Spinal Canal Stenosis

spinal canal stenosis

This 65 year-old female patient had a long history of L3-L4 spinal canal stenosis (previously imaged). A follow-up study was performed.

The midline sagittal T2-weighted MRI shows bunched and wavy cauda equina above the L3-L4 stenosis, and straight cauda equina below it. There are disc herniations at L3-L4, L4-L5 and L5-S1. There is loss of disc high signal consistent with degenerative dessication. Axial images through L3-L4 showed the stenosis to be due to a combination of posterior disc herniation, facet joint hypertrophy and ligamentum flavum hypertrophy.

Lumbar spinal stenosis may be congenital or acquired, or both (as in congenital short pedicles with superimposed degenerative disease). The symptoms include: low back pain; “spinal claudication” – lower limb pain, numbness and weakness, worse during walking or standing; or cauda equina syndrome – paraparesis, incontinence, saddle anaesthesia and hyporeflexia.

Radiological findings include: a sagittal diameter of the canal of less than 16mm; reduced CSF and crowding of nerve roots; hourglass configuration on sagittal view; triangular or trefoil shape on axial view; redundant serpiginous nerve roots above or below the stenosis; hypertrophy of articular processes, pedicles, laminae, ligaments; and disc bulges or herniations.

Not all spinal stenoses are symptomatic, and careful clinical correlation is required before treatment (generally operative) is considered.

Reference: Dahnert W. Radiology Review Manual. Lippincott, Williams & Wilkins 5th edition, 2003.

Credit: Dr Laughlin Dawes