Segment-Specific Orientation of the Dorsal and Ventral Roots for Precise Therapeutic Targeting of Human Spinal Cord.

OBJECTIVE: To discuss and show the anatomical features of the spinal cord roots across spinal segments in humans.

PATIENTS AND METHODS: From October 28, 2018, to November 22, 2018, we collected and analyzed the measurements of the spines, spinal cords, and dorsal and ventral roots (C2-L5) of nine adult cadavers (five males and four females).

RESULTS: The results of this study showed less variability in rostral root angles compared with the caudal across all spinal segments. Dorsal and ventral rootlets were oriented mostly perpendicular to the spinal cord at the cervical level and had more parallel orientation to the spinal cord at the thoracic and lumbar segments. The number of rootlets per root was greatest at dorsal cervical and lumbar segments (8.41±1.91 mm and 7.91±1.94 mm, respectively; P<.001). Spinal cord transverse diameter and width of the dorsal columns were largest at cervical segments (12.86±1.13 mm and 6.84±0.93 mm, respectively; P<.001). The strongest correlation between spinal cord and vertebrae structures was found between the length of intervertebral foramen to rostral rootlet distance and vertebral bone length (R=0.82; P<.001).

CONCLUSION: These results demonstrate stable variation in spinal cord anatomical features across all tested subjects. The results of this study can be used to locate spinal roots and spinal cord landmarks based on bone marks on computed tomography or X-rays and provide background for future correlations between anatomy of the spinal cord and spinal column that could improve stereotactic surgical procedures and electrode positioning for neuromodulation procedures.