Tetanus

Key Features

Essentials of Diagnosis

• History of wound with possible contamination

• Jaw muscle stiffness ("lock jaw") then spasms (trismus)

• Neck stiffness

• Dysphagia

• Irritability

• Hyperreflexia

• Finally, painful convulsions precipitated by minimal stimuli

General Considerations

• Caused by the neurotoxin tetanospasmin elaborated by Clostridium tetani

• Spores of this organism are ubiquitous in soil. When introduced into a wound, spores may germinate

• Tetanospasmin interferes with neurotransmission at spinal synapses of inhibitory neurons

• Minor stimuli result in uncontrolled spasms, and reflexes are exaggerated

• Incubation period is 5 days to 15 weeks, with the average being 8–12 days

• Most cases occur in unvaccinated individuals

• While puncture wounds are particularly prone to causing tetanus, any wound, including bites or decubiti, may become infected by C tetani

• Persons at risk

  • Older adults

  • Migrant workers

  • Newborns

  • Injection drug users, who may acquire the disease through subcutaneous injections

Clinical Findings

Symptoms and Signs

• The first symptom may be pain and tingling at the site of inoculation, followed by spasticity of the muscles nearby

• Other early signs

  • Stiffness of the jaw

  • Neck stiffness

  • Dysphagia

  • Irritability

• Hyperreflexia develops later, with spasms of the jaw muscles (trismus) or facial muscles and rigidity and spasm of the muscles of the abdomen, neck, and back

• Painful tonic convulsions precipitated by minor stimuli are common

• Spasms of the glottis and respiratory muscles may cause acute asphyxia

• The patient is awake and alert throughout the illness. The sensory examination is normal. The temperature is normal or only slightly elevated

• Urinary retention and constipation may result from spasm of the sphincters

• Respiratory arrest and cardiac failure are late, life-threatening events

Differential Diagnosis

• Meningitis

• Rabies

• Tetany due to hypocalcemia

• Strychnine poisoning

• Neuroleptic malignant syndrome

• Trismus due to peritonsillar abscess, or use of phenothiazines

Diagnosis

• The diagnosis is made clinically

Treatment

Medications

• Human tetanus immune globulin, 500 units, is given intramuscularly within the first 24 hours of presentation

• Table 33–2 provides a guide to prophylactic management

• Debridement of wounds should be undertaken if implicated as the source

• Metronidazole 7.5 mg/kg administered intravenously or orally every 6 hours (maximum 4 g daily) is preferred and should be administered to all patients

• Penicillin, 20 million units intravenously daily in divided doses, is an alternative