The submucosa tends to be thickened, fibrotic and infiltrated with chronic inflammatory cells and the mucosa tends to encyst, thins to a single cuboidal layer and is heaped up. There are large areas of mucosa devoid of cilia and there is a tendency for the cysts to expand and secrete fluid into their lumens. These cysts can erode bone by pressure or enzymatic digestion and they are prone to infection. Mucocele formation may result from injury to mucosa, fracture of the frontonasal duct or mismanagement of a frontal sinus injury. Due to the high force required to cause frontal sinus fractures there is a high incidence of associated injuries therefore all patients need a thorough evaluation on presentation.
Initial evaluation is directed toward management of the airway, circulation and other organ systems.
All patients need ophthalmologic and neurologic examinations and the cervical spine should be cleared radiographically in all cases. Once the patient has been stabilized evaluation of the frontal sinus injury should proceed with computerized tomography because it clearly depicts fractures, the amount of depression, the contents of the sinus cavity and adjacent brain and overlying soft tissue. Historically the first operation for fracture of the frontal sinus was described by Reidel in 1898 and involved ablation of the frontal sinus allowing the skin of the forehead to rest against the posterior wall of the sinus or against the dura. Killian in 1904 performed a similar operation but left a 10mm rim of supraorbital bone for cosmesis. In 1921 Lynch devised the external frontoethmoidectomy in an attempt to improve aesthetics.