What is the diagnosis and management for a patient presenting with lower back pain radiating to the legs and buttocks?

Diagnosis: Lumbar Radiculopathy or Spinal Stenosis

The most likely diagnosis for a patient presenting with lower back pain radiating to the legs and buttocks is lumbar radiculopathy or spinal stenosis, characterized by sciatica (pain radiating below the knee in the sciatic nerve distribution) or neurogenic claudication (leg pain with walking/standing relieved by sitting). 1

Initial Diagnostic Approach

Conduct a focused history and physical examination to classify the patient into one of three categories: nonspecific low back pain, back pain with radiculopathy/spinal stenosis, or back pain with another specific spinal cause. 1

Critical Red Flags to Assess Immediately

Evaluate for emergent conditions requiring urgent imaging:

• Cauda equina syndrome: Urinary retention (90% sensitivity), fecal incontinence, bilateral leg weakness, saddle anesthesia 1
• Cancer risk factors: History of cancer (increases probability from 0.7% to 9%), unexplained weight loss, age >50 years, failure to improve after 1 month 1
• Infection indicators: Fever, IV drug use, immunosuppression 1
• Severe/progressive neurologic deficits: Motor weakness at multiple levels, rapidly worsening symptoms 1

Key Physical Examination Findings

• Straight-leg-raise test: Positive when sciatica is reproduced at 30-70 degrees of hip flexion with knee extended; crossed straight-leg-raise (pain in affected leg when lifting unaffected leg) is highly specific for nerve root compression 1
• Neurologic examination: Test for motor weakness, sensory deficits, and diminished reflexes in specific nerve root distributions 1
• Assess for spinal stenosis: Neurogenic claudication symptoms (leg pain with standing/walking, relieved by sitting or spinal flexion) 1

Imaging Strategy

Do NOT routinely obtain imaging for nonspecific low back pain without red flags. 1

Obtain urgent MRI (preferred) or CT if:

• Severe or progressive neurologic deficits are present 1
• Red flags suggest cancer, infection, or cauda equina syndrome 1, 2
• History of cancer warrants urgent MRI as primary test 2

For persistent radicular symptoms (>4 weeks) without red flags:

• Order MRI or CT only if the patient is a potential candidate for surgery or epidural steroid injection 1
• The natural history of disc herniation with radiculopathy shows improvement within 4 weeks in most patients with conservative management 1

Initial Management

Patient Education and Activity Modification

Advise patients to remain active rather than bed rest, which is more effective for acute and subacute low back pain. 1

• Inform patients of the generally favorable prognosis, with high likelihood of substantial improvement within the first month 1
• Explain that early routine imaging does not improve outcomes and incurs unnecessary costs 1

First-Line Pharmacologic Treatment

Start with acetaminophen or NSAIDs as first-line medications. 1

• Assess baseline pain severity, functional deficits, and contraindications before initiating therapy 1
• NSAIDs are the initial medication of choice for chronic symptoms 3, 4
• Consider tramadol or duloxetine for patients not responding to NSAIDs 3, 4

Nonpharmacologic Interventions

For acute pain: Consider spinal manipulation 1

For chronic or subacute pain (>4 weeks): Consider:

• Intensive interdisciplinary rehabilitation 1
• Exercise therapy 1, 4
• Acupuncture 1, 3
• Massage therapy 1, 3
• Cognitive-behavioral therapy 1
• Yoga or progressive relaxation 1

Common Pitfalls to Avoid

• Do not order MRI for every patient with leg pain: Imaging findings like bulging discs are often nonspecific and poorly correlate with symptoms 1
• Avoid muscle relaxants as first-line: Evidence is inconclusive for their benefit, and cyclobenzaprine carries risks of serotonin syndrome when combined with SSRIs, SNRIs, or tramadol 5, 4
• Do not prescribe long-term opioids: Evidence does not support their use in chronic low back pain 4
• Recognize that most patients improve without surgery: Reserve surgical evaluation for those with persistent functional disabilities despite conservative treatment or progressive neurologic deficits 1, 3, 4

Specific Diagnoses Within This Category

Lumbar radiculopathy (sciatica): Pain radiating below the knee, positive straight-leg-raise, dermatomal sensory loss, myotomal weakness, or reflex changes 1

Spinal stenosis: Neurogenic claudication pattern, typically in older patients, symptoms worse with standing/walking and relieved by sitting or forward flexion 1

Symptomatic herniated disc: Present in approximately 4% of primary care patients with low back pain 1