Clinical Findings

• 
  

  A 54-year-old man presented with right buttock and leg pain and weakness of the right quadriceps.

  
  
• 
  

  A femoral stretch test was positive.

  
  
• 
  

  The diagnostic imaging included magnetic resonance imaging (MRI) and computed tomographic (CT) scans.

  
  
• 
  

  MRI showed a slightly downward-migrated disk herniation at the L1-L2 level compressing the thecal sac and traversing nerve root (TNR) ( Fig. 18.1 ).

  
  
• 
  

  The CT scan showed a soft disk herniation at the L1-L2 level ( Fig. 18.2 ).

Preoperative Plan

• 
  

  The lines for measurement guidance are drawn as described in chapter 15. At upper levels, the angle of the intended needle trajectory line is relatively steep and the annular puncture site is also kept at the midpedicular level to increase the margin of safety.

  
  
• 
  

  The skin entry point should lie closer to the midline (8.6 cm in this case) for an upper lumbar disk herniation than for a lower lumbar herniation (12 to 14 cm) ( Fig. 18.3 ).

Surgical Procedures

1. 
   

   A radiculogram is performed before penetrating the annulus to highlight the path of the nerve root. The tip of the needle is placed at the midpedicular line ( Fig. 18.4 ).

   
   
2. 
   

   The tip of the working cannula is placed midway between the pedicle and the spinous process in the anteroposterior (AP) view ( Fig. 18.5 ). At the same location, the cannula lies in the posterior annulus and nucleus pulposus ( Fig. 18.6 ). Note the difference in the cannula tip’s position from that for the lower lumbar levels, where the cannula tip is kept only in the posterior annulus. After removal of the fragments, one can check for the free course of the nerve root with the flexible bipolar probe ( Fig. 18.7).