Horner's Syndrome after Carotid Endarterectomy: A Case Report and Review of Literature.

Horner's syndrome, characterized by ptosis, miosis, and anhidrosis, results from oculosympathetic complex injury, often due to trauma affecting the superior cervical ganglion. Although rare following carotid surgery, we present a case of Horner's syndrome after elective carotid endarterectomy (CEA). This report explores potential mechanism, including prolonged surgical retraction and hematoma formation, while reviewing similar cases in the literature. A 45-year-old woman presented with recurrent dizziness and progressive left-sided hearing impairment over 5 years. She also reported neck discomfort and experienced five episodes of amaurosis fugax in her left eye within 1 week. Computed tomography revealed occlusion of the right common and internal carotid artery (ICA), along with a 90% stenosis at the left common carotid bifurcation extending into the left ICA. Subsequently, an elective left CEA was performed. Within 24 hours postoperatively, she developed clinical signs of Horner's syndrome, including left-sided ptosis, miosis, anhidrosis, and concurrent facial nerve palsy. Notably, there was no evidence of hematoma formation or sensorimotor deficits. This case highlights the rare occurrence of Horner's syndrome as a postoperative complication of CEA. Surgeons should be mindful of anatomical variations and potential intraoperative mechanisms contributing to this complication to enhance prevention strategies. Recognizing this risk is essential for optimizing postoperative care and patient counseling.