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Internal Medicine

Tetanus

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

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

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
Tetanus
The Calgary Guide | http://calgaryguide.ucalgary.ca/

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)

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

Diagnosis

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

Ablett classification:

Ablett classification of severity of tetanus
Ablett classification of severity of tetanus | A lethal case of generalized tetanus – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Ablett-classification-of-severity-of-tetanus_tbl2_49856865 [accessed 25 Jul, 2022]

Differential diagnosis:

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

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)

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