Unusual Presentation of Propionic Acidemia Mimicking Botulism in an Infant: A Case Report and Literature Review.

Propionic acidemia (PA) is a rare metabolic disorder stemming from genetic mutations, often causing hyperammonemia, acidosis, and basal ganglia issues. Its symptoms range from vomiting to neurological abnormalities, with severe cases presenting in neonates. Neurological complications including stroke-like episodes are common, requiring immediate attention. An eight-month-old boy with PA presented to the emergency department with respiratory distress, cough, and lethargy. Initial evaluation showed acidemia and elevated ammonia levels. He tested positive for rhinovirus and was diagnosed with acute viral bronchiolitis. While his respiratory symptoms improved, he developed neurological deficits, including hypotonia and weakness. Neurology consultations explored possible diagnoses such as botulism or acute inflammatory demyelinating polyneuropathy (AIDP). Imaging revealed basal ganglia abnormalities consistent with PA progression. Due to aspiration risk, he was transferred to the pediatric intensive care unit for supportive care. Despite unremarkable lumbar puncture and MRI results, new metabolic brain changes were noted, particularly in the basal ganglia. He was managed for weakness and feeding difficulties due to a metabolic stroke. After adjusting nutritional support and discussing long-term feeding options, he was discharged on day 29 with a nasogastric tube due to his inability to meet caloric goals orally. Neurological complications in PA, such as basal ganglia abnormalities and stroke-like episodes, are well-documented. Our case illustrates how an acute respiratory illness can obscure underlying neurological deficits, leading to delayed diagnosis. Symptoms resembling other conditions, such as descending hypotonia in our case, broaden the differential diagnosis to include botulism toxicity and AIDP. This report demonstrates the variety of clinical features patients with PA can present with and the importance of working up a metabolic crisis in addition to conditions with overlapping symptoms.