Abstract

A 52 year-old male diabetic, hypertensive and dyslip¬idemia presented with diplopia and dizziness for one day. He denied any weakness, clumsiness, nausea, vom¬iting, photophobia, fever or chills. Ocular exam showed a disconjugate gaze at rest, weakness of the right me¬dial rectus muscle, impaired convergence test, and bilateral 3-mm reactive pupils. The diplopia resolved by closing either eye. The remaining extraocular muscles and other cranial nerves were normal. There was no nystagmus, ptosis, or visual field deficit. MRI of the brain revealed a tiny focus of restricted diffusion in the right posteri¬or lateral midbrain.
Isolated extra ocu¬lar palsy is usually thought to be caused by orbital lesions or muscular diseases. Here, we report a rare case of midbrain infarction involving the lateral subnucleus of the oculomotor nuclear complex resulting in isolated medial rectus palsy and presenting as diplopia, with no other stroke manifestations.