Clinical Findings

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  A 63-year-old woman presented with a sudden onset of severe left gluteal pain having lasted 1 week.

  
  
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  Paresthesia in the left L4 and L5 dermatomes with decreased left knee jerk were observed.

  
  
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  Preoperative MRI showed a foraminal disk herniation that was slightly upward migrated at L4-L5. The nerve root had been pushed upward and to the posterior by the herniated fragment ( Fig. 18.82 ).

  
  
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  Such acute disk ruptures in contact with the dorsal root ganglion are extremely painful and usually do not respond favorably to conservative treatment.

Preoperative Plan

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  The target point is identified at the posterolateral corner of the annulus on an axial MRI.

  
  
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  The intended trajectory is drawn, and the distance from the midline and angle of approach is determined.

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  This patient can be better managed with a targeted fragmentectomy by a foraminal approach instead of a transforaminal one.

  
  
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  The skin entry point is much more medial (11.5 cm from the midline) than that for a routine transforaminal approach for intracanalicular herniation, and the angle of approach is also quite steep ( Fig. 18.83 ).

  
  
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  If a routine transforaminal approach is used in this case, the exiting nerve root could be injured or the procedure might be more painful for the patient because the nerve root has been pushed posterolaterally.