title: Avoiding abdominal flank bulge after anterolateral approaches to the thoracolumbar spine: cadaveric study and electrophysiological investigation.
abstract: OBJECTIVE
  The thoracolumbar junction is frequently accessed through an anterolateral approach with the incision and muscle dissection extending from the lower thoracic region to the lateral border of the rectus abdominis muscle. This approach is frequently associated with the subsequent development of an unsightly and uncomfortable relaxation of the ipsilateral abdominal wall, or flank bulge, caused by denervation injury to the intercostal nerves. However, the etiology of this complication is not widely recognized by spine surgeons. The object of this study was to better define the relevant anatomy and innervation of the anterolateral abdominal wall musculature.
  
  
  METHODS
  The authors performed 32 cadaveric dissections and 6 intraoperative electromyography (EMG) evaluations.
  
  
  RESULTS
  The cadaveric dissection studies and intraoperative EMG evaluations provided detailed anatomy of the anterolateral abdominal wall and its innervation. Cadaveric dissections revealed that the most significant intercostal nerve contributions to the anterolateral abdominal wall arise from T11 and T12. Electrophysiological confirmation of these findings was accomplished through intraoperative stimulation in 6 patients undergoing anterolateral retroperitoneal approaches to the thoracolumbar junction. The authors confirmed T11 and T12 innervation of the anterolateral abdominal wall musculature by direct intraoperative EMG recording in all 6 patients.
  
  
  CONCLUSIONS
  The authors classified the 3 potential zones of injury that can be affected during an anterolateral approach to the thoracolumbar junction. Modifications to the operative technique are suggested to avoid the complication of flank bulge. The most significant intercostal nerve contributions to the anterolateral abdominal wall arise from T11 and T12.
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Fahim
authors.forename: Sang Don
authors.initials: SD
authors.lastname: Kim
authors.forename: Dosang
authors.initials: D
authors.lastname: Cho
authors.forename: Sangkook
authors.initials: S
authors.lastname: Lee
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Kim
mesh_terms: D000009:Abdominal Muscles / Q000294:innervation; D034861:Abdominal Wall / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D004576:Electromyography; D005260:Female; D006801:Humans; D007367:Intercostal Nerves / Q000293:injuries; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D019637:Orthopedic Procedures / Q000009:adverse effects*; D059348:Peripheral Nerve Injuries / Q000517:prevention & control*; D011183:Postoperative Complications / Q000517:prevention & control*; D013904:Thoracic Vertebrae / Q000601:surgery*