Grade each of the three zones at each level on axial T2 — central canal (Schizas or similar), lateral recess, foramen — and name the structures causing it; the level and zone match the patient's claudication or radiculopathy.
Orient first
- Central stenosis causes neurogenic claudication; lateral recess and foraminal stenosis cause radiculopathy.
- Degenerative spondylolisthesis at L4–5 is a common cause.
- Imaging stenosis is frequent in asymptomatic older people; correlate the level with the symptoms.
Acquire the study
- Lumbar spine MRI: sagittal T1 and T2, axial T2 through each disc level, parasagittal views of the foramina.
The manoeuvre
- Axial T2 at each disc level: central canal — CSF around the rootlets, morphological grade A–D (Schizas), dural sac area in mm² where measured.
- Lateral recess: compression of the descending root.
- Sagittal T1 of the foramina: perineural fat obliteration and root deformation.
- Causes: disc bulge, facet hypertrophy, ligamentum flavum thickening, synovial cyst, spondylolisthesis in mm.
- Conus level and redundant nerve roots above a tight stenosis.
What confirms it
- Stenosis at the level and zone that matches the clinical syndrome.
What licenses you to exclude it
- CSF around the rootlets and perineural fat in every foramen exclude significant stenosis.
The classic misread
- Reporting "multilevel degenerative change" without grading each zone.
- Missing a synovial cyst in the lateral recess.