Carotid dissection in Horner syndrome

A 68-year-old gentleman was referred to the emergency eye clinic from the general emergency department to rule out giant cell arteritis due to a headache history. This gentleman reported constant holocranial headaches for the past 2 months. He had no other giant cell arteritis symptoms and his serology including platelet count, erythrocyte sedimentation rate, and C-reactive protein were all within normal limits. He had no other relevant history including neck manipulation. When he was seen in the emergency eye clinic, a neuroophthalmic examination was performed and it showed the presence of a left 1 mm ptosis and anisocoria that worsened in the dark with a left miotic pupil. Both pupils constricted normally to light but the left pupil dilated relatively slowly when light was withdrawn (“positive dilation lag”) and tested positive with topical apraclonidine 0.5% drops showing reversal of the anisocoria, confirming a diagnosis of left Horner syndrome. He himself did not notice the ptosis nor did anyone around him, including previous physicians. Due to the presence of headache and a Horner syndrome, it was deemed that this was a “painful Horner” scenario, which is a carotid dissection until proven otherwise. This patient was sent for urgent imaging, and because he declined a CT angiogram, an MRI/MR angiography was done and it showed a left internal carotid artery dissection. (Contributed by Dr. Danah Albreiki.)