Acute optic neuritis: association with paranasal sinus inflammatory changes on magnetic resonance imaging

The authors compared the frequency of paranasal sinus inflammatory changes (SIC) on brain magnetic resonance imaging (MRI) obtained from 23 patients with new onset acute optic neuritis (ON) and 48 control patients who underwent outpatient MRI of the brain for reasons other than ON. The authors found a higher frequency of paranasal SIC in patients with ON (83%) than in controls (54%) (p = 0.02). The distribution of paranasal SIC (in ON and in controls) was maxillary (83% and 52%), ethmoid (4% and 2%), frontal (9% and 14%), and sphenoid (4% and 10%). Frequency of the maxillary SIC was significantly higher (p = 0.02) in patients with ON than in controls. Further evaluation of maxillary paranasal SIC with a grading system showed the presence of thickened mucosal lining of the sinuses (grade I) in 17% (ON) and 23% (controls), mucous retention cysts within the sinuses (grade II) in 48% (ON) and 25% (controls), and severe mucosal thickening with complete or near-complete filling of the sinus or an air-fluid level within the sinus (grade III) in 17% (ON) and 4% (controls). Combined frequency of grade II and grade III SIC was significantly higher in the ON group than in controls (p = 0.005), as was the frequency of grade III SIC alone (p = 0.02). Grade I SIC did not significantly differ between the groups. There was a trend (p = 0.09) toward a higher prevalence of bilateral sinus inflammatory changes in patients with bilateral ON. These findings suggest that ON may be associated with sinus inflammatory changes.