Table 1.

The classification of Pfirrmann disc degeneration grade

Grade	Structure	Distinction of nucleus and anulus	Signal intensity	Height of Intervertebral disc
1	Homogeneous, bright white	Clear	Hyperintense, isointense to cerebrospinal fluid	Normal
2	Inhomogeneous with or without horizontal bands	Clear	Hyperintense, isointense to cerebrospinal fluid	Normal
3	Inhomogeneous, gray	Unclear	Intermediate	Normal to slightly decreased
4	Inhomogeneous, gray to black	Lost	Intermediate to hypointense	Normal to moderately decreased
5	Inhomogeneous, black	Lost	Hypointense	Collapsed

Grade 1, normal shape, no horizontal bands, clear distinction of nucleus and annulus; grade 2, nonhomogeneous shape with horizontal bands, some blurring between nucleus and annulus; grade 3, nonhomogeneous shape with blurring between nucleus and annulus, annulus shape still recognizable; grade 4, nonhomogeneous shape with hypointensity, annulus shape not intact and distinction between nucleus and annulus impossible, disc height usually decreased; grade 5, same as grade 4 but with collapsed disc space.