The frontal sinus is located in the middle of the supraorbital region, adjacent to important structures such as the skull and orbit. Frontal sinus fractures can occur when this area is struck by an external force. Frontal sinus fracture injuries vary in severity, from affecting the appearance in mild cases to affecting the skull and brain in severe cases and even causing fatal damage.
Surgical anatomy
The frontal sinus is located between the inner and outer bony plates behind the brow arch of the frontal bone and above the septal sinus, one on each side, and the left and right frontal sinuses are mostly asymmetrical. The frontal sinus consists of four walls: the anterior wall, the outer plate of the frontal bone, is the thickest; the posterior wall, the inner plate of the frontal bone, is thinner; the bottom wall, the supraorbital wall, is the thinnest; and the medial wall is the bony septum of the frontal sinus. The frontal sinus opens in the middle nasal canal through the frontal nasal canal. The bony structures adjacent to the frontal bone include the lacrimal and sieve bones below, the pterygoid bone inferiorly and posteriorly, the parietal bone posteriorly and superiorly, the zygomatic bone laterally, the nasal bone anteriorly, and the maxillary bone anteriorly and inferiorly, with the septal sinus airspace and nasal structures located below it. The frontal sinus begins to develop pneumatization from the second year of life and approaches the size of the adult frontal sinus by about 15 years of age. Therefore, frontal sinus fractures are rare in children and adolescents and occur more often in adults, especially young adults.
Fracture classification
The classification of frontal sinus fractures must take into account the status of the anterior and posterior walls of the frontal sinus and the nasofrontal canal after the injury, as well as the presence of concurrent intracranial and maxillofacial injuries. A simple and effective classification of frontal sinus fractures is that the classification can be used to infer the possible complications of the fracture and the corresponding treatment.
Causes of fractures
Most frontal sinus fractures are high velocity impact injuries and the main cause of injury is motor vehicle traffic accidents.
Fracture diagnosis
Initial examination items include: the condition of the whole body injury, cranial, vision, eye and retinal injuries, and prompt consultation with neurosurgeons and ophthalmologists if cranial and eye injuries are suspected.
1. Medical history
Ask the patient or other witnesses to understand the nature, size and direction of the injurious force, and whether there is a history of post-injury coma. Patients often have a history of coma and retrograde amnesia, and most of them have a history of long-term neurosurgical hospitalization, so old fractures are more common among the cases seen.
2. Clinical manifestations
(1) Local soft tissues may be lacerated, forehead depression deformity, and numbness in the supraorbital nerve distribution area.
(2) Frontal sinus fracture can be combined with cranial trauma such as dural tear, epidural hematoma, subdural hematoma, subarachnoid hemorrhage, cerebral contusion, anterior cranial recess fracture and cerebrospinal fluid leakage.
(3) Frontal sinus fracture can be combined with orbital wall fracture and eye injury, and the common injury manifestations include eye entropion, diplopia, lacrimation, limitation of movement, vision loss or even loss of vision.
(4) Most frontal sinus fractures are combined with fractures of other parts of the maxillofacial area, mostly concentrated in the nasal orbital sieve, orbit, zygoma and maxillary region.
3.Imaging examination
(1) Plain radiographs of Fahrenheit and lateral cephalometric films have some value in the diagnosis of frontal sinus fracture. Indirect signs such as air-fluid planes, cloudy sinus cavity or air cranium in the sinus cavity can suggest the presence of frontal sinus fracture.
(2) CT has obvious advantages over plain film for the diagnosis of frontal sinus fracture. Axial and coronal CT can clearly show the damage to the anterior and posterior walls of the frontal sinus, confirm whether there is damage to the nasofrontal canal throughout its travel, and also clarify the damage to other parts of the skull, face and orbit, and guide the development of surgical plans.
(3) MRI has no practical value in diagnosing acute frontal sinus fracture, but it can show well for distant complications such as mucous cysts.
Fracture treatment
At present, there are four main treatment options for frontal sinus fracture: (1) fracture of the anterior wall of the frontal sinus with insignificant displacement and unobstructed frontal sinus drainage, which can be treated conservatively; (2) fracture of the anterior wall of the frontal sinus with depression affecting the shape and unobstructed nasofrontal canal drainage, with fracture repositioning and fixation and reconstruction of frontal sinus anatomy; (3) fracture of the anterior wall of the frontal sinus with nasofrontal canal obstruction and intact posterior wall, with frontal sinus mucosal scratching, frontal sinus tamponade and nasofrontal canal closure. (4) posterior wall comminuted fracture, nasofrontal canal obstruction, and cranialization of the posterior wall frontal sinus. The nasofrontal canal injury and posterior wall fracture are the key factors in deciding the surgical plan.
Postoperative considerations
Postoperative saline rinses of the nasal cavity can reduce the symptoms of sinusitis and also prevent crusting of the nasolacrimal duct, maxillary sinus opening, and nasofrontal duct. Postoperative decongestants (e.g., pseudoephedrine or oxymetazoline hydrochloride) may also be used postoperatively and should be limited to 3 days. A comprehensive consideration of the extent of soft tissue injury, wound contamination, the presence of concomitant cerebrospinal fluid leakage, and other injuries selects the postoperative use of antibiotics for about 3 days. If foreign body contamination is present, treatment should continue for one week. Postoperative CT is reviewed to observe fracture repositioning. Review 3 months after surgery to observe the presence of inflammation in the frontal sinus and the patency of the nasofrontal canal.