(Kiosk 6) Electrophysiological Patterns in Two Cases of Infant Botulism

Case Diagnosis: Two cases of infant botulism

Case Description or Program Description: Two 3-month-old unrelated infants presented to the ED a week apart with generalized weakness, poor suck, constipation, and hypophonia. On review, one infant was taken to a pumpkin patch and the other lived in a dusty basement near a construction site.

Setting: Acute Inpatient Hospital

Assessment/Results: On electrodiagnostic evaluation of the first infant, there was a decremental CMAP response on slow (3-Hz) repetitive nerve stimulation (RNS) of the right tibial nerve with pickup over the abductor hallucis muscle. On high-frequency RNS (20-Hz), there were incremental responses. EMG revealed fibrillations of the left gastrocnemius. Similarly, electrodiagnostic evaluation of the second infant revealed decremental response with slow RNS of the left tibial nerve, incremental response with high-frequency RNS, and fibrillations in the right rectus femoris. Both infants received botulism antitoxin with resolution of symptoms.

Discussion (relevance): Botulism is a rare, potentially life-threatening syndrome of diffuse, flaccid paralysis due to botulinum neurotoxin produced by Clostridium botulinum. Approximately 110 cases of botulism are reported annually in the US. Paralysis results from irreversible inhibition of acetylcholine release into the neuromuscular junction. Entry of C. botulinum spores are often from inhalation, ingestion, or through wounds. In infants, a weak immune system allows proliferation of toxin-producing C. botulinum colonies in the digestive tract or bronchioles. The classic electrodiagnostic findings that support botulism diagnosis include decremented response with slow RNS, incremented response with high-frequency RNS, and diffuse abnormal spontaneous activities (fibrillation, positive waves). Treatment with immediate antitoxin acquisition and administration along with close monitoring and supportive care is critical. Mortality from infant botulism has significantly declined overtime with risk of death less than 1%. Recovery however can be prolonged and patients may take years to regain full functionality.

Conclusions: Infant botulism is a rare, potentially fatal condition that necessitates prompt diagnosis and antitoxin administration. These cases review the pathophysiology and classic electrodiagnostic findings of botulism.