General Medical Information

Considerations For Endoscopic Sinus Surgery

Barbara A. Zeifer

A patient with repetitive acute sinusitis or chronic sinus inflammation that is incompletely eradicated after medical treatment poses a distinct clinical problem to the otolaryngologist. This patient may be a candidate for functional transnasal endoscopic sinus surgery, now a popular and widely accepted procedure. Patient selection for this procedure entails a detailed clinical history, systematic nasal endoscopy, and direct coronal CT. Interpretation of the CT scan must be tailored to the needs of the surgeon. The focus is not so much on providing a list of anatomic regions where mucosal disease is present but on delineating specific anatomic features and identifying patterns of disease that suggest functional obstruction of central drainage pathways. The ostiomeatal complex, the sphenoethmoid recess, and the frontal recess become the prime areas of interest. Complete or partial obstruction of these outlets causes inflammatory changes in the associated sinus cavities. This obstruction often is caused by a combination of congenital distortion and superimposed disease. It is the combination of these processes that CT should define. The anatomic relations of the sinuses and nose are well seen on coronal CT scans. The structures of the ostiomeatal complex are best evaluated in this plane. The anatomic features of the frontal recess and sphenoethmoidal recess are best evaluated by means of sagittal reformation of thin axial images.

Many anatomic variations of the nose and paranasal sinuses can interfere with sinus drainage and thus predispose a patient to sinusitis. Others alter expected anatomic norms, potentially complicating a surgical procedure. Most of these variations can be identified on coronal CT scans. They include the concha bullosa cell, septal deviation and spur, lateral convexity of the middle turbinate, pneumatization and inversion of the uncinate plate, prominent agger nasi cell, prominent ethmoidal bulla, and Haller cell. The anterior attachment of the uncinate plate can be visualized: its configuration affects the surgical approach to the frontal recess. Anomalies of the frontal recess include large agger nasi and frontal bulla cells. Anomalies of the posterior ethmoidal sinus include pneumatization of the palatine bone and extension of the ethmoid into the sphenoid bone, producing an Onodi cell. Potential hazards can be identified preoperatively, such as exposed optic nerves within the sphenoidal sinus, bony defects of the parasphenoidal carotid canal, hypoplasia or aplasia of the maxillary antrum, and antral septation.