Lateral Recess Stenosis¶

Definition¶

Lateral recess stenosis is narrowing of the lateral recess — the space between the posterior aspect of the vertebral body/disc (anterior), the pedicle (lateral), and the superior articular process of the facet joint (posterior). It compresses the traversing nerve root before it exits through the neural foramen.

Anatomy¶

The lateral recess (also called the subarticular zone or Lee zone) is bounded by:

Anterior: posterior vertebral body and disc margin
Lateral: medial wall of the pedicle
Posterior: superior articular process (SAP) of the facet joint and ligamentum flavum

Normal Dimensions¶

AP depth: normally ≥5 mm
Stenosis: <3 mm indicates significant lateral recess stenosis

Causes¶

Facet hypertrophy — the most common cause; the superior articular process encroaches on the lateral recess from posteriorly
Disc herniation — paracentral disc material narrows the lateral recess from anteriorly
Ligamentum flavum hypertrophy — contributes to narrowing from posterolaterally
Osteophytes — from the vertebral endplate or facet margin

Imaging Findings¶

CT¶

Best modality for measuring the bony lateral recess depth
SAP hypertrophy encroaching on the recess
AP depth <3 mm on axial images at the level of the pedicle

MRI¶

Axial T2: nerve root compressed between disc/vertebral body anteriorly and facet posteriorly
The traversing root may appear flattened, displaced, or edematous
Look at the level of the disc and the inferior pedicle — this is where the lateral recess is tightest

Clinical Pearl

Lateral recess stenosis often occurs at a different level than central stenosis in the same patient. It is a common cause of radiculopathy that can be missed if the radiologist only reports central canal measurements. A patient may have a capacious central canal but severe lateral recess narrowing from facet hypertrophy compressing a single traversing nerve root. Always evaluate the lateral recess separately from the central canal on axial images.

Key Points¶

The lateral recess contains the traversing nerve root between the disc (anterior) and facet (posterior)
AP depth <3 mm indicates significant stenosis
Facet hypertrophy is the most common cause
Can cause radiculopathy even when the central canal is not significantly stenotic
CT is best for bony measurements; MRI for nerve root assessment

References¶

Lee CK, Rauschning W, Glenn W. Lateral lumbar spinal canal stenosis: classification, pathologic anatomy and surgical decompression. Spine (Phila Pa 1976). 1988;13(3):313-320. PMID: 3388117. https://pubmed.ncbi.nlm.nih.gov/3388117/
Steurer J, Roner S, Gnannt R, Hodler J; LumbSten Research Collaboration. Quantitative radiologic criteria for the diagnosis of lumbar spinal stenosis: a systematic literature review. BMC Musculoskelet Disord. 2011;12:175. PMID: 21798008. https://pmc.ncbi.nlm.nih.gov/articles/PMC3161920/
Splettstößer A, Khan MF, Zimmermann B, et al. Correlation of lumbar lateral recess stenosis in magnetic resonance imaging and clinical symptoms. World J Radiol. 2017;9(5):223-229. PMID: 28634513. https://pmc.ncbi.nlm.nih.gov/articles/PMC5441455/
Kuittinen P, Sipola P, Aalto TJ, et al. Correlation of lateral stenosis in MRI with symptoms, walking capacity and EMG findings in patients with surgically confirmed lateral lumbar spinal canal stenosis. BMC Musculoskelet Disord. 2014;15:247. https://pmc.ncbi.nlm.nih.gov/articles/PMC4112604/
Subarticular zone stenosis. Radiopaedia.org. https://radiopaedia.org/articles/subarticular-zone-stenosis
Lateral Recess Stenosis. Radiology Key. https://radiologykey.com/lateral-recess-stenosis/