An otherwise healthy man in his 30s presented to an optometrist with sudden onset horizontal diplopia and blurry vision. Symptoms increased in severity as his gaze turned to the left. Physical examination was notable for left sixth cranial nerve palsy. The remainder of the neurologic examination was normal. The optometrist ordered a magnetic resonance imaging (MRI) scan of the brain with and without contrast that revealed asymmetric left-sided enhancement of the dura in the region of Dorello’s canal (Figure). The differential diagnosis remained broad and a lumbar puncture was recommended by the neuroradiologist to evaluate for a dural-based process such as neurosarcoidosis.
Agarwal A, Eisenberg A, Woods SK. A Common Cause of Cranial Nerve VI Palsy—Hidden in Plain SightA Teachable Moment. JAMA Intern Med. 2016;176(8):1066-1067. doi:10.1001/jamainternmed.2016.2661