Elsevier

World Neurosurgery

Volume 105, September 2017, Pages 519-525
World Neurosurgery

Original Article
Injury to the Lumbar Plexus and its Branches After Lateral Fusion Procedures: A Cadaver Study

https://doi.org/10.1016/j.wneu.2017.06.027Get rights and content

Introduction

Neurologic deficits from lumbar plexus nerve injuries commonly occur in patients undergoing lateral approaches. However, it is not yet clear what types of injury occur, where anatomically they are located, or what mechanism causes them. We aimed to study 1) the topographic anatomy of lumbar plexus nerves and their injuries in human cadavers after lateral transpsoas approaches to the lumbar spine, 2) the structural morphology of those injuries, and 3) the topographic anatomy of the lumbar plexus throughout the mediolateral approach corridor.

Methods

Fifteen adult fresh frozen cadaveric torsos (26 sides) underwent lateral approaches (L1-L5) by experienced lateral spine surgeons. The cadavers were subsequently opened and the entire plexus dissected and examined for nerve injuries. The topographic anatomy of the lumbar plexus and its branches, their injuries, and the morphology of these injuries were documented.

Results

Fifteen injuries were found with complete or partial nerve transections (Sunderland IV and V). Injuries were found throughout the mediolateral approach corridor. At L1/2, the iliohypogastric, ilioinguinal, and subcostal nerves were injured within the psoas major muscle, the retroperitoneal space, or the outer abdominal muscles and subcutaneous tissues. Genitofemoral nerve injuries were found in the retroperitoneal space. Nerve root injuries occurred within the retroperitoneal space and psoas muscle. Femoral nerve injuries were found only within the psoas major muscle. No obturator nerve injuries occurred.

Conclusions

Lateral approaches can lead to structural nerve damage. Knowledge of the complex plexus anatomy, specifically its mediolateral course, is critical to avoid approach-related injuries.

Introduction

The lateral transpsoas approach to the lumbar spine is increasingly being used to treat degenerative changes requiring fusion.1 In contrast to conventional posterior spinal fusion techniques, this minimally invasive approach spares extensive posterior tissue dissection and resection for cage implantation and decreases operative time, blood loss, postoperative pain, and tissue trauma.1 Although minimally invasive, this procedure has the approach-related potential to cause lumbar plexus (Figure 1) nerve injuries from the insertion and dilation of dilatators or retractors. Plexus injuries are reported in 6%–33% of cases and often present as neuropathic pain as well as motor or sensory deficits.1, 2, 3

Although neurologic deficits commonly occur, nerve injuries from these approaches have so far only been assessed clinically, leaving the following questions unanswered:

  • 1.

    Where can nerve injuries occur? At what spinal level, anatomic compartment (within the psoas major muscle, retroperitoneal space or subcutaneous tissue), and segment of the nerve?

  • 2.

    What type of nerve injuries can occur? Is there structural damage to the nerve?

  • 3.

    Which nerves, not commonly monitored by electromyography (EMG) or not clearly discernable by clinical assessment, are prone to injury?

  • 4.

    Are there surgical recommendations that could help to preclude these plexus injuries?

To answer these questions, we studied the topographic anatomy of the lumbar plexus nerves and their injuries in human cadavers after expert surgeons had performed lateral fusion procedures in the lumbar spine using standard operative techniques.

Several cadaveric anatomic studies on plexus nerve anatomy for lateral approaches have been reported.4, 5 However, to our knowledge, this is the first anatomic study on cadavers to examine the plexus nerves for possible injuries immediately after standard lateral fusion surgery. Our goal was to study which nerves can be encountered and injured throughout the mediolateral approach corridor, what types of injury can potentially occur, and what mechanisms might be involved.

Section snippets

Methods

We used 15 adult fresh frozen cadaveric torsos (26 sides), 7 male and 8 female, with an average age of 79 years at death (range, 69–88 years). The cadavers had no signs of previous spine, abdominal, or retroperitoneal surgery. No intra-abdominal or retroperitoneal disease was identified.

The surgical procedures were performed during cadaver spine courses. All 5 participating surgeons are recognized experts in lateral access spine surgery. Each level was approached only once, on each side, by the

Results

We assessed 32 lumbar levels. There were 15 injuries among all the lumbar plexus nerves examined. The following results of the injuries are classified by level.

Discussion

The goal of this study was an anatomic assessment of plexus nerve injuries from lateral approaches to the spine. We found that about 50% of all segments operated on had plexus nerve injuries, which occurred at segments L1-L4 and involved nerve roots as well as motor and sensory nerves. In a similar cadaver study, Banagan et al.6 found direct nerve injuries from lateral approaches in 25% of operated segments. The higher percentage in our study could be explained as follows:

First, Banagan et al.6

Conclusions

Lumbar plexus nerve injuries can occur throughout the mediolateral approach to the lumbar spine. Nerve injuries lateral to the psoas major muscle were observed predominantly at L1/L2 and L2/L3 in our study. Structural nerve injuries (Sunderland IV and V) can occur from lateral approaches. These injuries can be classified as intraoperative crush injuries from blunt objects. Awareness of mediolateral anatomic zones and the topographic anatomy of the lumbar plexus nerves within these zones could

Acknowledgments

The authors wish to thank the cadaver donors and their families for allowing their gift to be used for the advancement of science.

References (18)

There are more references available in the full text version of this article.

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    In their cadaveric study, Uribe et al.21 reported that the GFN travels obliquely (posteriorly to anteriorly) in a cephalocaudal direction through the psoas muscle, crossing the disc space of L2-L3 at the middle anterior quarter of the vertebral body and will be potentially vulnerable in a L2-L3 procedure in which the surgical corridor directly intersects the course of the nerve. Grunert et al.23 demonstrated that an LFCN injury and L2 nerve root injury can occur in an experimental L2-L3 LLIF of insertion where both nerves traverse the psoas muscle. A previous study reported that anterior thigh symptoms associated with an L4-L5 procedure were primarily caused by injury to the femoral nerve,21 1 of the nerves subjected to intraoperative neuromonitoring.

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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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