Case Presentation: A previously healthy 8 month old unvaccinated and exclusively breastfed female presented with 24 hours of poor feeding, irritability and decreased urine output. Initial workup revealed mild leukocytosis, anion-gap metabolic acidosis, pyuria and ketonuria raising concern for dehydration and a possible urinary tract infection. Patient was admitted for intravenous hydration and empiric antibiotics. Over the course of a few hours she developed a weak cry, progressive lethargy, difficulty managing secretions and worsening hypotonia. Overnight, she quickly became somnolent, hypothermic and developed bulbar weakness prompting a transfer to the Pediatric Intensive Care Unit. Repeat neurologic examination revealed profound axial hypotonia, flaccid paralysis, head lag, diminished gag reflex and poor respiratory effort with preserved pupillary responses. MRI brain and spine was normal. Lumbar puncture with meningitis panel was unremarkable. Due to worsening respiratory status, patient was intubated with concern for airway compromise. With progressively worsening neurological status, infantile botulism became the leading diagnosis and she received intravenous Botulism Immune Globulin after which she improved gradually. Stool was positive with Botulinum Toxin A and patient was transferred to inpatient rehabilitation for ongoing recovery.
Discussion: The differential for acute progressive hypotonia in an infant includes predominantly Guillain Barré syndrome, transverse myelitis, myopathy, neurometabolic disease and various types of encephalitis [1, 2]. Given unremarkable MRI and CSF studies, infantile botulism was considered most likely based on examination and rapid progression. Infantile botulism typically presents between 2–6 months when the gastrointestinal tract is still immature with lower gastric acidity and an underdeveloped mucosal barrier leading to the intestinal microbiome offering limited colonization resistance [3]. By 8 months, a more established gut flora usually prevents Clostridium botulinum spore germination making this case less common. This patient’s older age, history of exclusive breastfeeding and lack of environmental exposure contributed to botulism being lower on the initial differential. Her early clinical findings including poor feeding, dehydration, pyuria and constipation aligned more closely with common pediatric diagnoses such as urinary tract infection and gastrointestinal dysfunction. As her neurologic deficits progressed, Guillain Barré syndrome became a leading consideration despite a normal CSF study since early presentation within 3-5 days of onset can be accompanied with a lack of albuminocytologic dissociation [4]. Her rapid deterioration with descending paralysis, bulbar weakness and afebrile course highlighted the urgency of establishing a unifying diagnosis and ultimately pointed towards infantile botulism despite her age and lack of classic risk factors. Timely recognition of infantile botulism remains critical as early administration of Botulism Immune Globulin shortens duration and mitigates respiratory compromise [5].
Conclusions: This case underscores how atypical age, absent exposures, normal imaging and overlap with Guillain Barré syndrome can delay recognition of infantile botulism. Clinicians should maintain a high index of suspicion in infants with acute progressive hypotonia and bulbar weakness as early diagnosis and intervention are critical to improving outcomes.