Background data:

Lumbar spinal stenosis is the most common indication for spinal surgery among patients older than 65 years. The main aim of surgery is to decompress the neural elements. However, radiological proof of decompression and patient outcomes do not always correlate.

Purpose:

The main aim of this study is to investigate the correlation between spinal canal decompression and patient outcome, by investigating three different parameters of canal dimensions.

Materials and Methods:

16 patients diagnosed with lumbar spinal stenosis based on MRI findings, who received surgery from the same senior spine surgeon, were included in the study. The surgical outcome was assessed using the Oswestry Disability Index (ODI), prior to surgery and at the first follow-up. Preoperative and postoperative MRIs were compared to assess the degree of surgical decompression. The change in the minimum cross-sectional area, and the AP and transverse diameter of the dural sac were noted. Any correlation between the change in canal dimensions and the patient outcome was evaluated.

Results:

Of the three parameters evaluated, only the transverse diameter of the spinal canal showed a significant correlation with improved ODI scores. This correlation still existed after multivariate analysis with regard to normal canal dimensions. The change in cross-sectional area and the AP diameter of the dural sac did not improve the outcome.

Conclusion:

Decompression of the transverse diameter of the spinal canal is related to improved patient outcome following spinal stenosis surgery. It is possible that the main reason for discordance between the radiological findings and the neurogenic symptoms in the literature could be that authors were overlooking several parameters when defining stenosis.

Keywords: Spinal stenosis; Oswestry; decompression; spinal canal diameter.