A 46-year-old man presents to the emergency department with new-onset drooping of his right eyelid and unequal pupils for the past two hours. He reports right-sided neck pain that began suddenly while lifting a heavy object earlier in the day. Past medical history is negative, and he does not take any medications. Vital signs are within normal limits. Physical examination reveals mild ptosis of the right eye, miosis of the right pupil, and decreased sweating on the right side of the face. Extraocular movements are intact, and there is no facial muscle weakness.
Which of the following is the most likely underlying cause of this patient’s symptoms?
The correct answer is:
A) Carotid artery dissection
Horner syndrome is caused by disruption of the sympathetic pathway to the eye and is characterized by the classic triad of ptosis, miosis, and anhidrosis. Acute onset of painful Horner syndrome, particularly with neck pain, is highly suggestive of internal carotid artery dissection, which damages postganglionic sympathetic fibers traveling along the carotid artery.
Answer choice B: Compression of the oculomotor nerve, is incorrect. Oculomotor nerve palsy causes ptosis and diplopia with a “down and out” eye position and typically results in mydriasis, not miosis.
Answer choice C: Ischemic stroke involving the pons, is incorrect. Pontine strokes can cause facial weakness and gaze abnormalities but are less likely to cause isolated Horner syndrome with neck pain.
Answer choice D: Lesion of the facial nerve, is incorrect. Facial nerve lesions cause facial muscle weakness and impaired lacrimation or taste, not pupillary abnormalities or ptosis.
Answer choice E: Tumor of the pituitary gland, is incorrect. Pituitary tumors typically cause visual field defects, such as bitemporal hemianopsia, due to optic chiasm compression rather than Horner syndrome.
Key Learning Point
Horner syndrome presents with ptosis, miosis, and anhidrosis due to disruption of the sympathetic pathway. Acute painful onset should prompt concern for carotid artery dissection.
