nerve function requires sprouting of new terminals and formation of new synapses, which may take months to occur.
Tetanus. Fatal generalized tetanus in an 8-year-old Haitian child resulting from an infected puncture wound. Severe opisthotonic posturing and rigid jaw clenching are evident. (Photo contributor: Seth W. Wright, MD.)
There are four clinical forms of tetanus: local, cephalic, neonatal, and generalized disease (most common).
Neonatal tetanus occurs in infants born without passive immunity 3 to 21 days after birth. Inoculation usually occurs through infection of the umbilical stump and is common in developing countries.
Magnesium sulfate decreases spasms and cardiovascular instability.
In developed countries, tetanus is primarily a disease of the elderly, diabetics, and inadequately vaccinated immigrants.
Tetanus disease does not always lead to immunity.
Tetanus. Abdominal wall contractions in a 12-year-old Ugandan girl with tetanus. (Photo contributor: Seth W. Wright, MD.)
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Video 21-02: Tetanus
Opisthotonus and risus sardonicus in tetanus. Entry site for tetanus was the right thigh.
Tetanus. Severe facial tetany. The distorted grin and raised eyebrows are known as risus sardonicus. (Photo contributor: Seth W. Wright, MD.)
Neonatal Tetanus. Neonatal tetanus in a 11-day-old infant. Opisthotonic posturing, muscular rigidity, and inability to swallow are seen. (Photo contributor: Seth W. Wright, MD.)