Monarch Disease Ontology identifier MONDO_0001123 (chronic sphenoidal sinusitis) is inflammation of the sphenoid sinus that typically lasts beyond eight weeks. It is caused by infections, allergies, and the presence of sinus polyps or a deviated septum. Signs and symptoms include headache, nasal discharge, swelling in the face, dizziness, and breathing difficulties. Also known as: chronic sphenoid sinusitis, sphenoid sinusitis, chronic, sphenoidal sinus-chr..