Atypical features prompting neuroimaging in acute optic neuropathy in adults

Background: Acute optic neuropathy due to an intracranial lesion may masque rade as optic neuritis or nonarteritic anterior ischemic optic neuropathy ( NAION). We reviewed the records of patients who presented with acute unilat eral optic neuropathy that was initially diagnosed as optic neuritis or NAI ON but who ultimately proved to have an underlying structural lesion. Methods: Retrospective observational case series. We reviewed the records o f patients with the initial diagnosis of optic neuritis or NAION in whom th e diagnosis was changed to an intracranial etiology at four tertiary care n euro-ophthalmology centres between 1995 and 1998. Results: Eight cases were identified in which atypical features prompted fu rther investigation, including neuroimaging, leading to the diagnosis of an intracranial etiology for the optic neuropathy. Five patients were discove red to have neoplasms (a tuberculum sellae meningioma in two cases, an opti c nerve sheath meningioma in two cases and a metastatic lesion in one case) , and three patients had intracranial sarcoidosis. Atypical features for op tic neuritis included a progressive course, absence of pain, optic atrophy at presentation, lack of significant visual improvement and age over 40 yea rs. For NAION, the atypical features included progressive course, optic atr ophy on presentation, absence of vasculopathic risk factors and preceding t ransient visual loss. Interpretation: Clinicians should be aware that patients with intracranial lesions may present with acute optic neuropathy mimicking optic neuritis or NAION and that certain atypical features should warrant consideration for neuroimaging.