Herniated nucleus pulposus

[Justin Bieber]

Herniated nucleus pulposus is prolapse of an intervertebral disk through a tear in the surrounding annulus fibrosus. The tear causes pain because of the nerves in the disk, and when the disk impinges on an adjacent nerve root, a segmental radiculopathy with paresthesias and weakness in the distribution of the affected root results. Diagnosis is usually by MRI or CT. Treatment of mild cases is with analgesics, activity modification, and physical therapy. Bed rest is rarely indicated. Patients with progressive or severe neurologic deficits, intractable pain, conservative treatment failure, or cauda equina syndrome with associated sphincter dysfunction may require immediate or later elective surgery (eg, diskectomy, laminectomy).
Spinal vertebrae are separated by fibrocartilaginous disks consisting of an outer annulus fibrosus and an inner nucleus pulposus. When degenerative changes (with or without trauma) result in protrusion or rupture of the nucleus through the annulus fibrosus in the lumbosacral or cervical area, the nucleus is displaced posterolaterally or posteriorly into the extradural space.
Radiculopathy occurs when the herniated nucleus compresses or irritates the nerve root. Posterior protrusion may compress the cord in the cervical, thoracic, or upper lumbar spine or the cauda equina, especially in a congenitally narrow spinal canal (spinal stenosis). In the lumbar area, gt; 80% of disk ruptures affect L5 or S1 nerve roots; in the cervical area, C6 and C7 are most commonly affected.
Herniated disks are common.