Table 2.

Classification of Disc Degeneration by Pfirrmann: grading scale used to assess the severity of degenerative changes within the nucleus of the disc. As the Pfirrmann classification states, grade I disc has a uniform high signal in the nucleus on T2-weighted images, grade II shows a central horizontal line of low signal intensity on sagittal images, grade III shows high intensity in the central part of the nucleus with lower intensity in the peripheral regions, grade IV shows low signal intensity centrally and blurring of the distinction between nucleus and anulus, and grade V shows homogeneous low signal with no distinction between nucleus and anulus.

Grade	Structure	Distinction of Nucleus and Anulus	Signal Intensity	Height of Intervertebral Disc
I	Homogeneous, bright white	Clear	T2-w Hyperintense, isointense to cerebrospinal fluid	Normal
II	Inhomogeneous with or without horizontal bands	Clear	T2-w Hyperintense, isointense to cerebrospinal fluid	Normal
III	Inhomogeneous, gray	Unclear	Intermediate	Normal to slightly decreased
IV	Inhomogeneous, gray to black	Lost	Intermediate to hypointense	Normal to moderately decreased
V	Inhomogeneous, black	Lost	hypointense	Collapsed disc space