Vol. 15, Issue 6 Oct 2015

Case Management: Low Back Pain and Sciatica in an Adult

Contributing Author: Nathan Prahlow, MD

ACCREDITATION STATEMENT
Indiana University School of Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

DESIGNATION STATEMENT
Indiana University School of Medicine designates this enduring material for a maximum of 1.0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

FACULTY DISCLOSURE STATEMENT
In accordance with the Accreditation Council for Continuing Medical Education (ACCME) Standards for Commercial Support, educational programs sponsored by Indiana University School of Medicine (IUSM) must demonstrate balance, independence, objectivity, and scientific rigor. All faculty, authors, editors, and planning committee members participating in an IUSM-sponsored activity are required to disclose any relevant financial interest or other relationship with the manufacturer(s) of any commercial product(s) and/or provider(s) of commercial services that are discussed in an educational activity.

COMMITTEE AND AUTHOR DISCLOSURE
Statements of Disclosure of Relevant Financial Relationships have been obtained from Nathan Prahlow, MD. Dr. Prahlow has disclosed that he has no relevant financial relationships with any commercial interests.

OBJECTIVES
After reading this article, the reader should be able to:

  • Discuss the usual prognosis for LBP.
  • Identify the major etiologies associated with sciatica.
  • Describe the initial evaluation of LBP.
  • Summarize the various treatment modalities used in the management of LBP and sciatica.
  • Assess the role of exercise during and after an episode of LBP.

Date of original release: October 2015
Date of expiration: October 2016

Note: While it offers CME credits, this activity is not intended to provide extensive training or certification in the field.

Overview and Etiology of Low Back Pain

Low back pain (LBP) is the most common musculoskeletal problem worldwide, experienced by more than eight in 10 adults at some point in their lives.1 In addition to its enormous impact on daily activities, quality of life, and work-related disability, the economic burden of LBP is staggering, exceeding $100 billion per year in direct and indirect costs in the United States alone.2 Yet despite these sobering statistics, the prognosis for acute LBP is generally excellent.

“Eighty to 90 percent of affected individuals improve within the first four to six weeks after an onset of lower back pain,” reports Nathan Prahlow, MD, co-director of the Back & Neck Center at IU Health West Hospital and assistant professor of clinical physical medicine and rehabilitation at IU School of Medicine. “Although the problem tends to recur—30 to 60 percent of individuals will have another episode within the first year—most recurrences follow much the same pattern as the initial event.”3

More than 85 percent of patients seen in the primary care setting have nonspecific LBP that cannot be reliably attributed to a specific disease or spinal pathology.4 Fewer than one percent have a serious systemic etiology (e.g., cauda equina syndrome, metastatic cancer, spinal infection), and under 10 percent have less serious, specific etiologies, such as vertebral compression fracture.5 Nearly all individuals with serious etiologies have risk factors and/or symptoms other than LBP.

An estimated five to 10 percent of patients with LBP also have sciatica6 and experience one-sided pain that radiates through the buttock and down the leg, usually to the foot. According to Dr. Prahlow, radiating leg pain generally results from one of six etiologies (Figure 1):

Lumbar radiculopathy – damage to a spinal nerve root, often caused by degenerative changes in the vertebrae or disc herniation.

Central spinal stenosis – narrowing of the central spinal canal that causes pressure on the nerve roots.

Lateral recess stenosis – narrowing of the central canal exit and subsequent impingement of the nerve roots.

Sacroiliac joint dysfunction – caused by misalignment or abnormal movement of the joint between the sacrum and pelvis.

Facet joint arthropathy – degenerative disease of the spinal joints and cartilage.

Piriformis syndrome – compression or irritation of the sciatic nerve caused by spasm of the piriformis muscle (Figure 2).


Case Study

A 60-year-old man with a chronic “achy back” he attributes to work as a laborer is referred to Indiana University Health following a six-month history of increased LBP resulting from a slip and fall on ice. The pain radiates down his right buttock and leg to the foot, is associated with numbness and tingling, and was not relieved by a short trial of a non-steroidal antiinflammatory drug (NSAID) prescribed by his primary care physician.

Initial Evaluation

The initial clinical evaluation of LBP with or without radiating leg pain includes a focused history and physical examination to identify signs or symptoms indicating the need for immediate imaging and further evaluation (Table 1). These “red flags” include severe or progressive neurologic deficits and the possibility of a serious underlying condition, such as malignancy or infection. For most patients with acute LBP of less than four weeks duration, laboratory tests and imaging are unnecessary. Not only does early imaging for LBP not improve outcomes, but it increases the use of invasive procedures that may be unnecessary. Moreover, abnormal findings on imaging are common and can confound the diagnosis.

“Magnetic resonance imaging (MRI) performed on asymptomatic adults showed that 80 percent have bulging discs, 22 to 67 percent have disc herniations, and 21 percent over age 60 have spinal stenosis,”8-10 Dr. Prahlow points out.

When symptoms of LBP fail to improve after four to six weeks of conservative therapy that incorporates exercise and oral pharmacotherapy (e.g., acetaminophen, NSAIDs, muscle relaxants, opioids, corticosteroids), imaging may be indicated. MRI is preferred to computed tomography because it does not involve exposure to ionizing radiation and has better visualization of soft tissue, vertebral marrow, and the spinal canal.

