Disc herniation

• displacement of disc material beyond limits of intervertebral disc space
• what is disc material? cartilage, nucleus, fragmented annular tissue and apophyseal bone
• break in vertebral end plates or disruption in annulus fibrosus needed for herniation to occur

TYPES

extrusion

• base against the disc is smaller than diameter of displaced disc material (measured in same plane ax or sag)

protrusion

• base of disc is broader than any other diameter of displaced disc material

focal

• <25% of disc circumference involved

broad based

• 25%-50% of disc circumference involved

sequestered disc / free fragment

• no connection between disc and displaced disc material
• migration is the more commonly used term

contained herniation

• displacement of disc material covered by annulus fibrosus