Acute Low Back Pain Case File

Acute Low Back Pain Case File

Eugene C. Toy MD, Donald Briscoe, MD, FA  AFP, Bruce Britton, MD, Joel J. Heidelbaugh, MD, FA  AFP, FACG

Case 53

A previously healthy 48-year-old accountant presents to his primary care office with severe low back pain that began the previous day after he helped his daughter move into her college dorm. He denies any trauma or previous back injury. He describes the pain as generally "achy;' and sometimes characterized as being "sharp"when he moves suddenly. The pain is located in his lower back and radiates down the back of both legs to the middle of his posterior thighs. He has been continent

of both bowel and bladder and denies any weakness in his legs. He denies fever, chills, weight loss, or malaise. He finds it very difficult to stand for prolonged periods of time because he can't find a comfort position. He states that this is the worst back pain he has ever experienced, and it has not been relieved with acetaminophen or ibuprofen. His past medical history is significant for hypertension; his only medications are metoprolol and a baby aspirin daily. He does not smoke or use illicit drugs, and only drinks alcohol on occasion. On physical examination, he is well-developed, overweight, and in moderate discomfort. On neuromuscular examination, he has moderate tenderness bilaterally in his lumbar paraspinous muscles, and his lumbar flexion and extension are limited by pain. Strength and sensation are within normal limits and equal and symmetrical bilaterally, as are his deep tendon knee and ankle reflexes. Straight leg raise testing is negative bilaterally and gait is within normal limits.

⯈ What is the most likely diagnosis?

⯈ What is the most appropriate workup?

⯈ What is the best treatment plan?

ANSWER TO CASE 53

Acute Low Back Pain

Summary: A previously healthy 48-year-old man presents with acute onset of low back pain after strenuous activity. His neurologic examination is unremarkable and he denies any systemic complaints.

• Most likely diagnosis: Acute low back pain, lumbosacral strain.
• Workup: No formal workup is required unless symptoms persist after conservative treatment for at least 1 month.
• Treatment: Rest, nonsteroidal anti-inflammatory drugs (NSAIDs), and muscle relaxants.

ANALYSIS

Objectives

1. Develop a differential diagnosis for acute low back pain and explore it with the history and physical.
2. Learn the "red flag" symptoms of low back pain and how to investigate them.
3. Learn the effective treatments for musculoskeletal back pain.

Considerations

Acute low back pain is one of the most common reasons for a visit to the doctor in the United States. While approximately 85% of patients who present with isolated low back pain will never be given a specific anatomic reason for the pain, over 90% of patients will fully recover within 2 weeks of symptom onset.

Since the differential diagnosis of low back pain is broad, the role of the clinician is to determine if the pain is caused by a systemic disease, if it is associated with neurologic compromise, and to consider psychosocial factors that may lead to chronic back pain and complicate the recovery or efficacy of treatment.

This patient's history includes pertinent positive findings of being overweight and a recent history of repetitive lifting and twisting that are associated with lumbosacral strain. His signs, symptoms, and physical examination are all consistent with a localized musculoskeletal condition. His age and lack of systemic symptoms are pertinent negative findings. He is not depressed and denies a history of substance abuse. This clinical scenario is best managed by symptomatic therapies for 4 to 6 weeks, without imaging, with close follow-up in 1 month if symptoms do not resolve. Education in proper lifting techniques and exercise therapy to improve core and back strength and flexibility may help to prevent future strain and injury.

Approach To:

Low Back Pain

DEFINITIONS

HERNIATED DISC: Rupture of the fibrocartilage between the vertebrae leading to leakage of the nucleus pulposus that may impinge on the nerve roots causing pain.

SCIATICA: A sharp or burning pain that radiates along the path of the sciatic nerve (L4-S2) usually caused by a herniated disk of the lumbar region of the spine, which typically radiates to the buttocks and to the posterior thigh.

CLINICAL APPROACH

Acute low back pain should be evaluated in a systematic manner to avoid missing important"red flag" symptoms (Table 53-1) and unnecessary imaging, treatments, or referrals. The first step is to generate a differential diagnosis (Table 53-2) and to understand the common signs and symptoms of its components.

