A Case with Bilateral Dural Arteriovenous Fistulae Manifesting as Sequential Trochlear, Oculomotor Nerve Palsies

Purpose: We report a patient with bilateral dural arteriovenous fistulae (DAVF) who initially presented with unilateral, isolated trochlear nerve palsy; and later with contralateral, oculomotor nerve palsy.Case summary: A 72-year-old male without any underlying disease or a trauma history visited with sudden vertical diplopia in both eyes that had developed 5 days prior. Brain magnetic resonance imaging (MRI) performed before his first visit was unremarkable. The eye movement test revealed hyperdeviation and limitation of downgaze in the left eye; we thus suspected unilateral, ischemic trochlear nerve palsy and this was indeed observed. However, the diplopia did not improve and limitations of the upper, medial gaze of the right eye developed after 3 months. Follow-up examinations (orbital computed tomography, brain MRI, and cerebral angiography) revealed bilateral DAVF running from the left to the right. He underwent gamma-knife radiosurgery; then the eye movement limitations and diplopia improved.Conclusions: Diplopia manifesting as paralysis in an elderly patient may be caused by DAVF; the diplopia may not always be the common ischemic paralytic strabismus. DAVF should be considered during differential diagnosis and further radiological examinations may be needed.