Discussion
Low-dose botulinum toxin is widely used as a cosmetic treatment and for various medical conditions, such as muscle spasticity, cervical dystonia and chronic migraines. The toxin is produced by the Gram-positive, anaerobic, rod-shaped bacterium Clostridium botulinum and ranks among the most potent natural toxins. Paralysis occurs in high doses, which can lead to respiratory failure and death. Seven serotypes (types A–G) have been identified, with A, B, E and F capable of causing botulism in humans (1).
From 1977 to 2022, 81 cases of botulism were reported in the Norwegian Surveillance System for Communicable Diseases. Of these, 37 were foodborne, 26 were wound botulism associated with subcutaneous drug use, and 8 were cases of infant botulism. The mode of transmission was not recorded for the remaining cases (2). A common cause of botulism in Norway is the consumption of contaminated rakfisk (a salted and fermented fish dish) or cured meat, where patients typically develop abdominal pain, vomiting and diarrhoea within 12–36 hours, accompanied by dry mouth, ptosis, diplopia, speech problems, paresis and constipation (2).
Botulism as a complication of medical and cosmetic injections is less known and often associated with incorrect administration or overdosing (3). In February and March 2023, 87 cases of botulism were reported following intragastric injections for weight management treatment in Turkey (4). Some patients exhibited severe symptoms, and several required intensive care and antitoxin treatment (4). In a European prospective study, preliminary data were recorded on 22 German patients who developed botulism after such treatment in Turkey. This included injections with 1000–2500 units of botulinum toxin A, which is much higher than the maximum dosage of 500 units per treatment recommended for the most widely sold botulinum toxin A preparations in Norway (5, 6). It is uncertain what dose our patient received, as no information on dosage was available.
Botulinum toxin can be indirectly detected by inoculating mice (mouse test) with the patient's serum. New promising tests that are more sensitive and do not involve animals are not available in Norway (7). Among the first 12 German patients, all with a negative mouse test, toxin was detected in nine using an Endopep-MS assay. The available test methods are thus not sensitive enough, and a negative mouse test does not rule out botulism if clinical findings are consistent (5).
In cases of suspected wound or foodborne botulism, the recommended treatment is rapid (within 48 hours) infusion of heptavalent antitoxin produced in an immunised horse and supplied by the Norwegian Institute of Public Health. Antitoxin treatment has shown better survival rates in animal experiments, while data and clinical experience with iatrogenic botulism are limited (5, 8). In a Chinese observational study of 86 patients with iatrogenic botulism after receiving cosmetic botulinum toxin A injections, dosages ranged from 6 to 1000 units. Symptoms developed within 0 to 36 days, with the most common being headache, dizziness, fatigue, blurred vision, ptosis and dysphagia. All received antitoxin treatment, which was reported to be effective and without serious adverse effects (9).
The mouse test indicated that free toxin might be present in our patient. It is unclear whether the clinical deterioration beyond one week after injection was due to effects in neurons from initial toxin binding, or if free toxin was still present (3). In a more recent case study, a patient with progressing paralysis was treated 15 days after receiving a botulinum toxin A injection, with observed improvement (10).
Systemic distribution and the efficacy of antitoxin treatment are under-researched, but due to the increasing trend of 'beauty and health tourism' abroad, we are likely to see more cases of iatrogenic botulism where antitoxin treatment needs to be considered.