History, Physical, and Evaluation

The history in the patient presenting with acute low back pain must triage minor back conditions from those requiring urgent evaluation via a methodologic and consistently sound approach. Patients presenting with cauda equinasyndrome have increasing neurologic deficits and leg weakness, bowel and/or urinary incontinence, anesthesia or paresthesia in a saddle distribution, and bilateral sciatica. Physical findings include pain elicited by straight leg raise test, reduction in anal sphincter tone, and decreased bilateral ankle reflexes. These patients require immediate evaluation with lumbosacral magnetic resonance imaging (MRI), corticosteroids to

Abbreviation: PIO, pelvic inflammatory disease.

Data from Kinkade S. Evaluation and treatment of acute low back pain. Am Fam Physician. 2008;75: 1181-1188, 1190-1192;

Deyo RA, Weinstein JN. Low back pain. N EnglJ Med. 2001;344(5):363-370.

decrease pain and inflammation, and commonly immediate surgical decompression of the entrapped cauda equina to prevent further neurologic deterioration.

Fevers, point tenderness directly over the vertebrae, recent infections, and a history of intravenous drug use can point toward an infectious process like osteomyelitis, septic discitis, paraspinous abscess, or epidural abscess. These infections should be promptly considered and evaluated by complete blood count (CBC), erythrocyte sedimentation rate (ESR), cultures from blood and abscess contents, cerebral

spinal fluid (CSF), and MRI and require long courses of intravenous antibiotics and sometimes surgical drainage. An underlying cancer is much more likely if the patient has a history of cancer with a likelihood of metastasis to bone ( eg, prostate, hematologic, breast, lung), unexplained weight loss, worsening pain at night, failure to improve after 1 month of conservative therapy, or an age greater than 50. To further evaluate patients with these risk factors, a CBC, ESR, and plain radiographs of the lumbar sacral spine should be obtained initially. Abnormalities in these tests should be further evaluated by MRI and/or a bone scan.

The history should also help to differentiate less urgent but important causes of low back pain. Sciatica is the classic sign of a herniated disc. It is typically characterized by a sharp or burning back pain that radiates down the back and side of the leg and distal to the knee. It improves on lying down and increases with Valsalva maneuver, sneezing, or coughing. Additional symptoms of radiculopathy may include anesthesia, dysesthesia, hyperesthesia, and paresthesia that are confined to a specific lumbosacral dermatome. Sciatica can be examined by performing both a straight leg raise test ( 91% sensitive, 26% specific) and a contralateral leg raise test (29% sensitive, 88% specific), along with sensory, strength, and reflex testing of the lower extremities (L4-knee strength and reflex; LS-great toe and foot dorsiflexion; and Sl-plantar flexion and ankle reflexes). Greater than 90% of lumbar disc compression of nerve roots occurs at L4-L5 and LS-Sl. MRI is not recommended for patients with sciatica unless the symptoms last for more than 1 month or if the patient is not a candidate for an epidural corticosteroid injection or surgical intervention.

Conservative treatment for sciatica involves anti-inflammatories including NSAIDs or acetaminophen, muscle relaxants including cyclobenzaprine, possibly short-course oral corticosteroids, and activity modifications. Given the lack of proven efficacy and potential adverse drug reactions, opioid use is generally reserved for patients who have severe pain and who have exhausted nonnarcotic treatment options. Physical therapy may be appropriate for individuals with persistent moderate symptoms of 3 weeks or more, since the majority of the patients are likely to experience spontaneous improvement in the first 2 weeks. Surgical options may be considered in those who suffer from disabling radicular pain of 6 weeks or more or with progressive neuropathic deficits.

