Kristen Scheitler, MD

Kristen Scheitler, MD



1/ Have you ever had a patient with low back pain & degenerative findings on lumbar MR imaging? 🔎👀 Demystifying lumbar stenosis is one of my favorite things to teach medical students & junior residents! A thread 🧵

2/ Let’s review the normal anatomy of the L3-4 spinal segment. 🟡 Mid-sagittal: we see the central canal w/ the thecal sac, containing nerve roots distal to the conus. 🟠 Parasagittal: the lumbar nerve roots exit below their respective pedicles via the neural foramina.

3/ Normal anatomy cont’d: 🔵 Posterior view: we see the relationship between “exiting” nerve roots & their respective pedicles, as well as “traversing” nerve roots. ⚪️ Axial (simplified): shows the relationship between the disc, thecal sac, root, and joint.

4/ “Lumbar stenosis” refers to anything that decreases the area of: ▫️central canal (thecal sac) ▫️lateral recess ▫️neural foramen Correspondingly, we classify pathologies anatomically as causing “central,” “lateral recess,” or “foraminal” stenosis (color-coded below).

5/ Central stenosis 🟰 compression of the thecal sac by any central pathology (central disc herniation, yellow ligament hypertrophy, epidural lipomatosis, &c). Primary symptoms: 🔻neurogenic pseudoclaudication 🔻traversing (L4) nerve root radicular pain/numbness/or weakness

6/ Lateral recess stenosis 🟰 compression in the area bound by the pedicle, vertebral body, & superior articular process…basically the area containing the first part of the exiting root (L3). Most common symptoms: 🔻exiting (L3) nerve root radicular pain/numbness/or weakness

7/ Foraminal stenosis = compression of the exiting nerve root in the foramen, distal to the lateral recess. Common causes include lateral disc herniation, joint hypertrophy, spondylolisthesis, &c. Main symptoms: 🔻exiting (L3) nerve root radicular pain/numbness/or weakness

8/ SUMMARY: Lumbar stenosis has many causes & is classified anatomically. Each classification has corresponding implications for symptom localization & treatment! Disclaimer: content was simplified for purposes of conceptualization. Any comments or extra info welcomed :)

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