Frontal sinus

paranasal sinus in the frontal bone. The frontal sinus is not present at birth; it starts developing at the age of 2 years and reaches its final volume after puberty. The global morphology of the frontal sinus is very variable, with both frontal sinuses frequently being asymmetrical in size, causing displacement of the intersinus septum to one side. The pneumatization of this sinus may extend into the vertical part and/or the horizontal part of the frontal bone; extension into the orbital roof may also be present. Aplasia is seen in about 4% of the population. In addition to right and left, a central frontal sinus may be seen. The frontal sinus drains into the ostiomeatal unit via the frontal recess. Also, see frontal sinus.

2. Pathology

Inflammation

Inflammatory changes are commonly seen in the frontal sinus (see sinonasal cavities inflammation). While orbital complications are more common with ethmoid sinusitis, intracranial complications (albeit rare) more often originate from frontal sinusitis because of a rich vascular network connecting the posterior sinus mucosa with the meninges. Bone destruction due to osteomyelitis is also most often seen in the frontal sinus.

Mucocele

The frontal sinus is the most common location for a mucocele. The sinus appears radiologically as an expanded airless cavity. Apart from frontal bossing, it may cause deformity of the adjacent orbit; intracranial extension of a frontal mucocele may be seen.

Trauma

Frontal fractures are the result of a direct trauma, or extension of a calvarial fracture. A posterior wall fracture may be complicated by cerebrospinal fluid leak, a pneumocele, meningitis or contusion to the frontal brain parenchyma. Also, see facial fracture.

Tumoural pathology

The frontal sinus is the most common location for sinonasal osteoma (see osteoma sinonasal).

Primary frontal sinus carcinoma is rare. Frontal bone erosion occurs rapidly, with spread into the adjacent structures (Fig.1). The prognosis is poor. Also, see sinonasal cavities cancer.

RH