"grade 0: (no stenosis) no narrowing of the spinal canal"
"grade 1: (mild stenosis) obliteration of more than 50% of the subarachnoid space without any sign of cord deformity"
"grade 2: (moderate stenosis) central spinal canal stenosis with spinal cord deformity but no spinal cord signal change"
"grade 3: (severe stenosis) increased T2 signal intensity of the spinal cord at the level of compression"