There are a number of non-surgical treatments for lumbar spinal stenosis. Most experts recommend trying other treatments first before surgery. Physical therapy, exercises, chiropractic adjustments, acupuncture, massage and others may be helpful and make surgery unnecessary.The largest study of treatment for lumbar spinal stenosis has just been published in 2010 in the medical journal Spine (SPINE Volume 35, Number 14, pp 1329–1338).
This study compared surgery to non-operative care that included so-called "usual care" consisting of exercises and medication. Patients in this study got at least somewhat better regardless of whether they had surgery or not.
The surgical patients had a bit more more relief, but both groups improved. About 1/2 of the non-surgical patients improved enough that they didn't need to have surgery. Up to 13% of surgical patients had to have yet another operation to relieve their pain.
This study did not examine "alternative" treatments such as chiropractic adjustments, acupuncture or yoga. Most medical guidelines consider the scientific evidence for the effectiveness of these alternative treatments to be inconclusive. However most of these guidelines also note that these treatments are safe and not likely to make the stenosis worse when performed by a competent clinician.
So considering that surgical versus non-surgical care produces similar results, it is reasonable to consider trying ,non-surgical treatments for spinal stenosis first. Consulting with a good chiropractic physician or an acupuncture practitioner is a good choice for a second opinion prior to surgery.