What are the differential diagnoses and initial work‑up for acute posterior neck pain?

Differential Diagnosis for Acute Posterior Neck Pain

For acute posterior neck pain without red flags, the most common causes are mechanical—cervical muscle strain, facet joint arthropathy, and degenerative disc disease—and imaging is not indicated because most cases resolve spontaneously within 6–8 weeks with conservative management. 1

Primary Mechanical Causes (Most Common)

Musculoskeletal strain is the leading cause of acute posterior neck pain, arising from muscle overuse, poor posture, or minor trauma. 2

Facet joint arthropathy produces localized mechanical pain that may be unilateral and is exacerbated by extension or rotation. 3

Cervical spondylosis and degenerative disc disease are extremely common (affecting 53.9% of adults aged 18–97), though degenerative changes correlate poorly with symptoms and are present in 85% of asymptomatic individuals over age 30. 3, 1

Cervical radiculopathy from disc herniation or osteophyte compression of nerve roots presents with radiating arm pain, numbness, or weakness in a dermatomal distribution; 75–90% resolve with conservative therapy. 3, 4

Serious Etiologies Requiring Urgent Evaluation ("Red Flags")

Infectious

Vertebral osteomyelitis or discitis presents with fever, night sweats, elevated inflammatory markers (ESR, CRP, leukocytosis), and risk factors including IV drug use or immunosuppression; these patients require urgent MRI and blood cultures. 3, 1

Malignant

Metastatic disease to cervical vertebrae manifests as severe, intractable pain unresponsive to conservative therapy, constitutional symptoms (unexplained weight loss, night sweats), and vertebral body tenderness on palpation; history of prior malignancy mandates immediate MRI. 3, 1

Primary spinal tumors cause progressive symptoms refractory to treatment and require urgent imaging. 3

Neurological

Cervical myelopathy from spinal cord compression presents with progressive weakness, gait disturbance, hyperreflexia, and bowel/bladder dysfunction; this is a neurosurgical emergency requiring MRI within 12–24 hours. 3, 5

Inflammatory

Inflammatory arthritis (rheumatoid arthritis, ankylosing spondylitis) causes persistent neck pain with elevated inflammatory markers and morning stiffness. 3, 1

Vascular

Cervical arterial dissection presents with sudden-onset unilateral neck pain and headache, often with Horner syndrome or stroke symptoms; this requires urgent vascular imaging. 3

Traumatic

Pathologic fracture from osteoporosis or malignancy causes sudden severe pain after minimal or no trauma, worsened by axial loading. 3

Mandatory Red-Flag Screening

Every patient with acute posterior neck pain must be systematically screened for the following red flags, any one of which mandates immediate MRI of the cervical spine without contrast: 1, 3

• Constitutional symptoms: fever, unexplained weight loss, night sweats 1, 3
• Laboratory abnormalities: elevated ESR, CRP, or leukocytosis 1, 3
• History of malignancy (any prior cancer diagnosis) 1, 3
• Immunosuppression: HIV, chronic steroids, chemotherapy, organ transplant 1, 3
• Current or past IV drug use (even if currently denied) 1, 3
• Progressive neurological deficits: new weakness, sensory changes, gait disturbance, bowel/bladder dysfunction 1, 3
• Intractable pain despite 6–8 weeks of appropriate conservative therapy 1, 3
• Vertebral body tenderness on palpation 1, 3
• Recent trauma (even minor in elderly or osteoporotic patients) 3
• Coagulopathy on screening labs 3
• Age >50 years with concomitant vascular disease 1

Initial Work-Up Algorithm

Step 1: Red-Flag Assessment

Perform systematic red-flag screening on every patient. 1, 3

• If ANY red flag is present: Order urgent MRI cervical spine without contrast (within 12–24 hours if neurological deficits present) and do not delay imaging while awaiting specialist consultation. 1, 3

• If NO red flags: Proceed to conservative management without imaging. 1

Step 2: Conservative Management (No Red Flags)

For acute neck pain (<6 weeks) without red flags, initiate multimodal conservative therapy without imaging because most cases resolve spontaneously and plain radiographs rarely change management. 1, 2

Pharmacologic therapy:

• NSAIDs (ibuprofen, naproxen) for anti-inflammatory effect and pain control 3
• Acetaminophen when NSAIDs are contraindicated 3
• Short-term muscle relaxants (≤2 weeks) for severe spasm, with caution regarding sedation 3, 2
• Avoid opioids for acute mechanical neck pain due to unfavorable risk-benefit profile 3

Physical therapy and activity modification:

• Structured PT focusing on cervical range of motion, postural correction, and strengthening 3
• Avoid prolonged static neck positions and overhead activities 3
• Implement ergonomic workplace adjustments 3

Step 3: Re-evaluation at 6–8 Weeks

If symptoms persist beyond 6–8 weeks of appropriate conservative therapy, order MRI cervical spine without contrast to evaluate for structural pathology. 1, 3

If symptoms worsen or new red flags develop at any time, immediately order MRI. 1, 3

Step 4: Specialist Referral

Refer to spine surgery (neurosurgery or orthopedic spine) when: 3

• Symptoms persist beyond 6–8 weeks despite conservative therapy
• Progressive neurological deficits develop
• MRI reveals significant pathology (moderate-to-severe foraminal stenosis, disc herniation with nerve root compression, spinal cord compression)

Critical Pitfalls to Avoid

Do not order imaging for acute neck pain in the absence of red flags—this leads to overdiagnosis of incidental degenerative changes that are present in 85% of asymptomatic adults over 30 and correlate poorly with symptoms. 1

Do not interpret degenerative changes on imaging as causative without clinical correlation—a 10-year longitudinal MRI study showed 85% of patients had progression of cervical disc degeneration but only 34% developed symptoms. 1

Do not delay MRI when red flags are present—missing serious pathology such as infection, malignancy, or cord compression can result in irreversible neurological damage. 3, 5

Do not rely on plain radiographs alone when red flags are present—they cannot exclude metastasis, infection, or epidural disease. 3

Recognize that approximately 50% of patients will have residual or recurrent symptoms at 1 year, but this does not change the initial decision to defer imaging in the absence of red flags. 1, 3