Tetanus

Cover art: Muscle spasms (specifically opisthotonos) in a person with tetanus. Painting by Sir Charles Bell, 1809.

Introduction

Tonic muscular contractions usually commencing at the site of infection, later becoming generalised, involving the entire somatic muscular system.

• Tetanus toxin (2nd M/lethal toxin)
  • Lethal dose: 0.1mg

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Etiology

Clostridium tetani

Gram-positive, anaerobic, motile, non-capsulated organism with peritrichous flagella & terminal spores (Drumstick appearance)

• No prior immunisation or partial immunisation
• Trauma with lacerations, deep wound, crush devitalized tissue, foreign body infections, etc
• Chronic suppurative otitis media (CSOM) with perforation, caries teeth
• Improper sterilisation
• Tattooing, rusted nails, earlobe prick

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Presentation

• Descending paralysis
• Trismus or Lockjaw (Jaw stiffness) (M/C): Spasm of masseter & pterygoids
• Risus sardonicus (smiling facies): Spasm of facial muscles (zygomaticus major)
• Spasm & rigidity of all muscles (HALLMARK): Minimal stimuli may lead to generalized spasms
• Hyperreflexia
• Anxiousness, sweating
• Headache, delirium, sleeplessness
• Retention of urine: Spasm of urinary sphincter
• Constipation: Rectal spasm
• Dysphagia
• Dyspnoea

Autonomic instability:

Blood pressure fluctuations

• Hypertension or hypotension
• Diaphoresis
• Arrhythmias

Characteristic postures:

• Opisthotonus (backward bending)
• Orthotonus (straight posture)
• Emprosthotonus (forward bending)
• Pleurosthotonus (lateral bending)

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Complications

• Fractures, joint dislocations & tendon ruptures
  • Severe Tonic-clonic convulsions
• Haematoma
• Respiratory system:
  • Tachypnoea, respiratory distress, respiratory infections, aspiration, cyanosis, respiratory failure
• Carditis, arrhythmias
• CVT, pulmonary embolism
• Toxaemia
• Secondary infections:
  • Septicaemia
• Bedsores, malnutrition, stress gastric ulcers
• Coma & death

Cause of death (45-50% mortality):

• Respiratory failure with aspiration pneumonia & ARDS
• Severe carditis

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Diagnosis

• Microscopy: Drumstick bacilli in wound
• Culture: Swarming growth
• Toxigenicity testing:
  • in vitro: Nagler reaction
  • in vivo

Ablett classification:

Differential diagnosis:

• Strychnine poisoning
• Trismus
• Meningitis
• Hydrophobia
• Convulsive disorders

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Management

Immunization:

• Passive immunisation
  • Emergency procedure, to be used only once
  • Types:
    1. Antitetanus serum (ATS)
       • Disadvantages:
         • Immune elimination
         • Hypersensitivity
    2. Human antitetanus immunoglobulin (TIG)
       • No risk of hypersensitivity
• Active immunisation
  • M/effective method (spaced injections)
  • Available forms:
    • Plain toxoid
    • Adsorbed toxoid
  • Given as Triple vaccine or Pentavalent vaccine

Treatment:

ICU management: Isolation in dark & quiet room

• Antitetanus globulin (ATG)
  • 3000 units IM single dose
    • If not available,
      • Antitetanus serum (ATS)
        • 1000 units IV
• Antibiotic (benzylpenicillin)
• Tetanus toxoid (TT)
• Wound care: Debridement, drainage, local ATG injection

Specific measures:

• Antiepileptics:
  • IV Diazepam (4 or 6 hourly)
  • IV Phenobarbitone (4 or 6 hourly)
  • IV Chlorpromazine (4 or 6 hourly)