Original ArticleInjury to the Lumbar Plexus and its Branches After Lateral Fusion Procedures: A Cadaver Study
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.
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2020, World NeurosurgeryCitation Excerpt :Literature describing the course of the obturator nerve is variable, with most reporting the nerve traversing within the psoas major before emerging from the medial border of the muscle.12 Less commonly, the nerve has been illustrated11,13 and described14-16 as traveling medial to the psoas major along its entire course. Such regional anatomy is obviously necessary to clarify in the clinical setting of pre- and transpsoas spinal procedures.
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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.