What are the differential diagnoses and management options for a patient presenting with low back pain?

Low Back Pain: Differential Diagnoses and Management

Critical Red Flag Conditions (Require Immediate Action)

The first priority is to identify life-threatening or irreversible conditions through focused history and physical examination, as routine imaging without red flags does not improve outcomes and exposes patients to unnecessary radiation. 1, 2

Cauda Equina Syndrome (0.04% prevalence)

• Urinary retention, fecal incontinence, saddle anesthesia, and bilateral lower extremity motor deficits 2
• Requires immediate MRI and urgent neurosurgical consultation within hours 1, 3
• Delayed recognition leads to permanent neurologic disability 2

Vertebral Malignancy (0.7% prevalence)

• History of cancer increases probability from 0.7% to 9% (positive likelihood ratio 14.7) 2
• Look for: age >50, unexplained weight loss, failure to improve with conservative therapy 2
• Obtain MRI if suspected 1

Vertebral Compression Fracture (4% prevalence)

• Midline tenderness in patients with osteoporosis or chronic steroid use 1, 2
• Plain radiography is appropriate initial imaging 2
• MRI if neurologic compromise suspected 1

Spinal Infection

• Fever, recent invasive spinal procedure, IV drug use, or immunosuppression 1, 4
• Obtain MRI and blood cultures 1

Primary Diagnostic Categories

Nonspecific Mechanical Low Back Pain (>85% of cases)

• No identifiable structural pathology; pain arises from spine, discs, or soft tissues 2, 4
• Diagnosis of exclusion after ruling out red flags 4

Radiculopathy from Herniated Disc (4% prevalence)

• Sciatica with dermatomal sensory changes, positive straight leg raise, and specific motor weakness 2
• Most improve within 4 weeks with conservative management 2
• Urgent referral (within 2 weeks) if motor or sensory deficits present 3

Spinal Stenosis (3% prevalence)

• Pseudoclaudication: bilateral leg symptoms worsening with walking/standing, relieved by sitting/flexion 2
• Older age population 2
• Most improve with conservative management 2

Inflammatory Spondyloarthropathy

• Age <45 years, chronic symptoms >3 months, morning stiffness >30 minutes 2
• Missing this diagnosis delays access to highly effective TNF-blocking agents 2

Imaging Strategy

Do NOT obtain routine imaging for nonspecific low back pain without red flags—this does not improve outcomes and may lead to unnecessary interventions. 1, 2

When to Image:

• Red flags present: immediate MRI 1, 2
• Persistent symptoms after 4-6 weeks of conservative therapy: plain radiography first 1
• Progressive neurologic deficits: immediate MRI 1
• MRI superior to CT (avoids radiation, better soft tissue visualization) 1, 2

Critical Pitfall:

• Single lumbar spine x-ray delivers gonadal radiation equivalent to daily chest x-rays for >1 year 2
• Disc abnormalities common in asymptomatic patients—imaging findings must correlate with clinical presentation 3

Initial Management Algorithm

First Visit (All Patients Without Red Flags):

Advise staying active and avoiding bed rest—maintaining activity reduces disability and improves outcomes. 1, 5

1. Patient education and reassurance 1, 5
2. Superficial heat application (heating pads) 1
3. First-line medication: NSAIDs (moderate-quality evidence) 1, 6
   • Acetaminophen up to 4g daily for mild pain 1
   • Avoid opioids initially due to abuse potential and lack of superior efficacy 1

At 2 Weeks: Risk Stratification

Use the STarT Back tool to stratify patients and direct resources appropriately. 5, 1

Low-Risk Patients (minimal psychosocial barriers):

• Continue current management 5
• Ongoing evaluation 5

Medium-Risk Patients:

• Refer to physiotherapy 1
• Consider nonpharmacologic treatments: massage, acupuncture, or spinal manipulation 1

High-Risk Patients (anxiety, depression, catastrophizing, fear-avoidance, job dissatisfaction):

• Refer for comprehensive biopsychosocial assessment by multidisciplinary team 5, 1
• Review no later than 12 weeks 5
• Consider psychological interventions if psychosocial factors prominent 1

At 4-6 Weeks: Persistent Symptoms

If no improvement, consider plain radiography (if not previously done) and intensify nonpharmacologic therapy. 1

At 12 Weeks: Transition to Chronic Management

No improvement after 12 weeks warrants referral to specialist pain center or specialist spinal center. 5

Chronic Low Back Pain Management (>12 weeks)

First-Line: Nonpharmacologic Treatments

Exercise therapy, multidisciplinary rehabilitation, cognitive behavioral therapy, mindfulness-based stress reduction, tai chi, yoga, acupuncture, or spinal manipulation (moderate to low-quality evidence) 1, 6

Second-Line: Pharmacologic Escalation

• Continue NSAIDs 1
• Add tramadol or duloxetine if inadequate response 1, 6
• Opioids only as last resort with careful monitoring and lowest effective dose 1, 5

Avoid:

• Systemic corticosteroids (not recommended for long-term management) 1
• Benzodiazepines, muscle relaxants (inconclusive evidence) 6
• Epidural steroid injections except for short-term relief in radicular pain 6

Radicular Pain-Specific Management

Radicular pain requires different management than nonspecific low back pain and responds poorly to simple analgesics. 3

Initial Management:

• NSAIDs as first-line 3
• Consider neuropathic pain medications early (gabapentin, pregabalin) 3
• Avoid bed rest—staying active is superior 3

Referral Timing:

• Urgent (within 2 weeks) if disabling pain or any motor/sensory deficits 3
• By 3 months if symptoms persist despite conservative management 3
• Earlier if pain severity increases or functional disability worsens 3

Surgical Consideration:

• Minimum 6 weeks (ideally 3 months) of comprehensive conservative management required before surgical referral 3
• Indications: progressive neurological deficits, persistent functional disabilities despite multiple conservative treatments, or persistent radicular symptoms from confirmed disc herniation 3

Common Pitfalls to Avoid

1. Routine imaging for uncomplicated acute low back pain exposes patients to unnecessary radiation without clinical benefit 1, 2
2. Prescribing prolonged bed rest—this worsens outcomes 1, 3
3. Overreliance on opioid medications for pain management 1
4. Failing to assess psychosocial factors (yellow flags) that predict chronicity 1, 2
5. Overlooking inflammatory causes in younger patients (<45 years) with chronic symptoms and morning stiffness 2
6. Missing cauda equina syndrome leads to permanent disability from delayed decompression 2
7. Delayed treatment for progressive neurological deficits associates with worse outcomes 3