Exploring the Feasibility of Intradural and Extradural Nerve Transfers in the Management of Lumbosacral Plexus Injuries: An Anatomical Cadaveric Study

Introduction: The lumbosacral plexus is a complex network of nerves originating from the lumbar and sacral spinal segments. The nerves of the lumbosacral plexus play a key role in lower extremity motor and sensory functions. Injury to the lumbosacral plexus can be debilitating to patients and cause pain, weakness, and sensory changes in the lower back and limb. Unlike the well-established success of nerve transfer procedures for brachial plexus injuries, interventions for lumbosacral plexus injuries have had limited success. This disparity led us to determine the feasibility of a new approach for nerve transfer using spinal nerve roots before piercing the dura mater (intradural) and spinal nerves after piercing the dura mater (extradural). We suspect that the challenges encountered in such nerve transfers may stem from anatomical or histological differences between the two pieces of the spinal nerve.

Methods: Cadavers were placed in the prone position and draped appropriately for a spinal cord dissection. After dissecting down to the dura mater, segments of the spinal nerves of the lumbosacral plexus before and after piercing the dura mater were harvested and placed in formaldehyde. The nerve samples were then sectioned into cross sections and hematoxylin and eosin (HE) staining was used to observe the histology of the different samples. Ten total spinal nerve samples were obtained from cadavers.

Results: Analysis of micrography showed minimal significant anatomical or histological differences between the spinal nerve segments situated inside and outside of the spinal dura mater. The only difference observed was that intradural spinal nerve roots were slightly smaller in diameter compared to extradural spinal nerves.

Conclusion : Preliminary results disproved our hypothesis as there were minimal anatomical or histological differences found between the intradural and extradural spinal nerve segments. This suggests that the challenges encountered in nerve transfers for lumbosacral plexus injuries may not be attributed to structural disparities between these nerve segments. Future directions include further staining with an AChE stain to determine fiber composition, specifically counting the number of motor vs sensory nerve fibers, to shed light on functional disparities between the two nerve segments.