Tetanus

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Introduction

  • A neurologic disorder characterized by increased muscle tone and spasm that is caused by tetanospasmin, a powerful protein toxin elaborated by Clostridium tetani. 
  • C. tetani is ubiquitous, and therefore affects all ages and sexes, especially in low socioeconomic settings.

  • The bacteria are found in the soil, inanimate environment, animal faeces and occasionally in human faeces.

  • Portals of entry:

    • Umbilical stump
    • Female genital mutilation (FGM)
    • Male circumcision
    • Abortion sites
    • Penetrative wounds (e.g. nail puncture or intramuscular injection)
    • Head injury; scalp wounds
    • Traditional scarification (e.g. for tribal identity)
    • Trado-medical incisions
    • Post-operative surgical sites
    • Chronic otitis media

Clinical features

Generalized tetanus

  • Lock jaw
  • Dysphagia
  • Stiffness or pain in the neck, shoulder and back muscles
  • Rigid abdomen and stiff proximal limb muscles
  • Intermittent reflex spasms in response to stimuli (eg, noise, touch)
  • Opisthotonos (ie, flexion and adduction of the arms, clenching of the fists, and extension of the lower extremities).
  • Consciousness and sensorium are intact

Neonatal tetanus

  • Poor feeding
  • Irritability
  • Rigidity
  • Spasms
  • Poor prognosis

Localized tetanus

  • Increased tone; spasms are restricted to the muscles near the wound
  • Prognosis is good

Cephalic tetanus

  • Follows head injury or ear infection
  • Trismus
  • Dysfunction of one or more cranial nerves, often the 7th nerve
  • Mortality is high

Diagnosis

  • Entirely clinical

Differential diagnoses

  • Alveolar abscess
  • Strychnine poisoning
  • Dystonic drug reactions
  • Hypocalcaemic tetani
  • Meningitis/encephalitis
  • Acute abdomen

Complications

  • Autonomic dysfunction
    • Labile or sustained hypertension
    • Tachycardia
    • Dysarrhythmias
    • Hyperpyrexia
    • Profuse sweating
    • Peripheral vasoconstriction
    • Cardiac arrest
    • Aspiration pneumonia
    • Fractures
  • Muscle rupture
  • Deep vein thrombophlebitis
  • Pulmonary emboli
  • Decubitus ulcers
  • Rhabdomyolysis

Investigations

  • Wound swab for microscopy, culture and sensitivity
  • Cerebrospinal fluid for biochemistry; microscopy, culture and sensitivity most
  • Full Blood Count; ESR
  • Urinalysis; urine microscopy, culture and sensitivity
  • Blood glucose
  • Electrocardiography
  • Serum Electrolytes, Urea and Creatinine
  • Electromyography

Treatment goals

  • Eliminate the source of toxin
  • Neutralize unbound toxin
  • Prevent muscle spasms
  • Monitor the patient's condition and provide support (especially respiratory support) until recovery

Non-drug treatment

  • Admit patient to a dark and quiet room or intensive care unit where available
  • Protect airway
  • Explore wounds
    • Cleanse and thoroughly debride the wound
  • Provide intubation or tracheostomy for hypoventilation
  • Physiotherapy
  • Monitor bowel, bladder and renal function
  • Prevent decubitus ulcers

Drug treatment

Antibiotics

  • Metronidazole
  • Adult: 500 mg intravenously, every 6 hours for 10 days
  • Child
    • neonate, initially 15 mg/kg by intravenous infusion then 5 mg/kg twice daily
    • 1 month - 12 years: 5 mg/kg (maximum 400 mg) every 8 hours
    • 12 - 18 years: 400 mg every 8 hours

Or:

  • Benzylpenicillin (Penicillin G)
  • Adult: 6 - 2.4 g daily by slow intravenous injection or infusion in 2 - 4 divided doses; higher doses in severe infections
  • Child:
    • 1 month - 18 years, 100 mg/kg in 4 divided doses, every 6 hours; dose doubled in severe infections (maximum 4 g, every 4 hours)
    • 1 - 4 weeks: 75 mg/kg daily in 3 divided doses, every 86 hours; dose doubled in severe
    • Preterm neonate and neonate under 7 days: 25 mg/kg, every 12 hours; dose doubled in severe infection.
    • NB: Metronidazole is preferable as penicillin is a known antagonist of gamma-aminobutyric acid (GABA), as is tetanus

Antitoxin

  • Human tetanus immune globulin (TIG)
  • Adult: TIG 500 units by IM injection or intravenously (IV)—depending on the available preparation
  • Administer antitoxin before manipulating the wound
  • In addition, give 5 mL of tetanus toxoid by IM injection at a separate site.
  • Tetanus disease does not induce immunity; patients without a history of primary TT vaccination should receive a second dose 1–2 months after the first dose and a third dose 6–12 months

Control of muscle spasm

  • Diazepam
  • Adult: 20 mg intravenously slowly stat and titrate up to 250 mg/day in infusion
  • Child: 1 month - 18 years: 100 - 300 μg/kg repeated every 1 - 4 hours by slow intravenous injection; could also be administered by intravenous infusion or by nasoduodenal tube as follows: 3 - 10 mg/kg over 24 hours, adjusted according to response.

Or:

  • Phenobarbital (dilute injection, 1 in 10 with water for injection)
  • Adult: 10 mg/kg intravenously at a rate of not more than 100 mg/minute, up to maximum total dose of 1 g
  • Child: 5 - 10 mg/kg at a rate not more than 30 mg/minute
  • Treat autonomic dysfunction with vasopressors, chronotropic agents if necessary
  • Hydration: To control insensitive and other fluid losses
  • Enteral or parenteral nutrition as determined by clinical situation
  • Treat intercurrent infections.

Treatment of tetanus-prone wounds

  • TIG by intramuscular injection, Adult and Child: 250 units,
  • Increased to 500 units if wound older than 12 hours or there is risk of heavy contamination or if patient weighs more than 90 kg
  • Second dose of 250 units given after 3–4 weeks if patient is immunosuppressed or if active immunization with tetanus vaccine contraindicated.

Notable adverse drug reactions, contraindications and caution

  • Diazepam is adsorbed from plastics of infusion bags and giving sets; causes drowsiness and light headedness; hypotension
  • Benzyl penicillin: hypersensitivity reactions
  • Metronidazole: taste disturbances
  • Phenobarbital: caution in renal and hepatic impairment 
  • May cause paradoxical excitement, restlessness and confusion in the elderly; hyperkinesia in children

Prevention

  • Active immunization of all partially or un-immunized adults, those recovering from tetanus, all pregnant women, infants and un-immunized (missed) children
  • Health education
  • Improvement in socio-economic status