Neuroimaging Study And Clinical Cases Analysis Of The XLIF Approach For Lumbar 4/5 Intervertebral Disc Degeneration

Objective Extreme lateral interbody fusion(XLIF)has a higher risk of nerve injury in the treatment of L4/5 segments.The relative position of the lumbosacral plexus and the intervertebral space of the L4/5 segment was observed by using the enhanced 3D SPACE STIR sequence to scan the lumbosacral plexus to further explore the safety of XLIF in the treatment of L4/5 segments and to reduce the incidence of nerve injury.Methods The first Part(Part I): From January 2015 to December 2016,30 patients with lumbosacral plexus nerve were scanned by 3D SPACE STIR sequence for lumbar degenerative disease.There were 15 males and 15 females with an average age of 48 years(23-68 years old),obtained the enhanced 3D SPACE STIR sequence original image of these patients with lumbar degenerative disease.According to Moro’s vertebral space partition method,the lumbar 4/5 segment sagittal intervertebral space plane was divided into four zones: I,II,and IV.Based on the enhanced 3D SPACE STIR sequence image of SIEMENS workstation,we simulated the surgical approach of L4/5 segment XLIF,and observed the distribution of lumbar plexus in the L4/5 segment of the intervertebral space on the left and right sides,and recorded the frequency of the lumbar plexus.The second part(Part Ⅱ): The study has collected 10 patients who had been diagnosed with lumbar degenerative disease in Nan Shan hospital from January 2015 to December 2017,in which there were 6 males and 4 females,with average age 52 years old(29-68 years old).All patients underwent preoperative enhanced 3D SPACE STIR sequence scanning of the lumbosacral plexus and combined with the results of the first part to evaluate the relative positional relationship between the L4/5 segment and the XLIF work channel.After the zone II was confirmed that there was no nerve distribution,the XLIF operation of this L4/5 segment was performed and the incidence of postoperative nerve injury was recorded.Results(1)In 30 patients,the distribution frequency of lumbosacral plexus in the L4/L5 segment of the intervertebral space was that: there were 30 cases in zone IV,30 in zone III,5 in zone II,1 in zones I on the left side;there were 30 cases in zone IV,,30 in zone III,8 in zone II,0 in zones I on the right side.The distribution of lumbosacral plexus in the psoas muscle of the left and right sides of the L4/5 segment is dense in zone III and zone IV,with a gradual decrease or disappearance from zone III to I.zone I and II are the relative “naked regions” of the nerves.There was some individual difference in the distribution of nerves in the psoas muscles on the left and right sides,but the difference was not statistically significant.(2)There were 10 cases in XLIF surgical group and all the operations were assisted lateral and posterior pedicle screw fixation in operation.The average amount of bleeding was 50 ml,and the average operation time was 80 minutes(60-180 minutes).The average length of incision was 4cm(3.5-4.5cm)and the average hospitalization time was 9 days(7-14 days)after operation.There were 4 cases of patients with iliopsoas muscle strength decreased slightly(4 weeks back to normal);1 cases of fusion sinking,although the intervertebral height decreased,but no obvious symptoms.No postoperative sensory loss or dyskinesia occurred in the thigh after operation.The mean follow-up time was four months.The scores of VAS and ODI were significantly improved at the time of one month,3 months after operation and the last follow-up,compared with the scores before operation.Conclusion The distribution of lumbosacral plexus in the psoas muscle of the left and right sides of the L4/5 segment is dense,with a gradual decrease or disappearance from zone III to I.zone I and II are the relative “naked regions” of the nerves.Zone II is a "relative safety zone" for the XLIF approach of the L4/5 segment,but it is not absolutely safe.The lumbosacral plexus-enhanced 3D SPACE STIR sequence scan before the XLIF surgery of the L4/5 segment can help to assess the relationship of the surgical channel and the lumbosacral plexus nerve.When the nerve "bare area" of the L4/5 segment--Zone II disappears,it is high risk for the XLIF surgery of the L4/5 segment.At this time,the choice of XLIF should be abandoned,and Change other surgical methods for L4/5 segment to reduce the incidence of nerve damage.