Periorbital Ecchymosis in Basilar Skull Fractures
Basilar skull fractures classically present with bilateral periorbital ecchymosis ("raccoon eyes"), though the presence of this sign is neither sensitive nor specific for the diagnosis. 1, 2
Key Clinical Characteristics
Bilateral presentation is the hallmark feature when periorbital ecchymosis results from basilar skull fracture, distinguishing it from direct orbital trauma which may be unilateral. 3, 4 The bilateral pattern occurs because blood tracks along tissue planes from the skull base into periorbital tissues on both sides. 1
Anatomical Distinction: True "Raccoon Eyes"
The classic "raccoon eyes" or "panda sign" associated with basilar skull fractures demonstrates tarsal sparing—the bruising stops at the tarsal plate due to the orbital septum limiting blood spread. 3 This anatomical feature differentiates basilar skull fracture from:
- Direct orbital trauma (spreads beyond tarsal plate)
- Non-traumatic medical conditions causing periorbital bruising
- Vomiting-induced periorbital ecchymosis 3
Critical Diagnostic Limitations
The clinical signs of basilar skull fracture have poor diagnostic performance and should not guide critical management decisions. 2 In a prospective study of 136 blunt head trauma patients:
- Early detection accuracy: only 55.9%
- Specificity: 52.8%
- Positive predictive value: 25.7% 2
Common pitfall: Clinicians often overestimate the reliability of periorbital ecchymosis for basilar skull fracture diagnosis. In one trauma series, only 15 of 36 patients (42%) with periorbital ecchymosis actually had basilar skull fractures—the remainder had soft tissue injuries, convexity fractures, or facial fractures without skull base involvement. 1
Associated Clinical Features to Assess
When bilateral periorbital ecchymosis is present, immediately evaluate for:
- Cranial nerve injury (most common associated finding, present in 10 of 36 patients with periorbital ecchymosis) 1
- Battle's sign (post-mastoid ecchymosis) 1, 4
- Hemotympanum 1
- CSF otorrhea or rhinorrhea 1, 5
- Intracranial hemorrhage 1
However, these classic signs rarely co-occur—in the trauma series, other classic basilar skull fracture signs were observed in only 3-7 patients among 36 with periorbital ecchymosis. 1
Imaging Requirements
CT imaging is mandatory regardless of clinical signs. 6 The American College of Radiology recommends:
- CT orbits without contrast as the primary modality for evaluating periorbital ecchymosis after trauma, with 94.9% sensitivity for detecting fractures and associated injuries 7, 6
- CT maxillofacial for comprehensive evaluation of skull base and facial bone integrity 7, 6
- CT head when intracranial injury is suspected (68% of facial fracture patients have associated head injury) 7
The presence or absence of periorbital ecchymosis should not determine whether imaging is obtained—clinical signs alone are insufficient to rule in or rule out basilar skull fracture. 2