Table 1.

Sub-types of spinal canal stenosis, which can be alone or combined

Stenosis types (by anatomical site)	Causes	Root affected
Central	Segmental slip in spondylolisthesis, flavum bulging or facet joint hypertrophy, congenital	Descending root
Sub-articular
Foraminal	Bone spurs from facet joints, bulging or herniated discs, ligamentous flavum hypertrophy	Emerging root
Extraforaminal (far lateral)