Spinal stenosis is a congenital or acquired condition of spinal canal narrowing with or without concomitant facet hypertrophy that exerts pressure on the spinal cord and nerve roots. Degenerative arthritis and spondylolisthesis are the most common acquired causes of lumbar spinal stenosis. Congenital causes include dwarfism, spina bifida, and myelomeningocele. It presents as lower back and leg pain, leg weakness, and pseudoclaudication that occurs after walking various distances, while the vascularity of the legs remains uncompromised. The majority of patients with spinal stenosis are symptomatic only when engaged in activities. Pain is often relieved by sitting, performing lumbar flexion (bending over), squatting, or a laying down. It is more common in patients over 60 and its rules of evaluation are the same as for a herniated disc. Spinal stenosis is initially treated with NSAIDs and muscle relaxants, physical therapy, and epidural corticosteroid injections. Surgical therapy is reserved for patients who have failed conservative treatment or those with progressive neurologic deficits.

Vertebral compression fractures are more common in older people and those with osteoporosis or chronic corticosteroid use. These commonly occur after low impact trauma or with no trauma history at all. Patients typically present with acute onset of back pain after certain sudden movements such as lifting, bending, or coughing. The pain often follows the distribution of the contiguous nerve and radiates bilaterally into the anterior abdomen or pelvis, also known as the "girdle of pain:' The fractures are generally well localized to the thoracolumbar segment (T12-L2) of the spine. Vertebral compression fractures are best initially evaluated by plain film radiographs of the thoracolumbar spine. They can be treated medically with pain control, physical therapy, and with calcitonin and bisphosphonates, as well as treatment of the underlying osteoporosis. Spinal bracing and surgical management with balloon kyphoplasty can be considered and may have better outcomes than medical management in those with severe pain.

Psychosocial factors and emotional distress should also be evaluated in the patient with low back pain. Depression, fear avoidance (fear that activity will cause permanent damage), job dissatisfaction, current involvement in litigation, reliance on passive treatments, or somatization are predictors of slow recovery and increase the risk for developing chronic low back pain. Acknowledgement and management that includes treatment of such factors as applicable may be effective adjuvant therapy.

The vast majority of patients seeking medical evaluation with back pain will be diagnosed with lumbosacral strain. The exact anatomic cause of the pain is often unknown, but it is often hypothesized that there may be an incomplete tear in the annulus fibrosus that may leak fluids creating local inflammation, or it may bulge posteriorly and irritate certain lumbar roots. Irritation of the surrounding muscles, tendons, ligaments, or the joint capsule may be concomitantly involved in this painful process.

Treatment of Acute Mechanical Back Pain

The treatment of acute mechanical back pain (< 4 weeks) centers on the use of NSAIDs, acetaminophen, muscle relaxants, heat, and early mobility. No significant benefit has been observed with the use of opioids, systemic corticosteroids, or bed rest. Bed rest for any length of time has not been shown to improve pain and may lengthen the duration of pain and prolong recovery. For those with moderate to severe pain, combination therapy of a muscle relaxant and an NSAID may be more effective than monotherapy. Due to their sedative effects, muscle relaxants are typically recommended for nighttime dosing. In general, patients should be encouraged to resume normal daily activities as tolerated with reasonable restrictions on bending and lifting until the pain resolves. Specific exercises have not been proven to be beneficial in speeding recovery. Massage therapy and spinal manipulation may be of some benefit for acute pain; physical therapy has some benefit for short-term pain relief, but most studies do not show long-term benefit. Although acupuncture and yoga may be reasonable options for chronic back pain, their effectiveness in acute back pain remains unproven. Spinal traction has not been shown to be helpful for chronic back pain with or without sciatica. For prevention, exercise has been proven to help prevent first episodes of back pain and recurrences in certain subgroups of workers. Lumbar support braces have not been shown to prevent low back pain.

CASE CORRELATION

• See also Case 3 (Joint Pain).

COMPREHENSION QUESTIONS

53.1 A 45-year-old man with no significant past medical history presents with severe back pain after lifting heavy boxes at work 2 days ago. Other than his back pain, his review of symptoms is negative. The pain radiates from his lower back down his right posterior thigh to his great toe when you perform both a straight leg raise and the contralateral leg raise tests. His strength, sensation, and reflexes are intact and symmetrical. Which of the following imaging studies should be done first in the evaluation of this patient?

