The ethmoidal sinus is a complex structure, with the horizontal plate and the roof forming part of the anterior cranial fossa floor. Due to the thin bone composition and its close connection to the dura mater, fractures of the ethmoidal sinus are often associated with cerebrospinal fluid leakage. The posterior ethmoidal sinus is adjacent to the optic canal, making the optic nerve susceptible to injury in cases of trauma. If the fracture involves the arteries (such as the anterior or posterior ethmoidal arteries) within the ethmoidal sinus, epistaxis or retrobulbar hematoma becomes unavoidable.
Clinical Manifestations
Ethmoidal sinus fractures are commonly accompanied by skull injuries, such as nasoethmoidal-orbital complex fractures, and present with complex clinical findings. Mild ethmoidal sinus fractures may exhibit no significant clinical symptoms. When a nasal bone fracture is present, a depressed nasal bridge may occur, with a flattened and widened nasal root. Intercanthal spacing exceeding 40 mm (compared to the normal range of 34–37 mm) may also be observed. Orbital involvement may result in periorbital ecchymosis or emphysema, subconjunctival hemorrhage, intraorbital hematoma, proptosis or enophthalmos, diplopia, and lacrimation. Fractures involving the roof of the ethmoidal sinus may lead to cerebrospinal fluid rhinorrhea and olfactory impairment. In cases where the sphenoid sinus and optic nerve canal are affected, a Marcus-Gunn pupil, severe visual impairment, or even blindness may be observed.
Diagnosis
A significant decline in vision on the affected side following trauma, accompanied by a Marcus-Gunn pupil, should raise suspicion for an optic canal fracture. Blurring of the margins around the optic foramen on Rhese view X-rays also suggests the possibility of a fracture. Axial CT imaging aids in confirming the location of an optic canal fracture and identifying associated orbital injuries.
Treatment
Treatment varies according to the clinical presentation. For isolated ethmoidal sinus fractures without significant symptoms, conservative management may be sufficient. Patients with accompanying periorbital fractures but without diplopia or globe displacement may also initially be managed conservatively. In cases where orbital symptoms are present, early surgical intervention is required to reposition displaced orbital contents, reduce fracture fragments, and reconstruct the orbital walls.
The optimal timing for surgical repair is typically 7–10 days after injury. For vision loss caused by an optic canal fracture, optic canal decompression should be performed. Indications for the procedure include post-traumatic vision impairment with CT evidence of an optic canal fracture, warranting timely endoscopic decompression. If an optic canal fracture is not detected and steroid treatment for over 12 hours does not result in vision improvement, consideration may be given to the following surgical options:
- Transnasal exploration of the ethmoidal and sphenoid sinuses with optic canal decompression.
- Transorbital approach for optic canal decompression. This involves first performing an external ethmoidectomy, followed by dissection of the medial orbital wall to expose the anterior and posterior ethmoidal arteries. Separating these arteries along their trajectory 4.5–5.0 cm behind the medial canthus reveals the medial ridge of the optic canal. In surgical microscopy, bone fragments are removed, with the medial wall of the optic canal being resected as extensively as possible.