eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics

Lumbar (Intervertebral) Disk Disorders

Author: Jere F Baldwin, MD, Medical Director, Department of Emergency Medicine, Mercy Hospital Port Huron
Coauthor(s): Jeffrey Horwitz, DO, Director, Assistant Clinical Professor, Department of Emergency Medicine, North Shore University Hospital at Forest Hills
Contributor Information and Disclosures

Updated: Jan 28, 2009

Introduction

Background

Lumbar disk disease is a frequent source of low back pain. Sciatica is defined as neuralgia along the course of the sciatic nerve.

Pathophysiology

The intervertebral disks act as shock absorbers and are found between the bodies of the vertebrae. They have a central area composed of a colloidal gel, called the nucleus pulposus, which is surrounded by a fibrous capsule, the annulus fibrosis. This structure is held together by the anterior longitudinal ligament, which is anterior to the vertebral bodies, and the posterior longitudinal ligament, which is posterior to the vertebral bodies and anterior to the spinal cord. The muscles of the trunk provide additional support.

The most common site of disk herniation is at the L5-S1 interspace in the lumbosacral region. This is believed to be due to the thinning of the posterior longitudinal ligament as it extends caudally.

Nomenclature specific to lumbar disk disease is as follows:

• Disk bulge - Annular fibers intact
• Disk protrusion - Localized bulging with damage of some annular fibers
• Disk extrusion - Extended bulge with loss of annular fibers, but disk remains intact
• Disk sequestration - Fragment of disk broken off from the nucleus pulposus

Frequency

United States

Sciatica has been reported by various authors to occur in 1-10% of the population.

Mortality/Morbidity

Low back pain usually is self-limited and of short duration.

Sex

The male-to-female ratio is approximately 1:1.

Age

The group most commonly affected is adults aged 25-45 years.

Clinical

History

The history may be sufficient to make presumptive diagnosis of a disk disorder, or it may guide the physician's usage of ancillary testing and consultations to further differentiate both the specific type of disk disease and potential other etiologies of the patient's back pain.

• Patients with disk disease usually are not able to give a precise time that the problem began because it usually is preceded by multiple episodes of less severe low back pain.
• Asking the patient the location of the pain is important.
  • Pain that is localized to the lower back and gluteal area often is associated with disk disease.
  • Pain associated with nerve root involvement commonly radiates down the leg, particularly below the level of the knee.
  • Ask the patient about any unusual recent activity, especially if it involved the patient remaining in a flexed or rotated position. Find out if the patient experienced any recent trauma.
  • Pain with flexion, rotation, or prolonged sitting or standing, and sharp (rather than dull) pain are suggestive of disk disease.
  • The onset of pain may begin suddenly¹ or gradually after injury.
  • Typically, the pain is located bilaterally at the posterior belt line.
  • The pain pattern usually is referred rather than radicular.
  • Back motion, which includes sitting, standing, lifting, bending, and twisting, usually aggravates the pain; it often is relieved with rest and a recumbent position.

Physical

Nerve roots exit the spine below the intervertebral disks; thus, herniation of a disk involves the nerve root below it.

• Observe the patient for abnormal gait, which is suggestive of a loss of the normal rhythm. Have ambulatory patients walk on their toes to test the function of S1.
• Observe the patient for abnormal posture, which is suggestive of splinting or guarding from pain.
• Test the patient's ability to dorsiflex the foot while sitting to test the L5 nerve root. Test for sensory loss that corresponds to a dermatomal area.
• Palpation of the lumbar spine and lower back is not helpful in the diagnosis of disk disease, but it should be done to rule out other causes of low back pain.
• A positive straight leg raising test is indicative of nerve root involvement.
  • This test is performed while the patient is lying supine with one leg either straight or flexed at the knee, with the sole of the foot flat on the stretcher. The other leg is kept straight and lifted by the examiner.
  • If pain occurs when the leg is lifted between 30-70 degrees from horizontal and travels down the leg until below the knee, the test is positive.
• Nerve root stretch test results are often negative.
• Patients may exhibit decreased lumbar range of motion (ROM).
• The usual motor, sensory, and reflex examinations (including perianal sensation and anal sphincter tone when appropriate) should be performed.
• A careful abdominal and vascular examination is mandatory in evaluation of these patients.

Causes

• The normal aging process of the musculoskeletal system aggravates acute events.
• Risk factors
  • Age
  • Activity
  • Smoking
  • Obesity
  • Vibration (eg, driving a car)
  • Sedentary lifestyle
  • Psychosocial factors

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