Table 1 Classification of lumbar foraminal stenosis as proposed by Lee et al.⁶.

0: no foraminal stenosis

No perineural fat obliteration

1: mild foraminal stenosis

Perineural fat obliteration in vertical or transverse direction

No evidence of morphologic change in nerve root

2: moderate foraminal stenosis

Perineural fat obliteration in all four directions

No evidence of morphologic change in nerve root

3: severe foraminal stenosis

Nerve root collapse or morphologic change