What is the differential diagnosis for a patient presenting with left-sided upper back pain and neck pain?

Differential Diagnosis for Left-Sided Upper Back and Neck Pain

Immediate Red Flag Assessment

The first priority is to systematically screen for serious pathology requiring urgent intervention, as delayed diagnosis of conditions like epidural abscess or vertebral osteomyelitis can lead to permanent neurologic injury or death. 1

Critical Red Flags Requiring Urgent Evaluation

• Fever with new or worsening neck/back pain suggests vertebral osteomyelitis or epidural abscess 1
• Elevated inflammatory markers (ESR or CRP) indicate possible infection or inflammatory process 1, 2
• Constitutional symptoms including unexplained weight loss, night sweats, or malaise suggest malignancy or infection 3
• Risk factors for infection: IV drug use, diabetes, immunosuppression (HIV, steroids), recent spine procedure, indwelling catheters, or dialysis 1
• History of malignancy raises concern for metastatic disease to spine 3
• Recent bloodstream infection, particularly Staphylococcus aureus, strongly suggests vertebral osteomyelitis 1
• Progressive neurologic deficits including weakness, sensory changes, or bladder/bowel dysfunction indicate cord compression or cauda equina syndrome 1, 3

Primary Differential Diagnosis Categories

Mechanical/Degenerative Causes (Most Common)

Nonspecific neck and upper back pain accounts for over 85% of cases and represents mechanical pain from spine and supporting structures. 1

• Cervical radiculopathy from herniated disc or osteophyte compressing nerve roots, typically causing radiating arm pain in dermatomal distribution 1, 3, 4
• Facet joint arthropathy causing localized mechanical pain that may be unilateral 3
• Cervical degenerative disc disease (though degenerative changes correlate poorly with symptoms and are common in asymptomatic individuals) 1, 2
• Myofascial pain syndrome from muscle strain or spasm 1
• Cervical spondylosis with or without foraminal stenosis 1

Infectious Causes (Urgent)

Vertebral osteomyelitis and epidural abscess have increased in incidence (2.5-3 per 10,000 patients for epidural abscess) and are associated with diagnostic delay leading to significant morbidity and mortality. 1

• Vertebral osteomyelitis/discitis presents with back/neck pain, fever (present in only 45% of bacterial cases), elevated ESR/CRP, and risk factors 1
• Epidural abscess requires high suspicion in patients with preexisting infection source, immunosuppression, or elevated ESR 1
• Paraspinal abscess may accompany vertebral infection 1
• Tuberculosis or Brucella should be considered in endemic areas or with subacute presentation 1

Neoplastic Causes (Urgent)

• Metastatic disease to cervical/thoracic spine presents with intractable pain, constitutional symptoms, vertebral body tenderness 3
• Primary spinal tumors cause progressive symptoms refractory to conservative treatment 3
• Epidural compression syndrome from tumor requires urgent evaluation 5

Inflammatory/Autoimmune Causes

• Ankylosing spondylitis (prevalence 0.3-5% in primary care patients with back pain) 1
• Other inflammatory arthropathies presenting with persistent pain and elevated inflammatory markers 3

Vascular Causes

• Cervical artery dissection should be considered with acute onset, particularly with trauma history 1

Referred Pain Sources

• Cardiac ischemia can present as left upper back/neck pain 1
• Pulmonary pathology (pneumonia, pleurisy) may cause upper back pain 1
• Gastrointestinal sources (pancreatitis, peptic ulcer disease) can refer to upper back 1

Diagnostic Approach Algorithm

Step 1: History and Physical Examination

Obtain focused history specifically targeting red flags, duration of symptoms, neurologic symptoms, and risk factors for serious pathology. 1

• Assess for fever, constitutional symptoms, trauma history 1, 3
• Evaluate for radicular symptoms (dermatomal pain, numbness, weakness) 1, 4
• Identify risk factors: IV drug use, immunosuppression, malignancy history, recent procedures 1
• Perform motor/sensory neurologic examination 1
• Palpate spine for vertebral body tenderness 3

Step 2: Laboratory Testing (If Red Flags Present)

Obtain blood cultures (2 sets), ESR, and CRP in all patients with suspected infection. 1

• Blood cultures before antibiotics if infection suspected 1
• ESR and CRP (elevated in infection, malignancy, inflammatory conditions) 1, 2
• Complete blood count 3
• Consider PPD or interferon-γ release assay for subacute cases in endemic areas 1

Step 3: Imaging Strategy

MRI of the cervical/thoracic spine without and with contrast is the gold standard for evaluating suspected serious pathology, with sensitivity of 96% and specificity of 94% for spine infection. 1

When to Image Urgently:

• Any red flags present (fever, elevated inflammatory markers, neurologic deficits, constitutional symptoms, risk factors) 1, 2, 3
• Suspected infection, malignancy, or cord compression 1

MRI Indications:

• First-line imaging for suspected infection, tumor, cord compression, or radiculopathy with red flags 1, 2
• Superior tissue characterization and anatomic delineation 1
• Can evaluate entire spine if multilevel involvement suspected 1

CT Indications:

• When MRI contraindicated (pacemaker, cochlear implants, severe claustrophobia) 1
• Excellent osseous detail but low sensitivity (6%) for epidural abscess 1
• Useful for presurgical planning and guiding biopsy 1

When Imaging NOT Indicated:

• Acute nonspecific neck pain (<6 weeks) without red flags typically resolves spontaneously and does not require imaging. 1, 3
• Chronic pain (>12 weeks) without red flags may warrant imaging but is not urgent 1

Critical Clinical Pitfalls

• Fever is absent in up to 55% of bacterial vertebral osteomyelitis cases—do not rely on fever alone to rule out infection 1
• Degenerative changes on imaging are common in asymptomatic individuals and correlate poorly with symptoms—do not attribute pain to incidental findings without clinical correlation 1, 2
• Average time to diagnosis of vertebral osteomyelitis is 2-4 months, with 34% initially misdiagnosed—maintain high index of suspicion 1
• CT has only 6% sensitivity for epidural abscess—use MRI when infection suspected 1
• Imaging has limited value in whiplash-associated disorder without red flags—clinical assessment guides management 1, 6