Causes of Acute Cervical Radiculopathy with Sudden Shoulder Pain
The most common causes of sudden-onset cervical radiculopathy with shoulder pain are cervical disc herniation (soft disc) and cervical spondylosis with osteophyte formation (hard disc) causing nerve root compression in the neural foramen. 1, 2
Primary Pathophysiologic Mechanisms
Compressive Causes
- Cervical disc herniation causes direct nerve root compression, typically presenting with acute onset of symptoms including neck pain radiating to the shoulder and arm in a dermatomal distribution 2, 3
- Cervical spondylosis with degenerative changes leads to foraminal narrowing through facet joint hypertrophy, uncovertebral joint hypertrophy, disc bulging, and osteophyte formation 1, 4
- Combined pathology is common, where both disc herniation and degenerative changes contribute to nerve root compression 1
Inflammatory Component
- Nerve root compression triggers an inflammatory cascade that amplifies pain beyond simple mechanical compression 3, 4
- The combination of compression and inflammation produces the characteristic "electric" quality of radicular pain that distinguishes it from other shoulder pain etiologies 5
Clinical Presentation Pattern
Typical Symptom Distribution
- Pain radiates from the neck to the shoulder and continues down the arm in a specific dermatomal pattern corresponding to the affected nerve root (most commonly C5-C6 or C7) 5, 1
- Sensory dysfunction manifests as numbness, tingling, or hypesthesia in the affected dermatome 2, 3
- Motor weakness occurs in specific muscle groups corresponding to the compressed nerve root 2, 3
- Reflex changes, particularly diminished triceps or biceps reflexes, are the most common objective neurologic findings 6
Distinguishing Features
- The dermatomal distribution of symptoms helps differentiate radiculopathy from peripheral nerve entrapment syndromes 5, 4
- Neck movements typically exacerbate symptoms, and muscle spasm is commonly present 6
- Spurling test (cervical compression with rotation) reproduces radicular symptoms 6
Red Flag Causes Requiring Urgent Evaluation
You must immediately consider these serious etiologies when evaluating sudden-onset cervical radiculopathy: 1
- Trauma - even minor trauma in older patients with degenerative changes
- Malignancy - primary or metastatic disease causing pathologic fracture or epidural compression
- Infection - epidural abscess or discitis, particularly with fever, elevated inflammatory markers, or IV drug use history
- Myelopathy - spinal cord compression presenting with bilateral symptoms, gait instability, or bowel/bladder dysfunction 5, 1
- Vascular pathology - vertebral artery dissection in patients >50 years with concomitant vascular disease 1
Atypical Presentations Suggesting Alternative Diagnoses
When Symptoms Don't Fit Classic Radiculopathy
- Bilateral symptoms or symptoms affecting both upper and lower extremities suggest cervical myelopathy (spinal cord compression) rather than simple radiculopathy 5
- Unilateral arm and leg symptoms together raise concern for either myelopathy with long tract signs or multiple levels of pathology affecting both cervical and lumbar spine 5
- Symptoms without dermatomal distribution suggest plexopathy or peripheral nerve entrapment rather than radiculopathy 5
Diagnostic Approach Algorithm
Initial Clinical Assessment
Perform targeted neurologic examination focusing on:
Screen for red flags that mandate immediate imaging:
- Progressive neurological deficits
- Bowel/bladder dysfunction or perineal sensory loss
- Constitutional symptoms (fever, weight loss, night sweats)
- History of malignancy or immunosuppression
- Severe trauma or minor trauma in elderly 1
Imaging Strategy
- In the absence of red flags, imaging is NOT required at initial presentation, as 75-90% of cases resolve with conservative management and degenerative changes correlate poorly with symptoms 1, 6
- MRI cervical spine without contrast is the preferred imaging modality when indicated, as it provides superior soft tissue visualization for detecting disc herniations and nerve root compression with 88% accuracy 7, 5, 2
- Critical pitfall: MRI abnormalities are extremely common in asymptomatic patients, so findings must correlate with clinical symptoms to guide treatment 7, 1
- CT cervical spine offers superior bone detail for assessing foraminal stenosis from osteophytes and facet hypertrophy but is less sensitive for disc herniations 7, 2
When to Order Imaging
- Immediate imaging (within 24-48 hours) for any red flag symptoms 1
- Delayed imaging (after 4-6 weeks) for persistent symptoms despite adequate conservative treatment 6, 8
- Consider MRI of both cervical and lumbar spine when symptoms affect both upper and lower extremities 5
Natural History and Prognosis
- 75-90% of patients improve with conservative management alone, regardless of specific treatment modality 1, 2, 8
- Most acute cases resolve spontaneously or with conservative measures within weeks to months 1
- The annual incidence is approximately 83.2 per 100,000, making it less common than general neck pain 1
Common Clinical Pitfalls to Avoid
- Ordering MRI too early: Degenerative changes are ubiquitous in patients >30 years and often don't correlate with symptoms 1
- Assuming MRI findings explain symptoms: High false-positive rate in asymptomatic individuals requires strict clinical correlation 7, 1
- Missing myelopathy: Bilateral symptoms, gait instability, or hyperreflexia indicate spinal cord compression requiring urgent evaluation 5, 1
- Overlooking peripheral nerve entrapment: Carpal tunnel syndrome, cubital tunnel syndrome, or thoracic outlet syndrome can mimic or coexist with radiculopathy 4, 6
- Premature surgical referral: Given the 75-90% success rate with conservative management, surgery should only be considered after adequate conservative trial (minimum 6 weeks) unless progressive neurologic deficits are present 1, 2