A case of asymmetric cranial nerve palsy due to iatrogenic botulism

Introduction: Botulism is a rare but lethal disease and atypical clinical presentations of this disease are difficult to diagnose. We report a case of iatrogenic botulism who presented withasymmetric cranial nerve involvement. Case report: An eighteen year old female with cerebral palsy, congenital hydrocephalus and left upper/lower limb spasticity accidentally received double the normal dose of Botulinum neurotoxin A (BoNTA) which was equal to 800 Units, administered intramuscularly in the aforementioned muscle groups, leading to left eyelid drooping without no additional cranial nerve palsy or sensory/motor limb deficit. Patient was hospitalized for 3 days of clinical observation during which there was no progression of symptoms to the contralateral side, and the patient was uneventfully discharged. On follow up, the patient continued to make a steady recovery. Discussion: Asymmetric muscle weakness is unusual for botulism confounded further in a patient with underlying spastic disorder. In our case, BoNTA was administered unilaterally in muscle groups, yet symptoms developed remotely from the injection site. Factors causing this could be large antero and retrograde axonal transport or from systemic uptake from nearby capillary beds. There is no current consensus on an optimal therapeutic injection dose for BoNTA in children or adults. Conclusion: Physicians should be aware that asymmetric iatrogenic botulism of the cranial nerves may occur from a botulinum toxin injection into a site that is anatomically remote from the face.