Tetanus Flashcards
Define Tetanus, probable tetanus by CDC
It is an acute disease manifested by skeletal muscle spasm and autonomic nervous system disturbance.
The CDC defines probable tetanus as an acute illness with muscle spasms or hypertonia in the absence of a more likely diagnosis.
Define neonatal tetanus
Neonatal tetanus is defined by WHO as an illness occurring in a child who has the normal ability to suck and cry in the first 2 days of life but who loses this ability between 3 and 28 days of life and becomes rigid and has spasms.
Define maternal tetanus
Maternal tetanus is defined by WHO as tetanus occurring during pregnancy or within 6 weeks after conclusion of pregnancy (whether with birth, miscarriage and abortion.
What is the epidemiology of tetanus
Tetanus is a rare disease in the developed world.
In a 14 year prospective study carried out in a tertiary health facility in Northwest Nigeria, they found a prevalence of 6.5 cases per year with a complication rate of 71.4% and a mortality rate was 48.4%.
Globally, 7% of neonatal deaths was as a result of tetanus, but the incidence is up to 20% in Nigeria.
Almost always affects the non-immunized
Common in
areas where soil is cultivated
rural areas
warm climate
during summer months
among males
What is the aetiology of tetanus?
Causative agent, characteristics of organism, sources and sources of neonatal
- Causative organism is Clostridium tetani.
*Poorly motile, spore-forming, anaerobic obligate, non encapsulated gram-positive bacillus
- Sources: soil, human and animal feces, house dust, clothing, air, slums, marine and freshwater sediments.
- Neonatal tetanus, source of infection is following infection of umbilical stump,
- open dirty wound, otitis media and circumcision or ear piercing
What are the Risk Factors?
- Acute injury (puncture wound, laceration, abrasion, etc, may be major or trivial
- No identifiable injury or portal in some cases (20-30%)
- Chronic conditions: skin ulcers, abscesses, and gangrene
- Burns, frostbite, middle-ear infection, surgery, abortion, childbirth, body piercing, “skin popping
Discuss clostridium, what exotoxins does it release
What is the minimal lethal dose of tetanospamin?
Clostridium produces two exotoxins: Tetanolysin and tetanospasmin.
- Tetanolysin: increases tissue necrosis and optimises condition for multiplication of bacteria.
- Tetanospasmin: implicated in tetanus.
Very low concentrations of this highly potent toxin can result in tetanus (minimal lethal human dose is 2.5ng/kg).
What is the pathogenesis of tetanus?
Spores may remain dormant for years
Spores become vegetative form in wounds under anaerobic conditions
Spores are resistant to heat, desiccation and disinfectants.
Discuss Tetanospasmin
Tetanospasmin is a 150 kDa polypeptide heteromer ;2 chains - 100kDa(heavy chain) & 50kDa (light chain) chains joined by a disulphide bond.
Tetanospasmin is intra axonally transported to the motor nuclei of cranial nerves or anterior horn of spinal cord.
What is the process?
- Heavy chain binds to the lower portion of the terminal neuron
- Leading to uncontrolled disinhibited discharge from motor neurons
- Tetanospasmin is intra axonally transported to the motor nuclei of cranial nerves or anterior horn of spinal cord.
- Once inside, the neuron toxin enters a retrograde transport pathway whereby it is carried proximally to the motor neuron body.
- In the anterior horn of the spinal cord, it is then taken by presynaptic terminals of the inhibitory spinal interneurons with the aim of inhibiting the release of inhibitory neurotransmitters (glycine and GABA).
- This results in excessive discharge from the alpha motor neurons.
- This leads to intense muscular rigidity and spasm.
- Muscles of the jaw, face, and head often involved first due to shorter axonal pathways.
- Once the toxin becomes fixed to neurons, it cannot be neutralized with antitoxin. (Neuronal binding of toxin is irreversible).
- Recovery requires the growth of new nerve terminals
What symptoms occur after infection?
- Loss of reflex inhibition of antagonist muscle groups
- Co-contraction of agonist and antagonist muscles
- intensely painful spasms, may lead to fractures & tendon rupture
What causes the autonomic tetanus symptoms?
Pre-ganglionic sympathetic neurons in the lateral horns and the parasympathetic centers are later affected
This leads to disinhibited autonomic discharge resulting in sympathetic over activity and excessive plasma catecholamine levels resulting in the autonomic symptoms.
What is the natural history of the disease?
