What are the differential diagnoses for left-sided neck, arm, and chest pain accompanied by left eyelid drooping on awakening?

Differential Diagnosis: Left-Sided Neck, Arm, and Chest Pain with Left Eyelid Drooping on Awakening

The most critical diagnosis to rule out immediately is left internal carotid artery dissection, which presents with this exact constellation of symptoms and requires urgent imaging to prevent stroke. 1

Priority Differential Diagnoses

1. Internal Carotid Artery Dissection (ICAD) - MOST URGENT

This is the classic presentation of the "ICAD triad": ipsilateral neck/head/orbital pain, Horner syndrome (causing eyelid ptosis), and potential cerebral/retinal ischemia 1.

Key clinical features:

• Pain in neck, chest, and arm on the same side as the ptosis
• Horner syndrome manifests as ptosis (drooping eyelid), miosis (smaller pupil), and sometimes anhidrosis (decreased sweating)
• Carotid dissection is the most common identifiable cause of Horner syndrome in acute presentations 2
• The ptosis may be transient and resolve within days, but the underlying dissection remains dangerous 1

Critical action: This requires immediate vascular imaging - CT angiography or MR angiography of the neck to visualize the carotid artery 2, 1. The preganglionic sympathetic pathway courses along the internal carotid artery, making dissection a direct cause of Horner syndrome 2.

2. Pancoast Tumor (Apical Lung Tumor)

The preganglionic sympathetic pathway travels through the pulmonary apex region (C8-T2 nerve roots, paraspinal and mediastinal regions) before synapsing at the superior cervical ganglia 2.

Key clinical features:

• Left-sided chest, shoulder, and arm pain
• Horner syndrome from tumor invasion of the sympathetic chain
• May have associated brachial plexopathy causing arm pain and weakness

Imaging needed: Chest CT or MRI to evaluate the lung apex and mediastinum 2.

3. Cervical Spine Pathology with Nerve Root Compression

While cervical radiculopathy commonly causes neck and arm pain, it does not typically cause Horner syndrome unless there is trauma or tumor involvement affecting the sympathetic chain 3.

Key distinguishing features:

• Radicular pain pattern following specific dermatomes
• Sensory or motor deficits in specific nerve root distributions
• The presence of Horner syndrome makes simple disc herniation unlikely

4. Trauma to Cervical Spine/Neck/Skull Base

Even minor trauma (including iatrogenic from procedures) can injure the sympathetic pathway 2.

Ask specifically about:

• Recent neck manipulation or chiropractic treatment
• Recent procedures (central lines, neck surgery)
• Any head or neck injury, even seemingly minor

5. Mediastinal or Paraspinal Mass

Tumors along the sympathetic chain pathway from the upper thoracic spine through the mediastinum can cause this presentation 2.

Immediate Workup Algorithm

Step 1: Assess acuity and perform targeted physical exam

• Check for anisocoria (pupil asymmetry) - smaller pupil on affected side
• Assess for facial anhidrosis
• Perform pharmacologic testing if available (apraclonidine or cocaine drops) to confirm Horner syndrome 1
• Examine for focal neurological deficits

Step 2: Urgent imaging based on presentation

For acute onset with pain (your patient):

• CT angiography or MR angiography of neck vessels - first priority to rule out dissection 2, 1
• Chest CT - to evaluate pulmonary apex and mediastinum for masses 2
• MRI of cervical spine and brachial plexus - if above are negative and symptoms persist 2

Step 3: If initial imaging negative

• High-resolution orbital MRI with pre- and post-contrast sequences to evaluate cavernous sinus, orbital apex, and skull base 2
• Consider dedicated brachial plexus MRI if arm symptoms predominate 2

Critical Pitfalls to Avoid

1. Do not dismiss transient ptosis - Horner syndrome from carotid dissection can resolve within days while the dissection remains and stroke risk persists 1

2. Do not attribute all neck and arm pain to "cervical radiculopathy" - The presence of Horner syndrome indicates sympathetic pathway involvement, which is NOT typical of simple disc herniation 2, 3

3. Do not delay imaging for "conservative management" - While 75-90% of cervical radiculopathy improves with conservative therapy 3, this patient has red flags (Horner syndrome) requiring immediate investigation

4. Do not order plain radiographs first - They are useless for evaluating the sympathetic pathway, vascular structures, or soft tissue masses 2, 3

The combination of unilateral neck/arm/chest pain with ipsilateral Horner syndrome is a medical emergency until carotid dissection is excluded. 2, 1