MR Imaging of the Variation in Position of the Tip of the Conus Medullaris in the Chinese Population

Objective To determine the variation in position of the conus medullaris in the Chinese population without spinal deformity through MR imaging. Methods The T1 weighted, midline, sagittal, spin echo magnetic resonance imaging studies of 1199 patients were assessed to identify the tip of the conus medullaris by using a 1.5T MRI machine. The location was recorded in relation to the upper, middle, or lower third of the adjacent vertebral body or the adjacent intervertebral disc. Results The mean conus position was at the lower third of L1 (range: middle third of T12 to upper third of L3). The variation in conus positions followed a normal distribution. The conus position in female patients was significantly lower than that in male counterparts ( P 0.001). No significant difference in conus position was seen with increasing age ( P 0.05). Conclusion MRI can show the distribution of conus location ranged from the middle one third of T12 to the upper one third of L3, and it is of significant importance to clinical anesthesia and operation. [