Approach to patient with diplopia.

This article presents an overview of the most important points a neurologist must remember when dealing with a patient complaining of diplopia. Patients with monocular diplopia and those with full ocular motility and comitant misalignment should be referred to an ophthalmologist and do not require further testing. Patients with recent onset of binocular diplopia who have associated "brainstem" symptoms should have an urgent brain MRI. All patients with 3rd cranial nerve palsy require urgent brain CTA to rule out compressive aneurysmal lesion. Management of patients over 50 years of age with microvascular risk factors with new onset of 6th nerve palsy is controversial: some image these patients at presentation while others choose a short period of observation as most of these patients would have a microvascular etiology for the 6th nerve palsy which should improve spontaneous in 2-3 months. All others with 6th nerve palsy require brain MRI with contrast. Patients with 4th palsy with hyperdeviation that worsens in downgaze should have an MRI with contrast and all others referred to an ophthalmologist. If there is more than one cranial nerve palsy, urgent neuroimaging should be performed with attention to cavernous sinus and superior orbital fissure. Ocular myasthenia should be suspected in patients with eye misalignment that does not fit a pattern for any cranial nerve palsy. Orbital pathology (most commonly thyroid eye disease) can result in restriction of ocular motility and has specific clinical signs associated with it.