Frontal Sinus Fractures

Excerpt

Skull fractures are common injuries observed in the setting of both blunt and penetrating trauma. The frontal sinuses are located within the frontal bone, superior and medial to the orbits. The frontal sinuses begin developing around 5 to 6 years of age and become fully developed between the ages of 12 and 20. Sensation is provided by both the supraorbital and supratrochlear nerves, which are branches of the ophthalmic division of the trigeminal nerve (CN V1). The blood supply to the frontal sinuses comes from the supraorbital and supratrochlear arteries. The frontal sinuses consist of bony anterior and posterior tables (walls) and they drain inferiorly, medially, and posteriorly via the frontal recess into either the middle meatus or ethmoid infundibulum, depending on the attachment of the uncinate process of the ethmoid bone. If the uncinate process attaches to the lamina papyracea, the frontal sinus drains into the middle meatus via the semilunar hiatus. If the uncinate process attaches to the skull base or the middle turbinate, the frontal sinus drains into the ethmoid infundibulum before emptying into the middle meatus. The anterior border of the frontal recess is the posterior wall of the agger nasi air cell, while the posterior wall is formed by the ethmoid bulla. The medial wall of the frontal recess is the middle turbinate, and the lateral wall is the orbit. While the volume of the frontal sinus is extremely variable, the average size is approximately 10 mL; the sinus itself may be entirely absent in 0.8-7.4% of patients, unilaterally, and may be bilaterally absent in up to 5% of patients.

Frontal cranial bones have a greater thickness than the more lateral temporal bones (6.15 cm in males, 7.13 cm in females compared to 4.33 cm and 4.41 cm, respectively). As a result, these fractures require a more forceful mechanism of injury than other facial bone fractures, occur less frequently than other forms of skull trauma, and often present with concurrent injuries. These other injuries include naso-orbito-ethmoid fractures, orbital injuries, cerebrospinal fluid (CSF) leak, intracranial hemorrhage, and cervical spine fractures, among others. The potential for other potentially devastating injuries to occur along with frontal sinus fractures makes a thorough evaluation of these patients imperative. Additionally, appropriate classification and indications for surgical repair of frontal sinus fractures remain controversial, resulting in a variety of management strategies.