Paranasal sinus fractures

Paranasal sinuses are air-filled cavities surrounding the nasal cavity proper which includes maxillary sinus, sphenoid sinus, frontal sinus and ethmoid sinus. Trauma to the superior and middle thirds of the face can often lead to in paranasal sinus fractures involving one or more paranasal sinuses. Furthermore, forces greater than paranasal sinus resistance may result in traumatic brain injury.

Epidemiology

Males in their 20-30s are the most common group to sustain facial trauma . The etiology for facial trauma causing paranasal fractures varies geographically. In urban regions, assaults and motor vehicle accidents are the main reasons for facial trauma. By contrast, in rural regions, animal-related accidents are the main cause of facial trauma .

Clinical presentation

Presenting complaint is usually facial pain and in some instances deformity although facial swelling can make the assessment of sinus wall depression difficult. Specific clinical signs unique to sinuses are discussed below. Often other injuries (e.g. upper limb, cranial and thoracic) are present that may be more clinically impressive. As such imaging with CT is often the first time a paranasal sinus fracture is suspected .

Anatomy and pathology

Traumatic forces directed at the facial skeleton is transmitted and absorbed by a framework of facial bones that surround paranasal sinuses. Disruption to the bony framework results in paranasal sinus fractures. The Le Fort classification system categorizes common types of bony framework disruption along "lines of weakness" and can be associated with certain types of paranasal sinus fractures. In addition to Le Fort classification system, other classifications have been devised for facial fractures that are too complex for the Le Fort fracture lines which focus on anatomical subunits of the mid-face including zygomaticomaxillary complex (ZMC), the naso-orbitoethmoidal complex (NOE), and the dentoalveolar complex (DAC).

• Le Fort I and II fractures, ZMC fractures: associated with maxillary sinus fracture (most common paranasal sinus fracture)  
• Le Fort II and III fractures: associated with ethmoid sinus fracture
• NOE fractures: associated with frontal/ethmoid sinus fracture 

Maxillary sinus fracture

Maxillary sinus fractures can occur in isolation from a direct blow, or as part of a more extensive injury such as Le Fort fractures.

• the commonest mechanism of injury
  •  high-energy trauma to the eyeball
• common injuries and fracture sites
  • blow-out fracture: floor of orbit/roof of sinus  
  • iatrogenic injury (e.g. displaced dental implant) - inferior sinus wall 
• specific symptoms
  •  hypoesthesia of upper lip/dental arch, diplopia  
• complications
  • oroantral fistulae, maxillary sinus infection 

Frontal sinus fracture

Frontal sinus fractures are relatively uncommon, usually seen in the setting of other facial fractures.

• commonest mechanism of injury
  • motor vehicle accident
• common fracture sites 
  • anterior sinus wall
  • posterior sinus wall 
• red flag symptoms
  •  fever, clear nasal discharge, altered conscious state  
• complications
  • dural tear, CSF rhinorrhea, mucocele,and intracranial infection (e.g. meningoencephalitis)

Ethmoidal sinus fracture 

Ethmoidal sinus fractures are usually seen in the setting of nasal fractures (naso-orbitoethmoid complex fractures).

• commonest mechanism of injury
  •  motor vehicle accident
• common fracture site
  •  superior sinus wall (cribriform plate)
• isolated injury rare, usually associated with injury to NOE complex and frontal sinus
• specific symptoms
  • hyposmia, anosmia
• complications
  • olfactory nerve damage, dacryocystitis, CSF rhinorrhea, and intracranial infection

Sphenoidal sinus fracture

Transsphenoidal fractures are usually seen in the setting of more extensive base of skull fractures, often extending to involve anterior cranial fossa or petrous temporal bones.

• mechanism of injury
  • various 
• isolated injury rare, usually associated with complex craniofacial injuries 
• specific symptoms
  • clear nasal discharge, visual disturbance  
• complications
  • optic/oculomotor nerve damage, internal carotid artery damage, CSF rhinorrhea

Radiographic features 

A plain radiograph may be used to assess a number of structures but CT scans are now the gold standard in diagnosis and surgical planning of facial trauma.

Plain radiograph

• Waters projection for assessment of maxillary bone/sinus, orbit, zygomatic arch 
• Caldwell projection for assessment of frontal and ethmoid sinuses, orbit, frontozygomatic sutures 

CT

• blood in sinus (hemosinus)  
• dislocated bone fragments
• gas in soft tissues 
• pneumocephalus: associated with ethmoidal/sphenoidal sinus fractures 

Treatment and prognosis

Treatment is dictated by the complexity of facial fracture, sinus wall location and associated injuries. Conservative management can be an option for maxillary, frontal and ethmoid sinus fractures. For example, anterior wall of the frontal sinus is usually managed conservatively, by contrast, posterior wall of frontal sinus require surgery due to potential extension into intracranial space. Sphenoidal sinus fracture always requires surgery due to the presence of neurovascular structures in the sinus. There is a lack of evidence for antibiotic prophylaxis in patients with basal skull fractures involving the paranasal sinuses .