Microsurgical extraforaminal decompression of lumbar root canal stenosis

Abstract

To decompress the lumbar spinal nerve impinged peripherally to the lateral recess. To avoid in selected cases the pedicle screw fixation and fusion of the segment. Single level radiculopathy in degenerative scoliosis or in degenerative disc disease without segmental instability. Scoliosis > 30° at the index level, lateral listhesis > 6mm, mobile vertebral slip. Microscope from skin to skin. A 35-mm skin incision about 40mm off the midline. Transmuscular access by blunt splitting of the paravertebral muscles pointing about 40° towards the midline. Insertion of an expandable tubular retractor or of a speculum counter retractor system. Dissection of the target lumbar nerve in the midst of the extraforaminal fat tissue. Enlargment of the root canal mostly by drilling and using thin foot plate punches. The nerve is decompressed from peripherally to the lateral rim of the yellow ligament. Closure by layers. Drainage is usually not required. Same day mobilization. The clinical results in 22cases (15men) of extraforaminal nerve root involvement were studied. Because of the very selective indication the patients were recruited over a 3-year time-span. The mean age was 64years (range 50-82years). An independent follow-up examination was performed 3months and 1year following surgery. The mean FU was 27months (range 41-22months). According to the modified MacNab criteria, the results were excellent (45%), good (23%), fair (14%), and poor (18%). Four patients underwent second surgery for pedicle screw fixation and fusion. Persistent low back pain was the most common cause of an unsatisfactory postoperative course.