Infant apnea syndrome. A prospective evaluation of etiologies.

The frequency of proposed causes for the infant apnea syndrome (IAS) or "near miss" sudden infant death is unknown. Using a protocol, we investigated a small series of 28 consecutive infants with IAS. This in-hospital evaluation included, for all patients, blood chemistries; x-rays of skull, lumbar puncture, chest, and barium swallow; electrocardiogram, echocardiogram, 24-hour Holter cardiac monitor; viral and bacterial cultures of blood, urine, stool, and CSF; EEG; and esophageal pH study for gastroesophageal reflux (GER). A probable cause was found in 17 of the 28 infants including GER 6, encephalitis 4, convulsive disorder 3, periventricular edema 1, Arnold-Chiari malformation 1, milk allergy 1, periodic breathing 1. Home apnea monitors were used only by three, all of whom had no diagnosis and only these three had repeat apneic episodes. There have been no deaths during follow-up of 12 to 24 months. It is our conclusion that detailed evaluation of IAS often yields a specific diagnosis. The most valuable investigations were lumbar puncture, EEG, and esophageal pH studies.