Morphometric Analysis of Neurocentral Synchondrosis Using Magnetic Resonance Imaging in the Normal Skeletally Immature Spine

STUDY DESIGN: Morphometric analysis of the neurocentral synchondrosis (NCS) using magnetic resonance imaging in the normal infantile and juvenile patients. OBJECTIVES: To assess the developmental stages of the neurocentral synchondrosis (NCS) by determining the age at which closure of the NCS occurs at specific levels of the spine and to evaluate whether symmetric growth of the NCS occurs during the different developmental stages in normal immature spine. SUMMARY OF BACKGROUND DATA: The function and developmental stage of the NCS are controversial because of a lack of agreement on the exact age of closure. To date, most authors believe that the NCS is actively open at a very early age, but the reported age of closure of the NCS varies from age 3 to 16 years. This various closure age of the NCS has resulted in some confusion about the role of the NCS in the normal spinal growth or the development of spinal deformity. METHODS: A total of 34 normal pediatric patients who had axial magnetic resonance images from first thoracic vertebra to fifth lumbar vertebra were assigned into following 3 groups: infantile group (n = 11), 0 to 3 years of age; juvenile-young group (n = 16), 4 to 7 years of age; and juvenile-old group (n = 7), 8 to 10 years of age. T2-weighted axial magnetic resonance images were used to analyze the NCS developmental stages using a custom 6-point scale (0: actively open with 0% closure; 5: 100% NCS closure). For the stage 0 closure NCS, the width and thickness of the NCS were measured. RESULTS: The NCS was actively open without closure for all less than 4-year-old patients at all levels. The NCS had approximate 75% closure in the lumbar region at 4 years of age while the thoracic NCS remained nearly open. After 5 years of age, the middle-lower thoracic NCS began to close with closure rate less than 25%. At the 10 years of age, the NCS in the lumbar region had near 100% closure, whereas the thoracic NCS demonstrated approximate 50% closure. For the NCS without closure, the average width and thickness were 7.6 x 1.3 mm on the left and 7.9 x 1.3 mm on the right, which was not significantly different. For the NCS with closure, the left and right NCS closure rates were not significantly different. CONCLUSION: The NCS developmental stage is age- and vertebral level-dependent. The NCS closes from the lumbar and proximal thoracic spine to the middle-distal thoracic spine and times from very early juvenile to the adolescent. The NCS symmetry bilaterally occurred not only during the active open, but also the long closure period. The NCS symmetric open and/or closure may be important to maintain the normal spine alignment.