The patient came to the clinic 20-October-2007 complaining of LBP with left sciatica for 2 years after falling down. Right sciatica took place the last 3 weeks after the mother death. MRI lumbar spine done 04-July-2007 showing LCS L3-4, L4-5 and L5-S1 with spondylolisthesis of L4-5 and extrusion of L5-S1 right side.

On examination: the patient has scoliotic stance with weak dorsi and planterflexion both feet. SLRS was 90 degrees both sides.
The patient was sent for another MRI with MR Myelography of the lumbar spine with dynamic X-ray studies. The same findings were observed and about the overmobility of the L4-5 was not conclusive.
It was explained to the patient and relatives, that the patient needs decompression of the stenosis segments and exploration of the overmobility will be studied during surgery.

Skeletonization of L3 down to the sacrum was performed after putting the patient in ISIS Inomed IOM using pedicle screw scenario. Check for instability of L4-5 was not convincing. Decompressive laminectomy of L4, L5 and partial of L3 and upper rim of the sacrum was performed. The dura was very thin due to severe compression all over the field. Foraminotomy of right S1 root was done and there was a small tear below the axilla due to severe compression, which was stitched using nylon 6 zero. Check for segmental instability was performed several times and inspection of the L4-5 isthmi and the facet joints applying considerable amount of force denied the presence of instability. During the foraminotomy, using MEP protocol, the stimulation threshold of the running roots were ranging from 3-4 mA. Inspection of the L5-S1 extrusion showed that it is very hard and not movable, for what it was decided not to remove the extrusion, nor to use the transpedicular screws for fixation.

Smooth postoperative recovery with normalization of the power of the right foot.

The presence of I-degree of spondylolisthesis is not sufficient to go for transpedicular fixation. Staged check for instability, must be performed in all steps of surgery. If there is suspicion about instability take place, then transpedicular screw fixation is mandatory. Otherwise it is better not to fuse the stable structure.

The presence of ossified extrusion at L5-S1 made it reasonable not to touch the extrusion, since foraminotomy of the right S1 root was sufficient to resolve the problem and in case of disc removal another possibility for recurrence will emerge later.