ESTES PARK, COLO. – When a patient presents with low back pain, the single most important question to ask is this: “Are you having nocturnal pain or pain that’s unrelieved by rest?
“I really, really like this question. Most low back pain is nonspecific. Less than 5% of patients (with low back pain) have serious systemic pathology, but that’s the 5% we can’t afford to miss initially. This question gets at a key red flag for systemic disease,” Dr. Robert W. Janson explained at a conference on internal medicine sponsored by the University of Colorado.
“If you have mechanical low back pain, when you rest you feel good, just like with osteoarthritis. So if you’re writhing all night or unable to find a comfortable position, then you’re usually in that 5%. It’s inflammatory, metastatic, infectious, a fracture, or acute nerve compression,” said Dr. Janson, chief of rheumatology at the Denver VA Medical Center.
Other red flags for systemic disease include unexplained weight loss, fevers, or sweats; age over 50 years; low back pain present for longer than 6 weeks; or pain that’s unresponsive to treatment. A history of cancer, osteoporosis, corticosteroid therapy, abdominal aortic aneurysm, bowel or bladder symptoms, intravenous drug abuse, skin or urinary tract infection, morning stiffness lasting more than an hour, or sensory or motor loss are additional red flags.
Dr. Janson noted that these are essentially the same criteria the American College of Radiology uses in its 2011 recommendations on the appropriateness of obtaining a lumbar MRI.
Differentiating between mechanical low pain and the far less common inflammatory back pain, or axial spondyloarthropathy, is crucial because the prognosis and treatment are so different.
Inflammatory back pain is typically insidious in onset, relieved by exercise, frequently associated with nocturnal pain, entails more than 60 minutes of morning stiffness, and begins prior to age 40. In contrast, mechanical back pain can begin at any age, is acute in onset, exacerbated by exercise, doesn’t involve nighttime pain, and typically features less than 30 minutes of morning stiffness.
Most mechanical low back pain is self-limited and resolves within 4 weeks. It is characterized by abnormal back flexion, whereas patients with inflammatory back pain lose back mobility in all planes. They also frequently have sacroiliac joint tenderness and reduced chest expansion; patients with mechanical low back pain do not. Neurologic deficits are unusual in patients with spondyloarthropathies, since they are typically young individuals without disc disease.
Dr. Janson reported having no financial conflicts regarding his presentation.