Lumbar intervertebral disc protrusion to the rear 4mm is not a very serious disease, according to the severity of lumbar intervertebral disc protrusion is divided into 3 kinds: 1, lumbar disc bulging, lumbar disc bulging from 1-5mm or so ranging. 2, lumbar disc protrusion, lumbar disc protrusion is more serious, it can reach more than 5mm. 3, lumbar intervertebral disc prolapse, at this time is not the protruding of the intervertebral disk, but intervertebral disk completely from the vertebral space to the vertebral canal to produce obvious compression of the nerve. The lumbar intervertebral disc herniation is no longer a herniated disc, but the intervertebral disc completely falls out of the intervertebral space into the vertebral canal, and produces obvious pressure on the nerve. So lumbar disc herniation 4mm is not very serious, belongs to the relatively light disease.