The preoperative imaging assessment in the endoscopic transforaminal approach for lumbar disc herniation

English Keywords:Lumbar disc herniation  Preoperative imaging assessment  Transforaminal approach

English Abstract:

  【Abstract】 Objectives: To discuss the role of preoperative imaging assessment in surgery potocol for transforaminal lumbar disc herniation. Methods: The imaging data of 191 patients with lumbar disc herniation and treated with endoscopic transforaminal approach was analyzed in our hospital from July 2008 to December 2012. Preoperative radiographic evaluation included the diseased disc segments, the protusion position, the height of iliac crest, the included angle between the line connecting the highest point of the iliac crest to the S1 pedicle medial edge and the horizontal line of the upper edge of S1 vertebra(α), the line connecting under 5mm of the L5 pedicle(the distance from lower edge of the L5 pedicle to the puncture needle) and the highest point of the iliac crest(d), posterior height of intervertebral space(H1), the vertical height of the intervertebral foramen(H2). The intersecting position of d and upper edge of S1 vertebral was divided into three regions: Region 1, the midpoint of L5/S1 intervertebral space and contralateral area; Region 2, the midpoint of L5/S1 intervertebral space(excluding this point) to the S1 pedicle medial edge; Region 3, outside of the S1 pedicle medial edge. The prominent disc segments, the prominent position and H1 and H2 was meassured in all cases. The height of iliac crest, α, d and the intersecting position of d and upper edge of S1 vertebra should be measured additionally in the 85 cases of L5/S1 disc herniation. H1≤4mm and H2≤15mm could be identified as the foraminal stenosis. The number of the 18G puncture needle reaching the targeted surgical area intraoperatively was recorded. Results: The L5/S1 disc herniation was noted in 85 cases(44.50%) and L4/5 or upper in 106 cases(55.50%); the prominent position in the central area, lateral recess area, intervertebral foramen area and outside area of the intervertebral foramen(extreme lateral area) was in 17 cases(8.90%), 146 cases(76.44%), 24 cases(12.57%) and 4 cases(2.09%) respectively; the foraminal stenosis was noted in 9 cases(4.71%). Among 85 cases with L5/S1 disc herniation, the height of iliac crest against the middle 1/3 or upper of L4 vertebral body was noted in 3 cases(3.53%), againsting the lower 1/3 or lower of L4 vertebral body was noted in 82 cases(96.47%); α≤30° was noted in 69 cases(81.18%), 30°<α≤40° was in 16 cases(18.82%); d on the region 1, 2 and 3 was in 68 cases(80.00%), 14 cases(16.47%) and 3 cases(3.53%) respectively. As the height of iliac crest against the L5 vertebral body or lower, the average number of puncture was 16 times(12-41 times). When againsting the lower 1/3 of L4 vertebral body to the intervertebral space of L4/5, the average number of puncture was 29 times(16-46 times). When againsting the middle 1/3 or upper of L4 vertebral body, the average number of puncture was 39 times(36-44 times). Conclusions: The height of iliac crest, α, d and the intersecting position of d and upper edge of S1 vertebra mainly affect the operating segments in L5/S1. For the operating segments in the L4/5 and above, the 18G puncture needle can be punctured horizontally irresponsible to the above radiographic factors. The herniated disc segments and position, H1 and H2 affect all the operating segments.