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Diseases of the Paranasal Sinuses: Overview |  |
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The maxillary sinus is the largest paranasal sinus and is divided by a thin septum into caudal and rostral parts. The frontal sinus has a large communication with the dorsal conchal sinus at its rostral end, thereby forming the conchofrontal sinus. The conchae or turbinates are delicate scrolls of bone that are attached laterally in the nasal passage and contain the conchal sinuses. The caudal and rostral maxillary sinuses have separate openings
into the middle nasal meatus, and the caudal maxillary sinus communicates with the frontal sinus through the large frontomaxillary opening. Diseases that originate in one sinus cavity may extend to and involve others. |
| Most diseases of the paranasal sinuses cause mucopurulent or bloody nasal discharge. Drainage is unilateral, in contrast to disease of the lungs, pharynx, and guttural pouches, because the source of discharge is rostral to the caudal border of the nasal septum. Unilateral facial swelling, epiphora, dull percussion of the sinuses, and inspiratory noise are common manifestations of disorders of the sinuses. |
| On endoscopy, purulent material, a mass, or blood can be seen in the nasal passage originating from the nasomaxillary opening. Lateral and dorsoventral radiographs of the skull may reveal fluid lines, sinus cysts, solid masses, or lytic/proliferative changes associated with dental disease and neoplasia. Oblique projections in a dorsal to ventral direction may be required to improve views of the tooth roots. Computed tomography is useful, particularly for ventral conchal sinus
disease. Centesis of the maxillary or frontal sinuses is performed to obtain fluid for bacterial culture, sensitivity testing, and cytologic examination. With sedation and local anesthesia, the sinuses can be examined in the standing horse by insertion of an arthroscope (4.0 mm). A second portal could be used to insert an instrument into the sinus to obtain specimens, debride tissue, and lavage the sinus cavity. |
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