Lumbar spinal stenosis is a degenerative condition characterized by narrowing of the lumbar spinal canal due to 

• bony structures

  • facet osteophytes

  • uncinate spur (posterior vertebral body osteophyte)

  • spondylolisthesis

• soft tissue structures

  • herniated or bulging discs

  • hypertrophy or buckling of the ligamentum flavum 

  • synovial facet cysts

Most common reason for lumbar spine surgery in patients > 65 years old

Most commonly occurs at L4-5 (91%)

Symptoms 

• back pain 

• referred buttock pain

• leg pain , often unilateral

• neurogenic claudication

  • pain worse with extension (walking, standing upright) 

  • pain relieved with flexion (sitting, leaning over shopping cart, sleeping in fetal position) 

• weakness

• bladder disturbances : recurrent UTI present in up to 10% due to autonomic sphincter dysfunction

• cauda equina syndrome (rare)

Physical exam 

• Kemp sign : unilateral radicular pain from foraminal stenosis made worse by back extension

• straight leg raise (tension sign): usually negative

• Valsalva test: radicular pain not worsened by Valsalva as is the case with a herniated disc

• normal neurologic exam : patients may have no focal deficits, as exam often takes place with patient seated and symptoms may be reproducible or exacerbated only with lumbar extension or ambulation

Imaging

• Xray: osteophytes, narrowing, spondylolisthesis, scoliosis…..

• MRI: central stenosis with a thecal sac <100mm2

• CT Scan: bony abnormality, hypertrophied facets….

Treatment

• Oral medications, physical therapy, and corticosteroid injections

• wide pedicle-to-pedicle decompression

• wide pedicle-to-pedicle decompression with instrumented fusion If:

  • segmental instability (isthmic spondylolisthesis, degenerative spondylolisthesis, degenerative scoliosis)

  • surgical instability created by complete laminectomy and/or removal of > 50% of facets