Anatomical study of preganglionic spinal nerve and disc relation at different lumbar levels: Special aspect for...

Lumbar microdiscectomy is a widespread popular method of treatment. One major challenge is the spine level dependent different anatomy and the limited sight on the nerve root during the surgical procedure.

The aim was to analyze the specific anatomic relation of nerve root, intervertebral disc and intervertebral ganglion under determination of the specific nerve distances. Furthermore the relation between the disc and the corresponding nerve root was evaluated.

Regular human lumbar spine specimens of body donors were included in the study. Microscopic assisted dissection was performed. The topographical distances between a defined disc measurement point (DP) and the corresponding nerve root shoulder (NS) were measured. The preganglionic distance from the caudal axilla point (AP) of the spinal nerve root and the center point (CG) of the spinal ganglion in the intervertebral foramen were determined.

The AP-CG distance increased gradually in the caudal direction from L1 (7.25 ± 2.72 mm right side, 7.30 ± 2.85 mm left side) to a maximum for L5 (16.00 ± 3.39 mm right side, 16.50 ± 3.58 mm left side, p< 0.05). We found a significant reduction for S1 (14.88 ± 3.42 mm right side, 13.83 ± 2.47 mm, p< 0.05). In contrast the DP-AP distances showed a maximum for L1 (12.75 ± 2.78 mm right side, 13.70 ± 3.87 mm left side) with an increasing shortening in the caudal direction and even negative values for S1 (-2.63 ± 3.31 mm right side, -0.83 ± 2.84 mm left side, p< 0.01).

The topographical anatomy changes each lumbar segment and demands therefore an exact preoperative planning using this specific knowledge to perform a successful microscopic spine surgery. The results of the study support a better understanding of the relevant anatomy and help to reduce incomplete herniated disc removal and to avoid surgical complications.