A herniated nucleus pulposus is the protrusion of the hard, cartilaginous center (nucleus) of an intervertebral disk through the outer fibrous tissue (annulus fibrosa) (see Figures 5 and 6 below). Many small HNPs will produce acute symptoms that improve with time. Injection of corticosteroid drugs in the area of the HNP can also help relieve inflammation and pain. Some claimants have a large HNP that presses on a spinal nerve root, and must have part of the HNP removed (discectomy, diskectomy).

figure 5

figure 6

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