Overview
Botulism is caused by the botulinum toxin produced by Clostridium botulinum. This is a neurotoxin that interferes with the release of acetylcholine at the presynaptic end of a neuromuscular junction, causing acute paralysis.
Risk Factors
- Ingesting contaminated food – such as tinned foods
- Intravenous drug use
- Infant botulism – due to an immature gut, caused by exposure to contaminated soil, eating honey
- Wound contamination
- Iatrogenic – as botulinum toxin is ‘Botox’
Presentation
The key feature is flaccid paralysis with no sensory disturbance, however, the presentation can vary depending on the cause:
- Foodbornebotulism:
- Bilateral cranial nerve palsies – blurred vision, diplopia, dysphagia, and slurred speech
- Followed by descending, symmetrical paralysis after eating contaminated food
- There may be abdominal pain
- Infant botulism:
- Constipation is the most common
- Other features include dysphagia, a weak cry, hypotonia, and ptosis
- Other types (e.g. wound botulism) present similarly without gastrointestinal symptoms
Investigations
Overview
Botulism is diagnosed clinically, with tests to confirm its presence:
- Botulinum toxin assay:
- Identifies toxins and may be done using serum, food samples, or stool
Management
Overview
Management involves the use of botulinum antitoxin and supportive care including artificial ventilation. The antitoxin is only useful if given early, as once the toxin has bound to a neuromuscular junction, it cannot be reversed.
Prognosis
- Mortality rates are low at around 5%, however, recovery can take months to years
