Tetanus

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Tetanus is a life threatening infection caused by Clostridium tetani, a toxin producing anaerobic bacterium that affects the nervous system, leading to muscle rigidity and spasms.

Aetiology

• Caused by Clostridium tetani, a Gram-positive, spore-forming anaerobic bacillus.
• Transmission occurs via contamination of wounds with spores from soil, dust, or animal faeces.
• Spores germinate in anaerobic conditions, releasing tetanospasmin toxin.

Pathophysiology

• Tetanospasmin toxin inhibits inhibitory neurotransmitter release (GABA and glycine) in the central nervous system.
• This leads to unchecked motor neuron activity, resulting in prolonged muscle contraction and spasms.
• Autonomic dysfunction can occur in severe cases.

Risk Factors

• Penetrating injuries contaminated with soil or faeces.
• Chronic wounds, burns, or surgical wounds.
• Intravenous drug use.
• Neonates (neonatal tetanus due to poor umbilical cord hygiene).
• Incomplete or absent tetanus vaccination.

Signs and Symptoms

• Early symptoms:
  • Trismus (lockjaw).
  • Neck stiffness and difficulty swallowing.
  • Generalised muscle rigidity.
• Generalised tetanus:
  • Opisthotonos (arched back due to severe muscle contractions).
  • Intermittent muscle spasms triggered by minor stimuli.
  • Autonomic instability: tachycardia, hypertension, sweating.
• Neonatal tetanus:
  • Poor feeding and irritability in the first two weeks of life.
  • Progression to generalised rigidity and spasms.

Investigations

• Clinical diagnosis: based on characteristic symptoms.
• Wound culture: Clostridium tetani rarely cultured.
• Serum toxin assay: not widely available.
• Electromyography (EMG): may show continuous muscle activity.

Management

1. Immediate Resuscitation:

• Secure airway and provide ventilatory support if needed.
• Control muscle spasms with benzodiazepines (e.g., diazepam, lorazepam).

2. Toxin Neutralisation:

• Administer human tetanus immunoglobulin (TIG) intramuscularly.
• Ensure full tetanus vaccination course is given.

3. Wound Management:

• Surgical debridement of necrotic tissue to remove anaerobic environment.
• Empirical antibiotics (metronidazole or penicillin) to reduce bacterial load.

4. Supportive Care:

• Manage autonomic instability with labetalol or magnesium sulfate.
• Provide IV fluids and nutrition.
• Minimise external stimuli to reduce muscle spasms.

5. Prevention:

• Routine tetanus vaccination with booster doses every 10 years.
• Post exposure prophylaxis with tetanus immunoglobulin and vaccine in high risk wounds.

6. Referral:

• Intensive care: for respiratory support in severe cases.
• Infectious diseases: for management of complicated cases.

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