Microsurgical extraforaminal decompression of lumbar root canal stenosis.

OBJECTIVE

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.

INDICATION

Single level radiculopathy in degenerative scoliosis or in degenerative disc disease without segmental instability.

CONTRAINDICATIONS

Scoliosis > 30° at the index level, lateral listhesis > 6 mm, mobile vertebral slip.

SURGICAL TECHNIQUE

Microscope from skin to skin. A 35-mm skin incision about 40 mm 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.

POSTOPERATIVE MANAGEMENT

Same day mobilization.

RESULTS

The clinical results in 22 cases (15 men) 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 64 years (range 50-82 years). An independent follow-up examination was performed 3 months and 1 year following surgery. The mean FU was 27 months (range 41-22 months). 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.