CLINICAL PRINTABLE
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A one-page Low Back Pain clinical reference is on the way.
1 · Recognition / Alarm Features
- Acute low back pain: <4 weeks. Subacute: 4–12 weeks. Chronic: >12 weeks. Most acute nonspecific LBP resolves within 4–6 weeks regardless of treatment. Recurrence is common (40–60% within 1 year).
- Red flags requiring urgent imaging (MRI preferred): cauda equina syndrome (saddle anesthesia, bowel/bladder dysfunction, bilateral leg weakness — surgical emergency), new neurologic deficit, suspected spinal infection (fever, IV drug use, recent spinal procedure, immunocompromised), suspected malignancy (age >50, history of cancer, unexplained weight loss, pain at rest/night), or major trauma.
- Cauda equina syndrome: saddle anesthesia (perineal numbness), urinary retention or incontinence, fecal incontinence, bilateral leg weakness or numbness. Surgical emergency — MRI immediately, neurosurgery consultation. Do not delay for outpatient workup.
- Radiculopathy (sciatica): pain radiating below the knee in a dermatomal distribution, associated with numbness, tingling, or weakness. L4: medial leg/foot, knee extension weakness. L5: dorsal foot, great toe extension weakness. S1: lateral foot, plantar flexion weakness. Positive straight leg raise (SLR) at <60 degrees is sensitive for disc herniation.
- Yellow flags (psychosocial risk factors for chronicity): fear-avoidance beliefs, catastrophizing, passive coping, job dissatisfaction, depression/anxiety, litigation. Identify early — psychosocial factors are stronger predictors of chronicity than imaging findings.
2 · Differential / Secondary Causes
Nonspecific low back pain (most common)
Mechanical, musculoligamentous strain. No neurologic deficit, no red flags. Self-limited. NSAIDs, heat, early return to activity. Avoid bed rest. Reassure — most resolve in 4–6 weeks.
Lumbar disc herniation with radiculopathy
Dermatomal leg pain, positive SLR. Most resolve without surgery in 6–12 weeks. NSAIDs, physical therapy. Epidural steroid injection for refractory radicular pain. Surgery (discectomy) for progressive neurologic deficit or failure of conservative management at 6–12 weeks.
Lumbar spinal stenosis
Neurogenic claudication: bilateral leg pain/weakness with walking, relieved by sitting or leaning forward (shopping cart sign). Older adults. MRI for diagnosis. Physical therapy, epidural steroids. Surgical decompression for severe or progressive symptoms.
Vertebral compression fracture
Acute back pain after minimal or no trauma in older adults or patients on chronic steroids. Osteoporosis risk factors. X-ray first (loss of vertebral height). MRI if X-ray equivocal or neurologic symptoms. DEXA scan. Vertebroplasty/kyphoplasty for refractory pain.
Spinal epidural abscess
Fever + back pain + neurologic deficit (classic triad, but often incomplete). IV drug use, recent spinal procedure, immunocompromised. MRI with contrast urgently. IV antibiotics (anti-staphylococcal coverage). Neurosurgery consultation — surgical drainage for neurologic compromise.
3 · Treatment Pathway
First-line: activity, heat, NSAIDs
Encourage early return to normal activity — bed rest worsens outcomes. Superficial heat (heating pad) is more effective than cold for acute LBP. NSAIDs (ibuprofen, naproxen) are first-line pharmacologic treatment. Acetaminophen has limited evidence for LBP but is safer for patients with GI or cardiovascular risk.
Muscle relaxants
Cyclobenzaprine or methocarbamol for acute LBP with muscle spasm. Short-term use (1–2 weeks). Sedating — avoid in older adults and patients who drive. Do not combine with opioids or benzodiazepines.
Physical therapy and exercise
Acute LBP: early mobilization and reassurance. Subacute/chronic LBP: structured physical therapy, core strengthening, McKenzie method. Yoga and tai chi have evidence for chronic LBP. Cognitive behavioral therapy (CBT) for chronic LBP with significant psychosocial overlay.
Avoid opioids for nonspecific LBP
Opioids are not recommended for acute nonspecific LBP — they do not improve outcomes and increase risk of dependence, falls, and chronic opioid use. If used at all, limit to the lowest effective dose for the shortest duration (<1 week) for severe acute pain not responsive to NSAIDs.
Imaging — when to order
Do NOT image acute nonspecific LBP in the first 4–6 weeks without red flags. Imaging findings (disc bulges, degenerative changes) are common in asymptomatic adults and do not predict pain or outcomes. Order MRI (preferred over CT) when red flags are present, neurologic deficit is progressive, or symptoms persist >6 weeks without improvement.
4 · Expected Response
- Acute nonspecific LBP: 90% of patients improve significantly within 4–6 weeks. Reassurance and activity are the most important interventions.
- Lumbar disc herniation with radiculopathy: 80–90% resolve without surgery within 6–12 weeks. Leg pain (radiculopathy) typically resolves before back pain.
- Epidural steroid injection for radiculopathy: short-term pain relief (weeks to months) but no long-term benefit over conservative management.
5 · Escalation
- Cauda equina syndrome (saddle anesthesia, bowel/bladder dysfunction, bilateral leg weakness): MRI immediately, emergent neurosurgery consultation. Surgical decompression within hours.
- Progressive neurologic deficit (worsening foot drop, increasing weakness): urgent MRI and neurosurgery consultation.
- Suspected spinal epidural abscess (fever + back pain + neurologic symptoms): MRI with contrast urgently, IV antibiotics, neurosurgery.
- Chronic LBP not responding to conservative management at 12 weeks: multidisciplinary pain program, pain management consultation, consider interventional procedures.
Apply It · Change One Detail
APPLY IT
A 38-year-old man presents with 5 days of acute low back pain after lifting. No leg pain, no neurologic symptoms, no red flags. He asks for an MRI. Imaging is not indicated — acute nonspecific LBP without red flags does not benefit from early imaging, and findings would not change management. Prescribe ibuprofen, recommend heat and early return to activity, and reassure that 90% of cases resolve in 4–6 weeks. Reassess at 4–6 weeks if not improving.
CHANGE ONE DETAIL
Change one detail — the same patient now reports difficulty urinating, perineal numbness, and bilateral leg weakness. This is cauda equina syndrome — a surgical emergency. Order MRI immediately and call neurosurgery. Do not wait for outpatient scheduling. Delay in decompression leads to permanent bowel, bladder, and motor deficits.
Bottom Line
Do not image acute nonspecific low back pain in the first 4–6 weeks — imaging findings do not predict pain or outcomes and increase the likelihood of unnecessary procedures. Cauda equina syndrome (saddle anesthesia, bowel/bladder dysfunction) is a surgical emergency requiring immediate MRI.
EVIDENCE & REFERENCES
- Qaseem A, et al. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians. Ann Intern Med. 2017;166(7):514-530. doi:10.7326/M16-2367
- Chou R, et al. 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(7):478-491. doi:10.7326/0003-4819-147-7-200710020-00006
- Deyo RA, et al. Overtreating Chronic Back Pain: Time to Back Off? J Am Board Fam Med. 2009;22(1):62-68. doi:10.3122/jabfm.2009.01.080102