LONGITUDINAL DEVELOPMENT OF THE SPINE AND SPINAL CORD IN HUMAN FETUSES

ABSTRACT Objective The spinal cord extends from the foramen magnum to the sacrum in the human fetus at the beginning of the 2nd quarter. However, the medullary cone is located at or above the level of the second lumbar vertebra at birth. The objective is to determine the difference between the rates of longitudinal growth of the spinal cord and the spine in human fetuses from the 13th to the 22nd week of gestation (WoG) using magnetic resonance imaging (MRI). Methods Descriptive observational cross-sectional study of 24 stillbirths (13 ♂, 11 ♀), between the 13th and 22nd WoG, using spinal MRI. We recorded spine and spinal cord lengths in millimeters from the foramen magnum to the coccyx for the former and to the medullary cone for the latter. We identified the position of the medullary cone according to vertebral level and its correlation with the gestational age and the literature. Results The spinal cord increased in length from 50 to 93 mm, the spine from 57 to 137 mm, and the medullary cone rose from S1 to L2. The rate of growth was 1.2 mm/day for the spine and 0.6 mm/day for the spinal cord. Conclusions Discordance in the rate of normal longitudinal growth of the spine and spinal cord caused the medullary cone to rise from S1 level to L2 in the second trimester of pregnancy. These results allow an understanding of normal development and certain congenital malformations. Level of evidence IV; Case series