|The spinal column (vertebral column) is made up of 24 movable bones, or vertebrae (7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae) and 2 fused sections (the sacrum and the coccyx). An intervertebral disc disorder is a protrusion or herniation of one of the gel-like cushions (discs) that separate the vertebrae of the spine. The displaced gel (nucleus pulposus) of the disc may seep through the torn or stretched outer covering of the disc (annulus fibrosus) and press against the spinal nerves or the spinal cord itself, causing changes in sensory, motor, and reflex function (radiculopathy).|
Disc disorders of the upper (cervical), mid (thoracic), and lower (lumbar) spine are discussed separately. See Cervical Disc Disorder with Myelopathy, Thoracic Disc Disorders with Myelopathy, and Lumbar Disc Disorders with Myelopathy for more information.
Incidence and Prevalence: Before age 40, approximately 25% of people show evidence of disc degeneration at one or more levels. Past age 40, more than 60% of people show evidence of disc degeneration at one or more levels on MRI (Furman).
Asymptomatic cervical disc herniation is present in 10% of individuals younger than 40 years and in 5% older than 40 (Furman).
Incidence of cervical spine disc herniation with radiculopathy is 5.5 per 100,000 population, as opposed to self-reported neck pain, which occurs in 21,300 per 100,000 population (Hogg-Johnson).
Thoracic disc herniation is rare, occurring in 0.1 per 100,000 population and comprising 0.75% of all disc injuries (Hannani).
Lumbar disc herniation occurs 15 times more frequently than disc herniation in the cervical spine ("Herniated Nucleus Pulposus").
Lifetime prevalence of lumbar disc disease resulting in sciatica is 5% of males and 2.5% in females (Sahrakar). Individuals between 30 and 55 years of age are most at risk for acute lumbar disc herniation, with 90% of injuries occurring at the L4-L5 and L5-S1 levels (Palacio).
Source: Medical Disability Advisor