Clinical Findings

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  A patient presented with right posterior leg pain that had lasted for 5 months.

  
  
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  The patient exhibited a positive femoral stretch test and decreased motor power in plantar extension.

  
  
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  Preoperative imaging showed a soft disk herniation at the L5-S1 level compressing the thecal sac and traversing the nerve root ( Fig. 18.91 ).

Preoperative Plan

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  The lines for measurement guidance are drawn as described in previous cases.

  
  
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  The skin entry point for lower lumbar disk herniation lies further from the midline (12.1 cm in this case) as compared with the upper lumbar herniation (6 to 9 cm) ( Fig. 18.92 ).

  
  
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  The needle should be at a slightly cranial to caudal angle.

Surgical Procedures

1. 
   

   The needle tip is located at the midline on the AP view and at the posterior vertebral body line at the lateral view. This is a safe needle position in this case because the extruded disk is retracting the thecal sac and TNR posteriorly ( Fig. 18.93A,B ).

   
   
2. 
   

   A beveled working cannula tip is in the paramedian location of the disk to remove the main component of the herniation ( Fig. 18.93C,D ).

Endoscopic Findings

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  On introduction of the endoscope the epidural fat, overhanging LF, facet joint capsule, and base of the blue-stained herniated disk tissue are visualized ( Fig. 18.94A ).

  
  
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  Some of the disk tissue is removed with the grasping forceps to create a working space. After this, the herniated fragment can be seen above the annulus and moving into the epidural space through the annular opening ( Fig. 18.94B ).

  
  
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  The annular tear site is then seen ( Fig. 18.94C ).

  
  
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  The fibers of the annulus and some strands of epidural fat tissue can be identified after the central disk is removed with the side-firing laser ( Fig. 18.94D ).

  
  
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  After removal of the herniated disk, the decompressed TNR is noted ( Fig. 18.94E ).

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  The completely decompressed TNR and thecal sac are observed after further removal of the central extruded disk ( Fig. 18.94F ).