Lumbar Spinal Stenosis
Lumbar spinal stenosis (LSS) is narrowing of the lumbar spinal canal, which puts pressure on the cord or sciatic nerve roots before their exit from the foramina. It causes positional back pain, symptoms of nerve root compression, and lower-extremity pain during walking or weight bearing.
(See also Evaluation of Neck and Back Pain.)
Spinal stenosis can be congenital or acquired. It may involve the cervical or lumbar spine. Acquired LSS is a common cause of sciatica in middle-aged or elderly patients. The most common causes of LSS are osteoarthritis, degenerative disk disorders, spondylosis, and spondylolisthesis with compression of the cauda equina. Other causes include Paget disease of bone, rheumatoid arthritis, and ankylosing spondylitis.
Pain occurs in the buttocks, thighs, or calves during walking, running, climbing stairs, or even standing. The pain is not relieved by standing still but by flexing the back or by sitting (although paresthesias may continue). Walking up hills is less painful than walking down because the back is slightly flexed. Patients may have pain, paresthesias, weakness, and diminished reflexes in the affected nerve root distribution. Rarely, spinal cord compression may cause cauda equina syndrome.
Spinal stenosis is suspected based on characteristic symptoms. Diagnostic tests are the same as for sciatica (see Sciatica : Diagnosis). Calf symptoms may simulate those of intermittent claudication. Claudication can be differentiated by relief with rest (not position change), skin atrophy, and abnormalities in pulses, capillary refill, and vascular tests.
Conservative treatments and indications for surgery are similar to those for sciatica. For advanced spinal stenosis, surgery involves decompression of nerve root entrapment by vertebral canal and foraminal encroachments, which sometimes requires laminectomy at 2 or 3 levels plus foraminotomies.
Spinal stability must be preserved. Spinal fusion may be indicated if there is instability or severe, well-localized arthritic changes in 1 or 2 vertebral interspaces.