Overview
Tetanus is caused by tetanospasmin, a toxin produced by Clostridium tetani, resulting in spasms, rigidity, and trismus. It can be described as:
- Generalised tetanus – more common, tetanus in all/most parts of the body
- Localised tetanus – less common, tetanus at the site of injury, may progress to generalised tetanus
Pathophysiology
Clostridium tetani spores can be found in soil and in the gastrointestinal tracts of animals. Transmission is usually by introducing spores into open wounds (e.g. injuries or intravenous drug use). Clostridium tetani produces tetanospasmin, a neurotoxin which blocks the release of inhibitory neurotransmitters (e.g. GABA), resulting in excess muscle contraction and impaired relaxation.
Epidemiology
- Tetanus is rare in the UK, with around 10 cases/year due to immunisation
- It is more common in poorer countries
Risk Factors
- Lack of immunisation
- Wounds contaminated with soil (e.g. rusty metal garden tools)
- Intravenous drug use
- Poverty
- Older age (>60 years old)
- Neonatal tetanus: bacteria can enter the umbilical stump – more common in rural areas and deliveries at home
Presentation
Generalised tetanus is more common than localised tetanus. Its features include a prodrome (fever, headaches, malaise) followed by a descending pattern of :
- Trismus (lockjaw) – an inability to move the mouth due to spasm
- Risus sardonicus describes a grin-like expression due to spasms and is a late feature
- Neck and back stiffness:
- This can progress to opisthotonus, which describes an arched body and hyperextended neck
- Dysphagia
- Increased tone and hyperreflexia
- Autonomic dysfunction – tachycardia, arrhythmia, hyper-/hypotension, fever
Localised tetanus tends to be milder, with features restricted to muscles near the wound, however, it can progress to the generalised form.
Diagnosis
Overview
The diagnosis of tetanus is clinical and testing is not usually necessary.
Management
Acute tetanus
Treatment is supportive (such as intensive care and artificial ventilation) and includes metronidazole. Tetanus immunoglobulin and vaccination may be given in specific circumstances (listed below).
Immunisation
The tetanus vaccine contains a purified toxin that is given routinely as part of a combined vaccine in 5 doses:
- 2 months
- 3 months
- 4 months
- 3-5 years
- 13-18 years
Tetanus and wound management
Decisions regarding tetanus and wound management first depend on the classification of the wound (the Green Book has further details):
- Clean wounds:
- <6 hours old
- Non-penetrating injury
- Negligible tissue damage
- Tetanus-prone wounds:
- Puncture/penetrating injury in a contaminated environment (e.g. gardening)
- Wounds containing foreign bodies
- Compound fractures
- Wounds/burns with sepsis
- Some animal bites and scratches
- High-risk tetanus prone wounds:
- Heavy contamination with a material that is likely to contain tetanus spores (e.g. soil, animal faeces)
- Wounds/burns that require surgery
- Wounds/burns with extensive devitalised tissues
They also depend on if the patient has had a full course of tetanus vaccines:
- Full course + last dose <10 years ago:
- No vaccine or immunoglobulin is needed, regardless of severity
- Full course + last dose >10 years ago:
- If tetanus prone: give a reinforcing vaccine dose
- If high-risk: give reinforcing vaccine dose + tetanus immunoglobulin
- Vaccination history incomplete/unknown:
- Give reinforcing vaccine dose, regardless of severity
- If tetanus prone/high-risk: give reinforcing vaccine dose + tetanus immunoglobulin
Complications
- Fractures – due to sustained muscle spasms being severe enough to fracture bones
- Rhabdomyolysis – due to sustained muscle contraction, leading to muscle breakdown and acute kidney injury
- Aspiration – due to impaired gastrointestinal motility
- Autonomic dysfunction – including labile blood pressure, arrhythmia, and cardiac arrest
- Deep vein thrombosis/pulmonary embolism – due to prolonged immobilisation
