Herniation of Intervertebral Disk

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EPSTEIN, J.A.

Essentials of Diagnosis

Lumbosacral Disk

Back pain aggravated by motion, and pain radiating down the back of the leg and aggravated by coughing or straining.
Sciatic nerve painful to pressure and stretch (straight-leg raising).
CSF protein may be elevated; myelograms reveal characteristic defect.
Cervical Disk
Paroxysmal pains and paresthesias from back of neck radiating into the arms and fingers, usually in distribution of C6, C7, or C8; accentuated by coughing, sneezing, straining.
Restricted mobility of neck; cervical muscle spasm.
Paresthesias and pains in fingers, diminished biceps or triceps jerk, weakness or atrophy of forearm and hand muscles.
Narrowing of vertebral interspace on x-ray; characteristic filling defect or deformity on myelogram.

General Considerations

In most cases rupture or herniation of an intervertebral disk is caused by trauma. Sudden straining with the back in an "odd" position and lifting in the trunk-flexed posture are commonly recognized precipitating causes. The defect may occur immediately after an injury or following an interval of months to years.

The lumbosacral intervertebral disks (LS-S1 or L4-LS) are most commonly affected, producing the clinical picture of sciatica. Herniation occasionally occurs in the cervical region (characterized by cervical radicular complaints); rarely in the thoracic region.

Clinical Findings

A. Symptoms and Signs: These usually depend upon the location and size of the herniated or extruded disk material. Compression of a nerve root by a disk may be confined to a single nerve root; however, several roots may be compressed (eg, cauda equina by disk at L5-S1). Larger cervical and thoracic lesions may even compress the spinal cord and produce symptoms commonly associated with tumors.

1. Lumbosacral disk- In the great majority (over 90 per cent), rupture of the disk occurs at the level of the 4th or 5th lumbar interspace. This is characterized by straightening of the normal lumbar curve, scoliosis toward the side opposite the sciatic pain, limitation of motion of the lumbar spine, impaired straight leg rais-ing on the painful side, tenderness to palpation in the sciatic notch and along the course of the sciatic nerve, mild weakness of the foot or great toe extensors, impaired perception of pain and touch over the dorsum of the foot and leg (in LS or SI distribution), decreased or absent ankle jerk, and radiation of pain along the course of the sciatic nerve to the calf or ankle on coughing, sneezing, or straining.

2. Cervical disk herniation (5-10 per cent of herniated disks)- The cervical disks most commonly involved are between CS-C6 and C6-C7. Paresthesias and pain occur in the upper extremities (hands, forearms, and arms) in the affected cervical root distribution (C6 or C7). Slight weakness and atrophy of the biceps or triceps may be present, with diminution of biceps or triceps jerk. The mobility of the neck is restricted with accentuation of radicular and neck pains by neck motion, coughing, sneezing, or straining. Long tract signs (extensor plantar response, sensory or motor impairment of lower levels, etc) occasionally occur, indicating compression of the spinal cord by the disk.

B. Laboratory Findings: CSF protein may be elevated, and complete or partial CSF block is occasionally demonstrated.

C. X-Ray Findings: Spine x-rays may show loss of normal curvature, scoliosis, and narrowing of the intervertebral disk. A characteristic roentgenologic defect in the subarachnoid space is usually produced by a herniated disk and is readily demonstrable by myelography. Electromyography (EMG) may be of value in localizing the site of a ruptured disk if characteristic denervation potentials can be demonstrated in muscles of a particular root distribution.

Differential Diagnosis

In tumors of the spinal cord the course is progressive, CSF protein is elevated, partial or complete spinal subarachnoid block is present, and the myelographic pattern is distinctive.

In arthritis neurologic findings are usually minimal or absent, and the myelogram is usually negative. Spinal column anomalies show characteristic x-ray findings, CSF findings are negative, and mye-lographic changes are dissimilar or absent.

Treatment

A. General Measures:

1. Lumbosacral disk- In the acute phase, bed rest, heat applied locally to the back, salicylate analgesics, and the use of a bed board under the mattress are indicated. Traction to the lower extremities is frequently beneficial. The avoidance of severe physical effort and strain is essential to minimize recurrence of symptoms after the initial episode.

Low back belts, braces, or supports may be beneficial. It is important to instruct the patient in the proper methods of bend-ing, lifting (with knees flexed), and carrying (with the object held close to the body).

2. Cervical disk- In acute exacerbations of herniated cervical disks, bed rest with cervical halter traction is indicated. In subacute or mild episodes, intermittent cervical halter traction with various devices may be employed on an outpatient basis or at home. The use of a light collar may be helpful. Local application of heat, diathermy, and similar measures may be of temporary value.

B. Surgical Measures: If the response to conservative measures is poor or recurrences are disabling, diskectomy is indicated.

Prognosis

Conservative management with or without traction may bring about improvement to the point of "practical" recovery. Relief of pain usually follows removal of the damaged disk. Reversal of motor dysfunction, muscle atrophy, and skin sensory changes may occur.

The author is co-author of the book ‘Industrial Medicine’.

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