RESUMEN
BACKGROUND: Intussusception encephalopathy, a misleading form in which neurological symptoms are obvious, is classic but rarely described. CASE REPORT: A 21 month-old infant was admitted because he had suffered from fluctuating consciousness and apathy for a few hours. Vomiting occurred soon afterwards. Search for dehydration, meningitis, encephalitis, poisoning... was negative; the abdomen was tender leading to ultrasonography that showed a sausage-shaped tumor. The ileocolic intussusception was successfully reduced with a gas enema. CONCLUSION: A striking degree of lethargy associated with vomiting may overshadow to a considerable extent the classical intestinal manifestations. A possible endogenous opioid poisoning by massive secretion of endorphins during pain's paroxysm is one of the hypotheses explaining this type of presentation.