An 80 year old gentleman presented with bilateral, sequential ischaemic optic neuropathy. He initially developed progressive loss of vision in left eye with loss of colour vision and subsequently developed similar symptoms in the right eye with headaches, weight loss, malaise and lethargy. His visual acuity dropped to 6/12 on the right and counting fingers on the left. He had a dense central scotoma in left eye with left-sided RAPD but no other focal neurological deficits.
Blood tests revealed an ESR of 107 with an MPO ANCA titre of 19. MRI brain with contrast showed prominent meningeal enhancement and infiltration with ischaemic changes in the brain. CSF analysis revealed WCC of 24 (95% lymphocytes), RCC 22 and protein 0.4 g/L with negative bacterial culture. Temporal artery biopsy was normal.
He was treated initially with IV methylprednisolone and 6 cycles of IV cyclophosphamide and subsequently put on methotrexate. His systemic symptoms have resolved completely and his visual acuity continues to gradually improve.
MPO-ANCA vasculitis can mimic temporal arteritis and should be considered in patients presenting with an ischaemic optic neuropathy. It is also a treatable cause of meningeal disease.