Herniated nucleus pulposus (s... Health Article

Definition

A herniated nucleus pulposus is a slipped disk along the spinal cord. The condition occurs when all or part of the soft center of a spinal disk is forced through a weakened part of the disk.

Alternative Names

Lumbar radiculopathy; Cervical radiculopathy; Herniated intervertebral disk; Prolapsed intervertebral disk; Slipped disk; Ruptured disk

Causes, incidence, and risk factors

The bones (vertebrae) of the spinal column run down the back, connecting the skull to the pelvis. These bones protect nerves that come out of the brain and travel down the back and to the entire body. The spinal vertebrae are separated by disks filled with a soft, gelatinous substance, which provide cushioning to the spinal column. These disks may herniate (move out of place) or rupture from trauma or strain.

The spinal column is divided into several segments -- the cervical spine (the neck), the thoracic spine (the part of the back behind the chest), the lumbar spine (lower back), and sacral spine (the part connected to the pelvis that does not move).

Radiculopathy refers to any disease affecting the spinal nerve roots. A herniated disk is one cause of radiculopathy (sciatica).

Most herniation takes place in the lower back (lumbar area) of the spine. Lumbar disk herniation occurs 15 times more often than cervical (neck) disk herniation, and it is one of the most common causes of lower back pain. The cervical disks are affected 8% of the time and the upper-to-mid-back (thoracic) disks only 1 - 2% of the time.

Nerve roots (large nerves that branch out from the spinal cord) may become compressed resulting in neurological symptoms, such as sensory or motor changes.

Disk herniation occurs more frequently in middle aged and older men, especially those involved in strenuous physical activity. Other risk factors include any congenital conditions that affect the size of the lumbar spinal canal.

Symptoms

SYMPTOMS OF HERNIATED LUMBAR DISK

• Severe low back pain
• Pain radiating to the buttocks, legs, and feet
• Pain made worse with coughing, straining, or laughing
• Tingling or numbness in legs or feet
• Muscle weakness or atrophy in later stages
• Muscle spasm

SYMPTOMS OF HERNIATED CERVICAL DISK

• Neck pain, especially in the back and sides
• Deep pain near or over the shoulder blades on the affected side
• Pain radiating to the shoulder, upper arm, forearm, and rarely the hand, fingers or chest
• Pain made worse with coughing, straining, or laughing
• Increased pain when bending the neck or turning head to the side
• Spasm of the neck muscles
• Arm muscle weakness

Signs and tests

A physical examination and history of pain may be all that is needed to diagnose a herniated disk. A neurological examination will evaluate muscle reflexes, sensation, and muscle strength. Often, examination of the spine will reveal a decrease in the spinal curvature in the affected area.

Leg pain that occurs when you sit down on an exam table and lift your leg straight up usually suggests a herniated lumbar disk.

A "foraminal compression test of Spurling" is done to diagnose cervical radiculopathy. For this test, you will bend your head forward and to the sides while the health care provider provides slight downward pressure to the top of the head. Increased pain or numbness during this test is usually indicative of cervical radiculopathy.

DIAGNOSTIC TESTS

• Spine x-ray may be performed to rule out other causes of back or neck pain. However, it is not possible to diagnosis herniated disk by spinal x-ray alone.
• Spine MRI or spine CT will show spinal canal compression by the herniated disk.
• Myelogram may be performed to define the size and location of disk herniation.
• EMG may be performed to determine the exact nerve root(s) that is (are) involved.
• Nerve conduction velocity test may also be performed.