When symptoms of LBP fail to improve after four to six weeks of conservative therapy that incorporates exercise and oral pharmacotherapy (e.g., acetaminophen, NSAIDs, muscle relaxants, opioids, corticosteroids), imaging may be indicated. MRI is preferred to computed tomography because it does not involve exposure to ionizing radiation and has better visualization of soft tissue, vertebral marrow, and the spinal canal.

Case Study (cont.)

Digital palpation of the patient’s spine and buttocks elicits deep pain over the right piriformis muscle that radiates down the posterior thigh and wraps around the anterior surface of the lower limb to the foot. Neurologic examination shows normal reflexes. Lumbar imaging is ordered to further evaluate the problem. Anteroposterior and lateral X-rays demonstrate multilevel degenerative changes. MRIs show bulging discs at L3-4, a disc herniation at L4-5 (Figure 3), and facet joint arthropathy at multiple levels; the sacroiliac joints appear normal. Electromyography (EMG) is performed and is negative, suggesting that piriformis syndrome (Table 2), rather than an active radiculopathy, is responsible for the radiating leg pain.

Treatment

Pharmacotherapy, Physical Therapy, and Exercise

Conservative treatment for sciatica caused by piriformis syndrome is primarily aimed at pain reduction and begins with an analgesic or anti-inflammatory (NSAID or oral cor ticosteroid), physical therapy to stretch the piriformis muscle and strengthen the abductor and adductor muscles, and home exercises. Patients are urged to remain active and continue daily activities. While a few hours of bed rest may provide some symptomatic relief, prolonged bed rest is associated with increased pain and a slower recovery. Various self-care options and nonpharmacologic interventions may also help to alleviate LBP and sciatic symptoms (Table 3).

Intramuscular Injections

“Some patients with piriformis syndrome continue to experience persistent pain despite six to eight weeks of conservative treatment and may benefit from steroid injections,” Dr. Prahlow says. “Under fluoroscopic guidance, a local anesthetic and corticosteroid are injected directly into the piriformis muscle at the area of maximal buttock tenderness. Treatment may be provided as a single injection or as series of up to three injections at intervals of at least two weeks.”

For patients who are not sufficiently helped by piriformis steroid injections, some evidence suggests that injection of botulinum toxin may relieve pain by relaxing the spasming muscle and reducing pressure on the sciatic nerve.11 This treatment strategy remains investigational, though, and Dr. Prahlow cautions that long-term studies are needed to determine its ultimate role, if any, in the management of piriformis syndrome.

Case Study (cont.)

The patient’s leg symptoms resolve with an oral corticosteroid, physical therapy, home exercise, and two piriformis muscle steroid injections. However, he has ongoing midline back pain, indicating that facet joint arthropathy may be contributing to LBP. A single facet joint steroid injection provides near-complete relief.

Radiofrequency Nerve Ablation

When facet joint arthropathy is refractory to conservative treatment or steroid injections, radiofrequency nerve ablation may be considered. This technique involves placing a catheter or electrode near or in the target nerve (with position confirmed by fluoroscopy) and ablating it through the application of radiofrequency current. Before the procedure is done, a medial or lateral branch nerve block is performed to demonstrate that pain is being transmitted via a particular nerve(s).

Preliminary studies suggest that radiofrequency nerve ablation is somewhat more effective for relieving cervical versus lumbar pain, and that pain may return if the nerve regenerates (typically after nine to 14 months). A randomized, sham-controlled, double-blind study enrolling 200 patients is currently underway in the United States to evaluate radiofrequency nerve ablation in selected patients with chronic LBP that is not responsive to conservative treatment.

Surgery

For nonradicular LBP with usual degenerative changes, spinal fusion has not been shown superior to intensive rehabilitation.12 Surgery for radiculopathy associated with a herniated lumbar disc or symptomatic spinal stenosis is associated with short-term advantages, as compared with nonsurgical therapy, but some trials have found a diminution of these benefits over time.12

Exercise After Recovery from LBP

“Once an episode of low back pain resolves, it is essential that exercise be continued to maintain improvements and prevent recurrence,” concludes Dr. Prahlow. “In addition to back-specific exercises prescribed by a physical therapist, patients should focus on: 1) increasing core strength (i.e., the abdominal, paraspinal, gluteal, diaphragmatic, pelvic floor, and hip girdle musculature) to facilitate lumbar stability and 2) improving hamstring flexibility. Strengthening and flexibility exercises should be combined with aerobic exercise of the patient’s choosing, such as walking, swimming, or using an elliptical machine.”

“Once an episode of low back pain resolves, it is essential that exercise be continued to maintain improvements and prevent recurrence,” concludes Dr. Prahlow.

Nathan Prahlow, MD

Co-director, Back & Neck Center at IU Health West Hospital
Assistant Professor of Clinical Physical Medicine & Rehabilitation IU School of Medicine Director, IU School of Medicine Physical Medicine & Rehabilitation Residency Education Program
nprahlow@iuhealth.org

Dr. Prahlow received his medical degree from and completed his specialty training in physical medicine and rehabilitation at IU School of Medicine. His practice and research interests center on musculoskeletal medicine (primarily in a worker’s compensation setting) and electromyography.

Dr. Prahlow is the author and/or editor of several textbooks focused on spine and musculoskeletal disorders and their diagnosis and sports medicine and rehabilitation. He is the director of IU School of Medicine physical medicine and rehabilitation residency program.

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