Morphometric evaluation of neonatal brainstem development by means of the ultrasonographic method

Development of the midbrain in 260 newborn infants was studied by means of the ultrasonographic method. The 260 infants were divided into four groups; 211 appropriate-for-date (AFD) infants without intracranial abnormalities or chromosomal disorders, 41 light-for-date (LFD) infants without intracranial abnormalities or chromosomal disorders, 5 cases of Down syndrome and 3 cases of trisomy 18. The midbrain area (MBA) was measured in transverse sections using a Sonos 1000 (YHP) within 24 h of birth. MBA of the 211 AFD infants was correlated with gestational age (GA), the standard curve being -0.0029(GA)2 + 0.2611(GA) -3.335 (r = 0.87, P < 0.0001). MBA of the other three groups were compared with this standard curve. Thirty-seven of the 41 LFD cases and all the Down syndrome infants showed MBA within 1.5 S.D. of the standard curve. However, all the infants with trisomy 18 had smaller MBA than -1.5 S.D. of the standard curve. The standard curve should be useful for assessing the gestational age of newborn infants and for detecting abnormal development of the brainstem in developmental disorders.