- Incubation period( time from injury to first symptom): Averages 7–10 days, with a range of 3 days–3 weeks
- Period of onset (onset time): time interval between trismus (lockjaw) and first spasm
- 1st week - muscle rigidity and spasms, which increase in severity.
- Autonomic disturbance usually starts several days after the spasms and persists for 1–2 week
- Spasms reduce after 2–3 week
- Rigidity may persist considerably longer
What are the clinical forms of tetanus?
Generalized
Localized
Cephalic
Neonatal
What is Generalized tetanus?
Most common form
Characterized by generalized rigidity & spasms
Trismus (lockjaw); usually the 1st
Due to masseter rigidity
Risus sardonicus: a grimace or sneer
from sustained contraction of the facial muscles
What are the clinical features of tetanus?
- Stiffness and spasms of bulbar, neck, trunk and limb muscles
- Opisthotonos (arched back): Extensors are stronger than Flexors.
- Board-like abdominal rigidity
- Consciousness is preserved
- Spasms of laryngeal muscles may cause fatal asphyxia
What are local and cephalic tetanus?
LOCAL TETANUS
Uncommon form and rigidity & spasms restricted to muscles around the wound.
The prognosis is excellent
CEPHALIC TETANUS
Follows wounds of the face and head and incubation period is usually short
Affected muscles are weak or paralysed
What is Neonatal tetanus?
How is it preventable and what is the most common cause?
Causes > 50% of deaths from tetanus worldwide
Presentation: within a week of birth
A short history of failure to feed, vomiting, and ‘convulsions’.
Spasms are generalized
Mortality is high
Poor umbilical hygiene is the cause
Entirely preventable by maternal vaccination.
What are the Autonomic Features of tetanus?
- Peripheral vasoconstriction
- Bradycardia
- Hypotension
- Sudden cardiac arrest
- Urinary retention
- Labile or sustained hypertension
- Tachycardia
- Dysarhythmia
- Hyperpyrexia
- Profuse sweating
What is the management of tetanus?
What is the NECS principle?
- Diagnosis is majorly clinical i.e the history and clinical examination
- This is a medical emergency and requiring multidisciplinary approach best managed in a high dependency unit using the following principles(NECS):
- Resuscitation
- Neutralize the unbound toxin
- Eliminate the organism
- Control Spasms
- Supportive Therapy
Discuss resuscitation as a management strategy for tetanus
RESUSCITATION: ABC, Brief history, examination
NEUTRALIZE UNBOUND TOXINS: Ideally, Tetanus immunoglobulin(Recombinant) 3 000-6000 units i.v. and IM. Antiserum(equine origin-horses), 10 000 units i.v. and 10,000 IM after a negative SC test dose.
ELIMINATE ORGANISM: IV METRONIDAZOLE 500mg 6hrly, Erythromycin, vancomycin, and clindamycin are alternative AVOID PENICILLINS
wound debridement, open wound dressing.
Discuss control spasms as a management strategy for tetanus
CONTROL SPASMS
High dose Diazepam, up to 240 mg/day i.v. in divided doses. That is given as infusion. 40mg of diazepam into 1 pint of Normal saline run for 4hours and do it 6 times in a day.
Other alternatives: IM Chlorpromazine(25mg 12hrly stat and titrate as required), Phenobarbitone
When severe e.g with laryngospasm: Pancuronium with Artificial ventilation(ICU) or even tracheostomy(for endotracheal intubation of up to 2 weeks)
Discuss supportive therapy as a management strategy for tetanus
SUPPORTIVE THERAPY :Nurse in a dark, quiet environment, NG Tube,
Adequate fluid and caloric intake : N/S alternate with 5%D/S ensure at least 4L of fluid (remove myoglobin), glucose monitoring, BP and SPO2 monitoring.
Bowel and bladder care
Regular turning in bed
Supportive Treatment in cases of autonomic dysfunction:
Inotropic support with dobutamine or dopamine
Atropine for bradycardia
Intravenous beta blockers: Esmolol, or labetalol
Verapamil : sinus tachycardia
What are the complications associated with tetanus?
Respiratory: Laryngeal spasm, sedative associated obstruction, aspiration pneumonitis, pulmonary emboli ,apnoea hypoxia.
Musculoskeletal Fractures, tendon tear, muscle rupture, rhabdomyolysis, decubitus ulcer, deep-vein thrombophlebitis.
Renal: Renal failure: dehydration, sepsis, rhabdomyolosis, altered renal blood flow, urinary infection & stasis
Gastrointestinal: Ileus, weight loss, sepsis
