Horner syndrome is a rare condition that has no sex or race predilection and is characterized by the clinical triad of a miosis, anhidrosis, and small, unilateral ptosis. The prompt diagnosis and determination of the etiology of Horner syndrome are of utmost importance, as the condition can result from many life-threatening systemic complications. Horner syndrome is often asymptomatic but can have distinct, easily identified characteristics seen with an ophthalmic examination. This report describes a patient who presented with Horner syndrome resulting from an internal carotid artery dissection.
Case Presentation
A 61-year-old woman presented with periorbital pain with onset 3 days prior. The patient described the pain as 7 of 10 that had been worsening and was localized around and behind the right eye. She reported new-onset headaches on the right side over the past week with associated intermittent vision blurriness in the right eye. She had a history of mobility issues and had fallen backward about 1 week before, hitting the back of her head on the floor without direct trauma to the eye. She was symptomatic for light sensitivity, syncope, and dizziness, with reports of a recent history of transient ischemic attacks (TIAs) of unknown etiology, which had occurred in the months preceding her examination. She reported no jaw claudication, scalp tenderness, and neck or shoulder pain. She was unaware of any changes in her perspiration pattern on the right side of her face but mentioned that she had noticed her right upper eyelid drooping while looking in the mirror.
This patient had a routine eye examination 2 months before, which was remarkable for stable, nonfoveal involving adult-onset vitelliform dystrophy in the left eye and nuclear sclerotic cataracts and mild refractive error in both eyes. No iris heterochromia was noted, and her pupils were equal, round, and reactive to light. Her history was remarkable for chest pain, obesity, bipolar disorder, vertigo, transient cerebral ischemia, hypertension, hypercholesterolemia, alcohol use disorder, cocaine use disorder, and asthma. A carotid ultrasound had been performed 1 month before the onset of symptoms due to her history of TIAs, which showed no hemodynamically significant stenosis (> 50% stenosis) of either carotid artery. Her medications included oxybutynin chloride, amlodipine, acetaminophen, sertraline hydrochloride, lidocaine, albuterol, risperidone, hydroxyzine hydrochloride, lisinopril, omeprazole, once-daily baby aspirin, atorvastatin, and calcium.
At the time of presentation, an ophthalmic examination revealed no decrease in visual acuity with a best-corrected visual acuity of 20/20 in the right and left eyes. The patient’s pupil sizes were unequal, with a smaller, more miotic right pupil with a greater difference between the pupil sizes in dim illumination (Figure 1).
As the patient had pathologic miosis, conditions causing pathologic mydriasis, such as Adie tonic pupil and cranial nerve III palsy, were ruled out. The presence of an acute, slight ptosis with pathologic miosis and pain in the ipsilateral eye with no reports of exposure to miotic pharmaceutical agents and no history of trauma to the globe or orbit eliminated other differentials, leading to a diagnosis of right-sided Horner syndrome. Due to concerns of acute onset periorbital and retrobulbar pain, she was referred to the emergency department with recommendations for computed tomography angiography (CTA), magnetic resonance imaging (MRI), and magnetic resonance angiogram (MRA) of the head and neck to rule out a carotid artery dissection.