A 3-month-old full-term boy is brought to the emergency department for refusal to feed. The infant has been exclusively breastfed since birth but has not been latching onto the nipple. He has been urinating normally and usually stools 3 or 4 times a day, but his last bowel movement was several days ago. He was previously able to hold his head up on his own but his head now seems floppy. The patient's family recently moved to California and has been enjoying stroller walks in their newly built neighborhood. Other than daily vitamin D supplementation, the infant has never ingested food, even honey. Vital signs are normal. Examination shows bilateral ptosis, sluggish pupillary reaction to light, copious drool, weak suck and gag reflexes, and head lag. The extremities are flaccid and in extension. What is the most likely mechanism of this patient's illness?

Question

A 3-month-old full-term boy is brought to the emergency department for refusal to feed.  The infant has been exclusively breastfed since birth but has not been latching onto the nipple.  He has been urinating normally and usually stools 3 or 4 times a day, but his last bowel movement was several days ago.  He was previously able to hold his head up on his own but his head now seems floppy.  The patient's family recently moved to California and has been enjoying stroller walks in their newly built neighborhood.  Other than daily vitamin D supplementation, the infant has never ingested food, even honey.  Vital signs are normal.  Examination shows bilateral ptosis, sluggish pupillary reaction to light, copious drool, weak suck and gag reflexes, and head lag.  The extremities are flaccid and in extension.  What is the most likely mechanism of this patient's illness?

Quizplus · Accepted Answer

11ec25c8_d593_c24e_bc81_7303efa6a231_MD0003_00 This is a classic case of infant botulism caused by Clostridium botulinum. The incidence is highest in California, Pennsylvania, and Utah, which have the greatest concentrations of soil botulism spores. Ingestion of inhaled botulism spores from environmental dust (eg, construction sites) leads to colonic colonization of C botulinum. This is followed by production and release of botulinum toxin, which blocks acetylcholine release at presynaptic neuromuscular junctions. Ingestion of raw honey also is a risk factor and the only preventable means of acquiring the infection. The diagnosis should be suspected in infants with bilateral bulbar palsies (eg, ptosis, sluggish pupillary response to light, poor suck and gag reflexes) followed by symmetric descending flaccid paralysis (hypotonia). Constipation and drooling due to autonomic dysfunction also occur. Treatment involves respiratory support, nasogastric tube feeding, and intravenous human-derived botulism immune globulin. Botulism immune globulin should be administered as soon as possible, even before diagnostic confirmation of stool spores or toxin. (Choice A) The demyelinating polyradiculoneuropathy in Guillain-Barré syndrome progresses from the lower extremities and upward to the rest of the body. In contrast, botulism proceeds in a cephalocaudal pattern. (Choice B) Congenital myasthenia gravis is a rare neuromuscular disorder that can be distinguished from botulism by the lack of autonomic symptoms (constipation, drooling) and fluctuating generalized hypotonia. (Choice C) Meningitis can cause generalized weakness and poor feeding. However, normal temperature, heart rate, and blood pressure distinguish botulism from meningitis. (Choice D) Spinal muscular atrophy (Werdnig-Hoffmann disease) is characterized by generalized symmetric proximal muscle weakness and hyporeflexia. In contrast to botulism, spinal muscular atrophy does not affect the pupils, and the weakness is greater in the lower than the upper extremities. (Choice E) Clostridium difficile toxin is responsible for pseudomembranous colitis and most commonly presents as diarrhea (not constipation) after antibiotic exposure. C difficile is rarely symptomatic in infants due to lack of intestinal receptors at this age. (Choice G) Foodborne botulism results from ingestion of canned food contaminated by preformed botulinum toxin. The presentation differs from infant botulism in that the descending flaccid paralysis is preceded by a prodrome of nausea, vomiting, abdominal pain, and diarrhea. Educational objective: Infant botulism is caused by the ingestion of Clostridium botulinum spores, which colonize the gut and lead to production and release of a neurotoxin responsible for life-threatening, descending flaccid paralysis. The diagnosis should be considered when a previously healthy infant presents with bulbar palsies, constipation, and hypotonia, even if the infant has not been fed honey. Human-derived botulism immune globulin is the treatment of choice. References: Clinical mimics of infant botulism. (http://www.ncbi.nlm.nih.gov/pubmed/17403857) Global occurrence of infant botulism, 1976-2006. (http://www.ncbi.nlm.nih.gov/pubmed/18595978) Infant botulism: a 30-year experience spanning the introduction of botulism immune globulin intravenous in the intensive care unit at Children's Hospital Los Angeles. (http://www.ncbi.nlm.nih.gov/pubmed/18055655)

A 3-Month-Old Full-Term Boy Is Brought to the Emergency Department