What are the differential diagnoses for a patient presenting with headache and a conjunctival (subconjunctival) hematoma?

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Differential Diagnosis for Headache with Conjunctival Hematoma

The most critical diagnosis to exclude immediately is subarachnoid hemorrhage (SAH), which can present with subconjunctival hemorrhage due to sudden elevation in intracranial pressure causing rupture of conjunctival vessels—this combination demands urgent neuroimaging and potentially lumbar puncture given the catastrophic morbidity and mortality of missed SAH. 1

Life-Threatening Diagnoses (Must Rule Out First)

Subarachnoid Hemorrhage

  • Mechanism: Sudden ICP spike during aneurysmal rupture causes conjunctival vessel rupture
  • Key features: Thunderclap headache (instantly peaking), neck stiffness, altered consciousness, onset during exertion
  • Workup algorithm 1:
    • If presenting within 6 hours of headache onset: Non-contrast head CT (98.7% sensitive)
    • If presenting >6 hours or CT negative with high suspicion: Lumbar puncture for xanthochromia (100% sensitive at 12 hours-2 weeks)
    • Apply Ottawa SAH Rule criteria: age ≥40, neck pain/stiffness, witnessed LOC, exertional onset, thunderclap quality, limited neck flexion
  • Critical pitfall: Atypical presentations (neck pain alone, syncope, seizure) still require full workup 1

Ruptured Cavernous Carotid Aneurysm with Carotid-Cavernous Fistula

  • Presentation: Initially benign headache that rapidly progresses to unilateral eye swelling, chemosis, conjunctival injection, blurred vision 2
  • Timeline: Can evolve overnight from simple headache to acute orbital compartment syndrome
  • Workup: CT angiography to identify cavernous sinus lesions and enlarged ophthalmic veins
  • Management: Emergent lateral canthotomy if orbital compartment syndrome develops, followed by endovascular intervention 2

Cerebral Venous Thrombosis (CVT)

  • Presentation: Progressive headache over days-weeks, papilledema, sixth nerve palsy, seizures (frequent distinguishing feature), focal deficits 3
  • Conjunctival findings: Increased ICP can cause conjunctival hemorrhage; dilated scalp veins may be visible
  • High-risk features: Pregnancy/postpartum, oral contraceptives, thrombophilia, infection (ear/sinus)
  • Workup: MR venography or CT venography 3

Moderate-Risk Diagnoses

Subdural Hematoma

  • Context: Can present with nonspecific headache; consider especially in elderly (>50 years), anticoagulated patients, or post-trauma 4, 5
  • Valsalva mechanism: Straining can cause both SDH and conjunctival hemorrhage
  • Workup: CT or MRI head
  • Atypical presentation: Can manifest with tinnitus and hearing loss 5

Hypertensive Crisis

  • Mechanism: Severe hypertension causes both headache and conjunctival vessel rupture
  • Key features: Blood pressure typically >180/120 mmHg, end-organ damage signs
  • Workup: Blood pressure measurement, fundoscopy for papilledema/hemorrhages

Benign Diagnoses (Diagnosis of Exclusion)

Isolated Subconjunctival Hemorrhage with Coincidental Primary Headache

  • Most common scenario: Trauma (83% of pediatric SCH) or conjunctivitis (13%) causing SCH, unrelated to headache etiology 6
  • Valsalva-induced: Coughing, choking, vomiting can cause isolated SCH (2% of cases) 6
  • Coagulopathy: Aspirin use, bleeding disorders (rare, 1-2% of cases) 6, 7

SUNCT Syndrome (Short-lasting Unilateral Neuralgiform headache with Conjunctival injection and Tearing)

  • Presentation: Strictly unilateral periocular pain, 10-120 second duration, with conjunctival injection and tearing 8
  • Key distinction: Conjunctival injection (not hemorrhage), but can be confused
  • Demographics: Males, age ~50 years
  • Workup: MRI to exclude posterior fossa lesions (vascular malformations can mimic SUNCT) 8

Algorithmic Approach

Step 1: Assess for SAH red flags using Ottawa SAH Rule 1

  • If ANY criterion met → Urgent non-contrast head CT
  • If CT negative and >6 hours from onset → LP for xanthochromia

Step 2: If SAH excluded, examine for orbital/ocular emergency 2

  • Rapidly progressive eye swelling, chemosis, vision changes → CTA for cavernous sinus pathology
  • Proptosis, ophthalmoplegia → Consider orbital compartment syndrome

Step 3: Assess for CVT risk factors 3

  • Pregnancy/postpartum, OCP use, thrombophilia, progressive headache → MR/CT venography

Step 4: Age-specific considerations 4

  • Age >50 with new headache → Consider temporal arteritis (ESR/CRP), subdural hematoma, mass lesion
  • Obtain neuroimaging liberally in this population (15% have serious pathology)

Step 5: If all imaging negative, consider benign causes 6

  • Document trauma history, Valsalva events, medication use (anticoagulants)
  • Examine for signs of conjunctivitis or other ocular surface inflammation

Critical Pitfalls to Avoid

  • Never dismiss thunderclap headache with normal CT alone if presenting >6 hours from onset—LP is mandatory 1
  • Don't attribute SCH to "straining" without excluding SAH in patients with severe headache
  • Recognize that CT sensitivity for SAH drops dramatically after 24 hours (95% day 0 → 50% at 1 week) 4
  • Consider imaging even with "benign" exam in patients >50 years given 15% rate of serious pathology 4

References

2
Research

Swollen and bloodshot eye following headache.

The American journal of emergency medicine, 2019

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