A man aged 51 years was admitted to the internal medicine service with a recent history of left-sided hemibody paresthesia, dysphagia, and ataxia. He also reported a single episode of binocular diplopia that lasted for 1 day and resolved spontaneously. Otherwise, his medical history was unremarkable.
On physical examination, there was mild right-sided ptosis and miosis. Pain and temperature sensation were not evaluated. After instilling 10% topical cocaine eyedrops, the right pupil did not change its size whereas the left pupil dilated by 2 mm, supporting a diagnosis of right-sided Horner syndrome. With the exception of delayed initiation of saccades, extraocular motility was full, and there was no nystagmus.
Najem K, Margolin EA. A Special Case of Horner Syndrome. JAMA Ophthalmol. 2016;134(10):1193-1194. doi:10.1001/jamaophthalmol.2016.1654