What is the most appropriate initial step for a patient presenting with 10 days of fever, severe frontal headache, nasal congestion, peri-orbital swelling, limited ocular movement, and frontal tenderness?

Immediate CT Imaging is the Most Appropriate Initial Step

This patient requires urgent CT imaging of the paranasal sinuses and orbits with IV contrast before initiating antibiotics, as the clinical presentation strongly suggests complicated acute bacterial rhinosinusitis with orbital and potentially intracranial extension. 1

Clinical Reasoning for Imaging Priority

This patient presents with classic "red flag" features that mandate immediate imaging:

• Peri-orbital swelling and limited ocular movement indicate orbital complications, most likely subperiosteal abscess or orbital cellulitis 1
• Severe frontal headache with frontal tenderness after 10 days of symptoms suggests frontal sinusitis with potential intracranial extension 1
• Duration of 10 days meets criteria for acute bacterial rhinosinusitis rather than viral illness 1

The ACR Appropriateness Criteria explicitly state that CT maxillofacial with IV contrast is the first-line imaging examination for patients with acute rhinosinusitis and suspected intraorbital and intracranial complications 1. The guidelines emphasize that imaging should be performed urgently when symptoms suggest orbital involvement including eye swelling, impaired eye movement, or decreased visual acuity 1.

Why CT Before Antibiotics

While antibiotics will ultimately be necessary, imaging must be obtained first for several critical reasons:

• Surgical planning: Orbital complications (subperiosteal abscess, orbital abscess) and intracranial complications (epidural abscess, subdural empyema) often require urgent surgical drainage in addition to antibiotics 1
• Mortality risk: Intracranial complications from frontal sinusitis carry significant morbidity and mortality, with frontal sinusitis being the most common source of intracranial spread 1
• Diagnostic accuracy: CT with contrast has 87% accuracy for detecting intracranial complications, and is essential for identifying the extent of orbital involvement 1

Specific Imaging Protocol

Order CT maxillofacial (paranasal sinuses) with IV contrast 1. This protocol:

• Provides excellent visualization of both bony sinus anatomy and soft tissue complications 1
• Typically includes orbital structures in the field of view 1
• Can identify subperiosteal abscess, orbital cellulitis, and early intracranial extension 1

Consider adding CT head with IV contrast if there is high suspicion for intracranial complications based on the severity of headache and systemic symptoms 1.

Common Pitfall to Avoid

Do not treat this as uncomplicated acute bacterial rhinosinusitis 1. The AAO-HNS guidelines clearly state that imaging is unnecessary for uncomplicated acute rhinosinusitis 1, but this patient has complicated disease with orbital signs. Starting antibiotics without imaging in this scenario risks:

• Missing a surgical emergency (abscess requiring drainage) 1
• Delayed diagnosis of cavernous sinus thrombosis, which can arise from frontal or ethmoid sinusitis 1
• Progression to life-threatening intracranial complications including meningitis, epidural abscess, or subdural empyema 1, 2

Immediate Management Algorithm

1. Obtain urgent CT maxillofacial with IV contrast (add CT head with contrast if severe headache or neurologic signs) 1
2. Simultaneously consult otolaryngology and ophthalmology while awaiting imaging 1
3. Initiate broad-spectrum IV antibiotics immediately after imaging (amoxicillin-clavulanate 1.5-3.0g IV every 6 hours or alternative regimen for complicated infection) 3
4. Proceed to surgical drainage if imaging confirms abscess (subperiosteal abscess ≥1.2cm width or any orbital abscess typically requires intervention) 4

Why This Prioritization Saves Lives

Frontal sinusitis with orbital complications represents a surgical emergency 1. Historical data show that delay in treatment of sphenoid and frontal sinusitis is always associated with serious morbidity or mortality, including fatal complications such as cavernous sinus thrombosis and bacterial meningitis 2. The pediatric literature confirms that early surgical intervention (within 48 hours) significantly decreases length of stay compared to late intervention 4, and similar principles apply to adults with complicated sinusitis.

The answer is A (CT), not B (antibiotics alone) - though both will ultimately be needed, imaging must come first to guide appropriate surgical versus medical management and prevent catastrophic complications.