eMedicine Specialties > Sports Medicine > Spine

Lumbosacral Radiculopathy

Gerard A Malanga, MD, Associate Professor, Department of Physical Medicine and Rehabilitation, New Jersey Medical School; Director of Pain Management, University of Medicine and Dentistry at New Jersey, Overlook Hospital; Director of Sports Medicine, Mountainside Hospital
Charles J Buttaci, DO, PT, Staff Physician, Department of Physical Medicine and Rehabilitation, Kessler Institute for Rehabilitation, University of Medicine and Dentistry of New Jersey; Mariam Rubbani, MD, Consulting Staff, Department of Physical Medicine and Rehabilitation, Union County Orthopedic Group
Contributor Information and Disclosures

Updated: Dec 5, 2007

Introduction

Background

 Some of the major causes of acute and chronic low back pain (LBP) are associated with radiculopathy. However, radiculopathy is not a cause of back pain; rather, nerve root impingement, disc herniation, facet arthropathy, and other conditions are causes of back pain.^{1, 2, 3}

(See also the eMedicine articles Back Pain, Mechanical [in the Emergency Medicine section], Lumbar Disc Disease [in the Neurosurgery section], Herniated Nucleus Pulposus [in the Orthopedic Surgery section], Degenerative Lumbar Disc Disease in the Mature Athlete [in the Sports Medicine section], and Lumbar Degenerative Disk Disease, Lumbar Spondylolysis and Spondylolisthesis, and Lumbar Facet Arthropathy [in the Physical Medicine and Rehabilitation section], as well as color="Guidelines Issued for Management of Low Back Pain, Strategies for Evaluation and Treatment of AcuteLow Back Pain, color="Lumbar Spine Injuries in Athletes, Treatment of Lumbar Spinal Stenosis With a  Total  Posterior Arthroplasty Prosthesis: Implant Description, Surgical Technique, and a Prospective Report on 29 Patients on Medscape.)

Lumbosacral radiculopathy, like other forms of radiculopathy, results from nerve root impingement and/or inflammation that has progressed enough to cause neurologic symptoms in the areas that are supplied by the affected nerve root(s).

For excellent patient education resources, visit eMedicine's Osteoporosis and Bone Health Center, Back, Ribs, Neck, and Head Center, and Back, Neck, and Head Injury Center. Also, see eMedicine's patient education articles Back Pain and Slipped Disk.

Frequency

United States

Functional Anatomy

The anatomy of the lumbar epidural space is the key to understanding the mechanism of radiculopathic pain. The sinuvertebral nerves innervate structures in the lumbar epidural space; these nerves originate distal to the dorsal root ganglion, then run back through the intervertebral foramen to supply the arteries, venous plexi, and lymphatics. At the inner aspect of the intervertebral foramen, the sinuvertebral nerves divide into ascending and descending branches that freely communicate with corresponding branches from the segment above, from the segment below, and from the opposite side.

The sinuvertebral nerve supplies the posterior longitudinal ligament, superficial annulus fibrosus, epidural blood vessels, anterior dura mater, dural sleeve, and posterior vertebral periosteum. The 2 structures capable of transmitting neuronal impulses that result in the experience of pain are the sinuvertebral nerve and the nerve root. The posterior rami of the spinal nerves supply the apophyseal joints above and below the nerve and the paraspinous muscles at multiple levels.

Herniation of the intervertebral disc can cause impingement of the above neuronal structures, thus causing pain. The presence of disc material in the epidural space is thought to initially result in direct toxic injury to the nerve root by chemical mediation and then exacerbation of the ensuing intraneural and extraneural swelling, which results in venous congestion and conduction block. Notably, the size of the disc herniation has not been found to be related to the severity of the patient's pain.

Pain is also believed to be mediated by inflammatory mechanisms involving substances such as phospholipase A2, nitric oxide, and prostaglandin E. These mediators are all found in the nucleus pulposus itself. Phospholipase A2 has been found in high concentrations in herniated lumbar discs; this substance acts on cell membranes to release arachidonic acid, a precursor to other prostaglandins and leukotrienes that further advance the inflammatory cascade. Additionally, leukotriene B4 and the substance thromboxane B2 have been found to have direct nociceptive stimulatory roles.