A. Plain radiographs

B. MRI

C. Computed tomography (CT) scan

D. No imaging indicated

E. Bone scan

53.2 A 58-year-old white woman presents complaining of low back pain for exactly 1 month after a fall. She has no history of fever, unexplained weight loss, diabetes, or cancer. Her past medical history is significant for mild persistent asthma and nicotine dependence. She had a hysterectomy for uterine fibroids at age 40. Which of the following characteristics should prompt further evaluation of her pain?

A. History of corticosteroid use

B. Caucasian ethnicity

C. Time course of back pain

D. History of cocaine use

E. Premenopausal age

53.3 A 67-year-old man with coronary artery disease, dyslipidemia, and eczema comes to you complaining of lower back pain and left leg pain. The pain is worse when he stands for long periods of time, but improves when he bends forward to push his shopping cart around the grocery store. He indicates that his feet" burn" and "ache" after walking different distances every day. His lower extremity neuromuscular examination is unremarkable. Which of the following is the most appropriate treatment for this patient?

A. Emergent spinal cord decompression

B. Epidural corticosteroid injection

C. Kyphoplasty

D. Bed rest for 4 days

E. Tramadol

ANSWERS

53.1 D. The patient has signs and symptoms of a herniated disc. There is no evidence that imaging within the first month has any morbidity benefit.

53.2 A. The patient's history is suspicious for a vertebral compression fracture that could be secondary to osteoporosis. Osteoporosis commonly develops in postmenopausal women, and can occur in patients who have received corticosteroid therapy. The time course of her pain is 4 weeks; 6 weeks and greater is a "red flag" symptom for further evaluation with radiographic imaging. While osteoporosis is more common in Caucasian women, it is not considered a" red flag:' Postmenopausal women are at greater risk for osteoporosis rather than premenopausal women. Smoking and alcohol dependence are risk factors for osteoporosis; there is no evidence that cocaine use contributes to the development of osteoporosis.

53.3 B. The patient's history is classic for spinal stenosis. Often patients find relief by sitting or stooping. NSAIDs, physical therapy, and epidural corticosteroid injections are used to relieve pain. Surgical decompression is used in cauda equina syndrome, and kyphoplasty is useful in vertebral fractures. Bed rest is not used in the conservative treatment of back pain for any cause and has been shown to increase the duration of pain.

CLINICAL PEARLS

⯈ "Red flag" symptoms in low back pain should prompt an immediate diagnostic workup.

⯈ Cauda equina syndrome is a surgical emergency that should be evaluated immediately by MRI.

⯈ A herniated disc can be treated conservatively for 4 weeks before radiographic imaging has any proven benefit.

⯈ Lumbosacral strain is common, generally resolves within a few weeks, and is treated with NSAIDs and muscle relaxants. Bed rest likely provides no significant benefit and may prolong pain and slow recovery.

REFERENCES

Balague F, Mannion AF, Pellise F, Cedraschi C. Non-specific low back pain. Lancet. 2012:379(9814): 482-491. 

Casazza BA. Diagnosis and treatment of acute low back pain. Am Fam Physician. 2012:85(4):343-350. 

Chou R, Huffman LH. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med. 2007;147: 478-491. 

Delitto A, George SZ, Van Dillen LR, et al. Low back pain: clinical practice guidelines linked to the International Classification of Functioning, Disability, and Health from the Orthopaedic Section of the American Physical Therapy Association.] Orthop Sports Phys Ther. 2012;42( 4):Al-A57. 

Kamper SJ, Apeldoorn AT, Chiarotto A, et al. Multidisciplinary biopsychosocial rehabilitation for chronic low back pain: Cochrane systematic review and meta-analysis. BM]. 2015;350h444. 

Klineberg E, Mazanec D, Orr D, Demicco R, Bell G, McLain R. Masquerade: medical causes of back pain. Cleve Clin ] Med. 2007;74(12):905. 

Last AR, Hulbert K. Chronic low back pain: evaluation and management. Am Fam Physician. 2009;79(12):1067-1074. 

Lemeunier N, Leboeuf-Yde C, Gagey 0. The natural course oflow back pain: a systematic critical literature review. Chiropr Man Therap. 2012;20(1):33.

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