Anterior Cranial Fossa Fractures

Classic Clinical Signs

Because the bones of the anterior cranial fossa are intimately related to the superior orbits and the nasal cavity, fractures often present with pathognomonic external signs that can be observed at the bedside long before imaging is acquired.

• Periorbital Ecchymosis (Raccoon Eyes): Bilateral pooling of blood within the soft tissues surrounding the eyes. Blood from the fractured orbital roof directly tracks forward into the periorbital fascial planes. Unlike a direct black eye, raccoon eyes spare the posterior margins of the eyelids.
• Cerebrospinal Fluid (CSF) Rhinorrhoea: The leakage of clear cerebrospinal fluid from the nasal passage. This indicates a direct traumatic tear linking the subarachnoid space to the nasal cavity, typically occurring at the fragile cribriform plate. This creates an open pathway for ascending bacterial meningitis.
• Anosmia: Complete loss of the sense of smell. This results from traumatic shearing forces severing the delicate olfactory nerve filaments (Cranial Nerve I) as they pass vertically through the cribriform plate.

Radiographic Hallmarks

While the bony fracture line itself is the definitive proof, indirect radiological signs are often the first clue pointing to a basal skull fracture.

• Pneumocephalus: The abnormal presence of air within the cranial vault (subdural or subarachnoid spaces) seen on CT. Air universally implies a breach connecting the sterile intracranial space with an air-containing cavity (such as the paranasal sinuses or the mastoid air cells).
• Sinus Opacification: An air-fluid level or total opacification within the frontal, ethmoid, or sphenoid sinuses secondary to acute hemorrhage (hemosinus).