What are the differential diagnoses for intermittent numbness, tingling, and shooting pain down both arms that worsens with neck flexion (chin‑to‑chest) in a patient with stable vital signs and no fever or chills?

Differential Diagnosis for Bilateral Arm Symptoms with Positive Neck Flexion Sign

This patient is exhibiting a positive Lhermitte's sign (electric shock-like pain radiating down both arms with neck flexion), which is highly suggestive of cervical myelopathy or cervical radiculopathy affecting multiple nerve roots bilaterally. The bilateral nature and provocation with neck flexion narrows the differential significantly toward spinal cord or multi-level nerve root pathology.

Primary Differential Diagnoses

1. Cervical Myelopathy

• Most concerning diagnosis given bilateral symptoms and positive Lhermitte's sign, which indicates spinal cord irritation 1
• Caused by spinal cord compression from:
  • Cervical spondylosis with spinal stenosis
  • Herniated disc with cord compression
  • Ossification of posterior longitudinal ligament (OPLL)
• Look for additional myelopathic signs: gait disturbance, lower extremity weakness, hyperreflexia, positive Hoffman's sign, clonus, or bowel/bladder dysfunction 1

2. Bilateral Cervical Radiculopathy

• Cervical nerve root impingement at multiple levels causing bilateral upper limb pain and sensorimotor deficits 1
• Can result from:
  • Multi-level disc herniations
  • Severe spondylosis with bilateral foraminal stenosis
  • Facet joint hypertrophy with bilateral nerve root compression
• Characterized by dermatomal pain distribution, with 75-90% achieving symptomatic relief with conservative therapy 1
• Annual incidence of 83 per 100,000 persons 1

3. Central Disc Herniation

• Large central cervical disc herniation can cause bilateral symptoms by compressing the spinal cord or bilateral nerve roots 1
• Soft disc pathology is a common cause of cervical radiculopathy 1

4. Cervical Spinal Stenosis

• Narrowing of the spinal canal causing bilateral cord or nerve root compression 1
• Often degenerative in nature with contributions from disc bulging, ligamentum flavum hypertrophy, and facet arthropathy

Secondary Considerations (Less Likely but Important)

5. Multiple Sclerosis or Demyelinating Disease

• Lhermitte's sign is classically associated with MS, though typically presents with other neurological findings 2
• Consider if patient has history of other neurological episodes or visual disturbances

6. Syringomyelia

• Fluid-filled cavity within spinal cord can cause bilateral symptoms 2
• Often presents with dissociated sensory loss (loss of pain/temperature with preserved light touch)

7. Spinal Cord Tumor

• Intramedullary or extramedullary tumors can cause progressive bilateral symptoms 1
• This is a "red flag" symptom requiring urgent evaluation 1

8. Inflammatory/Autoimmune Conditions

• Transverse myelitis, sarcoidosis, or other inflammatory conditions affecting the cervical cord 1
• Consider if there are systemic symptoms or elevated inflammatory markers (ESR, CRP) 1

Critical "Red Flag" Assessment

The bilateral nature of symptoms with positive Lhermitte's sign constitutes a neurological "red flag" requiring urgent imaging 1. Additional red flags to assess include:

• Progressive weakness or sensory loss 1
• Gait disturbance or falls 1
• Bowel or bladder dysfunction 1
• Constitutional symptoms (fever, weight loss, night sweats) 1
• History of malignancy 1
• Immunosuppression or IV drug use (infection risk) 1
• Coagulopathy 1

Diagnostic Approach

Clinical Examination Priorities

• Motor examination: Test upper and lower extremity strength, looking for specific myotomal patterns 1
• Sensory examination: Map dermatomal distribution of numbness/tingling 2, 3
• Reflexes: Assess for hyperreflexia (suggests myelopathy) vs. hyporeflexia (suggests radiculopathy) 1
• Myelopathic signs: Hoffman's sign, inverted radial reflex, clonus, Babinski sign 1
• Gait assessment: Observe for spastic or ataxic gait 1
• Spurling's test: Neck extension with lateral rotation and axial compression may reproduce radicular symptoms 1

Imaging Recommendations

Given the bilateral symptoms and positive Lhermitte's sign, this patient has neurological "red flags" warranting immediate MRI 1:

• MRI cervical spine without contrast is the imaging modality of choice for evaluating suspected myelopathy or multi-level radiculopathy 1
• MRI provides superior soft tissue visualization including spinal cord, nerve roots, discs, and ligaments 1
• Do not delay imaging with plain radiographs first in the presence of neurological symptoms 1
• CT myelography is an alternative if MRI is contraindicated 1

Important Diagnostic Caveats

• Physical examination has limited accuracy for diagnosing cervical radiculopathy in isolation 1
• MRI findings must be correlated with clinical presentation, as asymptomatic abnormalities are common (53.9% of adults show disc degeneration) 1
• MRI alone should not be used to diagnose symptomatic cervical radiculopathy due to frequent false-positives and false-negatives 1
• Diagnosis requires combination of clinical history, physical examination, and imaging 1

Clinical Pitfalls to Avoid

• Do not dismiss bilateral symptoms as "just arthritis" – bilateral upper extremity symptoms with Lhermitte's sign require urgent evaluation for myelopathy 1
• Do not obtain plain radiographs as initial imaging when neurological symptoms are present 1
• Do not assume symptoms are peripheral nerve entrapment (e.g., carpal tunnel syndrome) when bilateral and provoked by neck movement 4
• Do not delay referral to neurosurgery or spine specialist if myelopathy is suspected clinically 1