From a biomechanical standpoint, the lumbar intervertebral discs are highly susceptible to herniation because they are exposed to tremendous forces, principally by the magnification of the forces that result from the lever effect of the human arm in lifting; the forces generated by the upper trunk mechanics with rotation, flexion/extension, and side-bending on the discs below; and by the vertical forces associated with the upright position. Because each intervertebral disc is a fluid system, hydraulic pressure is generated whenever a load is placed on the axial skeleton. The hydraulic pressure mechanisms then multiply the force on the annulus fibrosus of the intervertebral disc to make it 3-5 times that which is exerted on the axial skeleton.

Sport-Specific Biomechanics

Dancers are prone to both acute and chronic back problems, which develop secondary to the combination of 2 factors that are required in most dance routines: extreme physical flexibility and exposure of the spine to the extremes of its range of motion.¹ Additionally, female dancers are predisposed to disc herniation secondary to the positioning that is required in certain movements, such as the pas de deux (in which excess lumbar lordosis is present), as well as the large jumps that these dancers often perform.

Golfers are also very susceptible to disc disease and radiculopathy because of the repetitive torsional motion that is used in the sport.⁵ The golf swing can produce up to an estimated 7500 N of compressive force across L3-L4. Competitive weight lifters and football linemen have been noted to experience even larger compressive loads.

Clinical

History

• The onset of symptoms in patients with lumbosacral radiculopathy is often sudden and includes LBP. Some patients state the preexisting back pain disappears when the leg pain begins.
• Sitting, coughing, or sneezing may exacerbate the pain, which travels from the buttock down to the posterior or posterolateral leg to the ankle or foot.
• Radiculopathy in roots L1-L3 refers pain to the anterior aspect of the thigh and typically does not radiate below the knee, but these levels are affected in only 5% of all disc herniations.
• When obtaining a patient's history, be alert for any red flags (ie, indicators of medical conditions that usually do not resolve on their own without management). Such red flags may imply a more complicated condition that requires further workup (eg, tumor, infection).⁶ The presence of fever, weight loss, or chills requires a thorough evaluation. Patient age is also a factor when looking for other possible causes of the patient's symptoms. Individuals younger than 20 years and those older than 50 years are at increased risk for more malignant causes of pain (eg, tumor, infection).

Physical

A comprehensive physical examination of a patient with acute LBP should include an in-depth evaluation of the neurologic and musculoskeletal systems.

• The neurologic examination should always include an evaluation of sensation, strength, and reflexes in the lower extremities. This portion of the examination allows the examiner to detect sensory or motor deficits that may be consistent with an associated radiculopathy or cauda equina syndrome. Often, an assessment of the L5 reflex (medial hamstrings) is helpful. (See also the eMedicine articles Cauda Equina and Conus Medullaris Syndromes [in the Neurology section], Cauda Equina Syndrome [in the Emergency Medicine section], and Cauda Equina Syndrome [in the Orthopedic Surgery section], as well as Hip-Spine Syndrome: The Effect of Total Hip Replacement Surgery on Low Back Pain in Severe Osteoarthritis of the Hip and Strategies for Evaluation and Treatment of Acute Low Back Pain on Medscape.)When differentiating between an L3 radiculopathy versus a femoral neuropathy, weakness in the hip adductors in addition to the quadriceps group would indicate an L3 radiculopathy. In an isolated femoral neuropathy, only the quadriceps group would show weakness.
• Provocative maneuvers, such as the straight-leg raising test or the slump test, may provide evidence of increased dural tension, indicating underlying nerve root pathology. Attempts at pain centralization through postural changes (ie, lumbar extension) may suggest a discogenic etiology for pain and may also assist in determining the success of future treatment strategies.

• The musculoskeletal evaluation should include an assessment of the lower extremity joints, as pain referral patterns may be confused with focal peripheral involvement. For example, a patient with anterior thigh and knee pain may actually have a degenerative hip condition rather than an upper lumbar radiculopathy. By assessing lower extremity flexibility, hip rotation, muscular balance, and ligamentous stability, the evaluating physician might be alerted to the patient's predisposition toward an acute LBP episode.
• Combining the findings of the patient's history and physical examination increases the overall predictive value of the clinical evaluation process. Further diagnostic studies are indicated only upon the completion of a thorough history and physical examination and the establishment of a differential diagnosis.

References

• Lumbosacral Disc Injuries
• Thoracic Disc Injuries
• Trochanteric Bursitis

• Bone Health Center
• Back Pain Overview
• Back Pain Causes
• Back Pain Symptoms
• Back Pain Treatment