Schizas classification

see https://operativeneurosurgery.com/doku.php?id=lee_classification_for_lumbar_foraminal_stenosis

Grade A: no or minor lumbar spinal stenosis

A1: rootlets lying dorsally and occupying less than half of the dural sac area.

A2: rootlets lying dorsally with a horseshoe configuration

A3: rootlets lying dorsally and occupying more than half of the dural sac area

A4: rootlets lying centrally and occupying the majority of the dural sac area

Grade B: moderate stenosis: rootlets occupying the entire dural sac, but rootlets can still be individualized

Grade C: severe stenosis: no recognizable rootlets with complete effacement of cerebrospinal fluid space, but epidural fat is present posteriorly

Grade D: extreme stenosis: no recognizable rootlets and no epidural fat posteriorly ¹⁾