Anatomical Study And Clinical Significance Of Lumbar Autonomic Nerves

Background:Anterior lumbar interbody fusion(ALIF)is a commonly used surgical technique for the treatment of traumatic or degenerative lumbar disc diseases.Lumbar autonomic nerve injury is a serious complication in anterior lumbar surgery.However,clinicians do not have a deep understanding of the anatomical characteristics of lumbar autonomic nerves,which limits its development and application.Purpose:This study was designed to investigate the anatomical characteristics of lumbar autonomic nerves and provide a better understanding of these nerves for anterior lumbar spinal surgery.Methods:A total of 10 embalmed male cadavers(age range,36-78 years old;mean age,56 years old;without any evidence of pathology)were used for the study.Abdominal organs were carefully removed,and lumbar vertebrae were exposed.The superior hypogastric plexus,abdominal aortic plexus,inferior mesenteric plexus,lumbar sympathetic trunks,and lumbar splanchnic nerves were exposed,and the overlying loose connective tissue and nearby adipose tissue were meticulously removed.A digital caliper(accurate to 0.01 mm)was used to measure the distance between the initial sites of the lumbar splanchnic nerves and the corresponding lumbar vertebral inferior endplate,the distance between the ipsilateral and adjacent lumbar splanchnic nerves,the distance between the anterior margin of the vertebral body and the posterior margin of the lumbar sympathetic trunk in the sagittal plane,the distance between anterior margin of the lumbar intervertebral disc and the anterior margin of the lumbar intervertebral foramen in the sagittal plane,the length and width of the trunk of the superior hypogastric plexus,and the distance between the right margin of the superior hypogastric plexus and the median line at the L5/S1 level.The angles formed by the lumbar splanchnic nerves and the vertical axis were also measured.This study has been supported by grants from Science and Technology Planning Project of Guangdong Province(CN)(Grant No.2017B020210010)without potential conflict of interest-associated biases in the text of the paper.Results:In this study,a total of 72 lumbar splanchnic nerves were identified in the 10 human cadavers.On average,the initial sites of the first,second,third,and fourth lumbar splanchnic nerves were 9 mm distal,5 mm distal,9 mm proximal,and 9 mm distal to the inferior endplates of the LI,L2,L3,and L4 vertebrae,respectively,with variations from 6 to 11 mm for each nerve among specimens.There were differences in the distributions of the locations of the initial sites of the lumbar splanchnic nerves(F=20.057,p=0.000).The distribution of the location of the initial site of the third lumbar splanchnic nerve was different from that of the other lumbar splanchnic nerves(p=0.000).The distribution of the location of the initial site of the first lumbar splanchnic nerve was not different from that of the second and fourth lumbar splanchnic nerves,and the distribution of the location of the initial site of the second lumbar splanchnic nerve was also not different from that of the fourth lumbar splanchnic nerve,and the distribution of the initial sites of left lumbar splanchnic nerves was also no different from that of the associated right lumbar splanchnic nerves(p>0.05).The distance between the first and the second lumbar splanchnic nerves,the second and the third lumbar splanchnic nerves,or the third and the fourth lumbar splanchnic nerves were 24±6 mm,22±8 mm,and 5 5± 11 mm,respectively.The bilateral lumbar sympathetic trunks(N=57,95%)were more likely to be located in the first third of the sagittal plane at the level of the L2/3,L3/4,and L4/5 intervertebral discs.The superior hypogastric plexus trunks were approximately 60±7 mm in length,11 ±6 mm,and 14±4 mm in width from the top down and were located in front of the aortic bifurcation,fifth lumbar vertebra,and sacral promontory and between the left and right common iliac artery.In the plane containing the inferior endplate of the L5 vertebra,the right margin of the superior hypogastric plexus was located 4±3 mm to the left of the median line;in the plane containing the superior endplate of the S1 vertebra,the right margin of the superior hypogastric plexus was 5±3 mm to the right of the median line.There was no significant difference in the angles between each lumbar splanchnic nerve and the vertical axis(H=2.461,p=0.482),and the average angle was approximately 50°±6°.The angle formed by the left lumbar splanchnic nerves and the vertical axis was also no different from that of the associated right lumbar splanchnic nerves(p>0.05).Conclusions:In this study,the same number and parallel courses of lumbar splanchnic nerves were found on each side.The initial sites of 80.6%lumbar splanchnic nerves were superior to the inferior endplate of the L3 vertebra.The distances between the initial site of the third and the fourth lumbar splanchnic nerves were much larger than that between the other two adjacent lumbar splanchnic nerves.And at the right-extra side of the L5/S1 levels,very thin nerve fiber of the superior hypogastric plexus could be distinguished.