Isolated fascicular oculomotor nerve palsy as the initial presentation of the antiphospholipid syndrome.

This case report describes a 24-year-old female who presented with sudden onset of painless diplopia and ptosis in her left eye. Examination identified an isolated incomplete pupil-sparing left oculomotor nerve palsy. Magnetic resonance imaging demonstrated focal hyperintensity in the left midbrain with infarction suggested by diffusion-weighted imaging. A diagnosis of primary antiphospholipid syndrome was made with the demonstration of a positive lupus anticoagulant. Other autoimmune markers were present on initial assessment, but did not fulfil diagnostic criteria for systemic lupus erythematosus. Anticoagulation with warfarin was commenced, with gradual resolution of neurological deficits. This case illustrates an unusual initial manifestation of primary antiphospholipid syndrome causing midbrain stroke in a young woman.