Cerebrospinal fluid endorphins and the infant apnea syndrome.

Cerebrospinal fluid (CSF) beta-endorphin levels were determined in 16 patients with infant apnea syndrome and 34 control patients. A statistically significant difference (P less than or equal to .0001) was found with the infant apnea syndrome patients having beta-endorphin levels of 14.7 +/- 1.2 pmol/L (mean +/- SE) and the controls having levels of 6.9 +/- 0.6 pmol/L (mean +/- SE). To test whether these elevated CSF beta-endorphin levels were the result or the possible cause of the apneas, three patients with infant apnea syndrome and abnormal CSF beta-endorphin levels participated in a study to determine whether a continuous low-dose infusion (10 micrograms/kg/h) of the narcotic antagonist naloxone would reduce the occurrence of apneas and respiratory pauses during all-night polysomnogram recordings. A fourth patient with documented apneas but normal CSF beta-endorphin levels was also studied while on a regimen of naloxone. In the patients with infant apnea syndrome and abnormal CSF beta-endorphin levels, a significant (P less than or equal to .05) reduction in apneas and respiratory pauses occurred during naloxone infusion. There was no change in the occurrence of apneas or respiratory pauses during naloxone infusion in the patient with normal CSF endorphin levels. Abnormal CSF levels of endorphins may play a role in apneas of infancy and may be amenable to therapy with narcotic antagonists.