What is the diagnostic workup and management for a patient with a probable herniated disc?

Diagnostic Workup and Management for Probable Herniated Lumbar Disc

Initial Clinical Assessment

For a patient with probable herniated disc, perform a focused history and physical examination to classify them into one of three categories: nonspecific low back pain, radiculopathy/spinal stenosis, or another specific spinal cause requiring urgent evaluation. 1

Critical Red Flags Requiring Immediate Imaging

• Urinary retention (90% sensitivity for cauda equina syndrome) 2
• Saddle anesthesia, fecal incontinence, or bilateral lower extremity weakness 2
• Progressive motor deficits at multiple levels 1
• History of cancer, unexplained weight loss, fever, or age >50 years with new-onset pain 1

Physical Examination Findings for L5 Radiculopathy (Most Common)

• Weakness in foot dorsiflexion and great toe extension 2
• Sensory changes along the lateral leg and dorsum of the foot 2
• Radicular pain radiating down the posterolateral thigh and lateral leg to the dorsum of the foot 2

Diagnostic Imaging Algorithm

When NOT to Order Imaging

Do not order imaging for acute low back pain with radiculopathy in the first 4-6 weeks unless red flags are present. 1, 2, 3 The natural history shows improvement within the first 4 weeks with conservative management in most patients 2, and most disc herniations demonstrate spontaneous reabsorption by 8 weeks 2.

When to Order Imaging

Order MRI lumbar spine without contrast if:

• Radicular symptoms persist beyond 4-6 weeks despite conservative therapy AND the patient is a surgical or epidural injection candidate 1, 3
• Any red flags are present (cauda equina syndrome, progressive neurological deficits, suspected malignancy/infection) 1, 3

Imaging Modality Selection

MRI lumbar spine without contrast is the preferred initial imaging modality 1, 2, 3, with 96% accuracy compared to surgical findings 4 and superior sensitivity (91.7%) and specificity (100%) compared to CT 5.

If MRI is delayed >2-4 weeks or contraindicated:

• CT lumbar spine without contrast is a reasonable alternative, with >80% sensitivity and specificity for most lumbar pathologies 3
• CT demonstrates 77.4% accuracy compared to surgical findings 5

Reserve MRI with and without contrast for:

• Suspected underlying malignancy, infection, or inflammation 1

Conservative Management Protocol

First-Line Treatment (Initial 4-6 Weeks)

Advise patients to remain active; bed rest is inferior to activity 2. Bed rest should be brief, often less than 1 week 6.

Pharmacologic management:

• NSAIDs and acetaminophen for pain control 2
• Muscle relaxants and narcotic analgesics have limited roles and should be strictly time-limited 6

Avoid ineffective interventions:

• Conventional traction and corsets are probably ineffective 6

Psychosocial Assessment

Assess psychosocial risk factors including depression, anxiety, job dissatisfaction, pending litigation/workers' compensation, catastrophizing, and fear-avoidance behaviors 2, as these predict risk for chronic disabling back pain 1.

Surgical Indications

Surgery is appropriate when:

• Conservative therapy has failed after 4-6 weeks 2
• Progressive neurological deficits are present 2
• Suspected cauda equina syndrome 2
• Combination of definite disc herniation on imaging, corresponding sciatic pain syndrome, corresponding neurologic deficit, and failure to respond to 6 weeks of conservative therapy 6

Only 5-10% of patients with symptomatic disc herniation require surgery 6, as most resolve with conservative therapy 6.

Critical Pitfalls to Avoid

Do not base treatment decisions on imaging findings alone. Clinical correlation between symptoms and imaging findings is essential 2, as up to 20-28% of asymptomatic individuals have disc herniations on imaging 3.

Except for cauda equina syndrome, surgery is generally inappropriate without:

• Documented failure of 6 weeks of conservative therapy 6
• Corresponding neurologic deficit matching imaging findings 6

Interventional Options

Epidural steroid injections may be considered for persistent radicular symptoms after failed conservative therapy 2, but only in patients who are potential candidates for this intervention 3.