Is sphenoid sinus opacity significant in patients with optic neuritis?

Optic neuritis secondary to sinus disease is an infrequent but well-documented association. When a patient presents with signs of optic nerve dysfunction and orbital inflammation the significance of widespread sinus disease on radiology is clear and the management is straightforward. We present a group of patients with isolated optic neuritis and radiological evidence of spheno-ethmoiditis and discuss the clinical relevance of this finding.

We reviewed the notes of 11 patients with optic neuritis who, because of atypical headache, underwent neuroimaging revealing sphenoid sinus opacity. Six patients had endoscopic drainage of the sphenoid sinus; 4 were treated medically.

Sinus contents included fungal infection (2), mucopurulent material (5), polyps (1) and necrotic tumour (1). Narrowing of the optic canal due to chronic osteomyelitis was found in 1 patient with irreversible optic atrophy. Visual loss was reversible in 6 patients. Four patients had normal radiological findings after treatment. Two patients had recurrent optic neuritis with sphenoid sinusitis on MRI scan, resolving on treatment, during the 4 year follow-up period.

Possible mechanisms of nerve damage in this situation include direct spread of infection, occlusive vasculitis and bony deficiency in the wall of the sinus. Patients presenting with isolated optic neuritis and atypical headache should be scanned; an opaque sphenoid sinus in the context of visual loss should not be dismissed as coincidental but assumed to be pathological and the patient referred for drainage. Sphenoid sinusitis is an uncommon but treatable cause of optic neuritis.