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Carotid Dissection – Horner Syndrome Mechanism — SCE Neurology MCQ

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ModerateCerebrovascular DiseaseCarotid Dissection – Horner Syndrome MechanismSCE Neurology

A 38-year-old woman presents with sudden onset of a painful right Horner syndrome. She has right neck and facial pain. There is no weakness or sensory loss. MRI angiography shows a right internal carotid artery dissection with intramural haematoma and no intracranial extension. What does the Horner syndrome indicate in this context?

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Correct answer: A — Disruption of sympathetic fibres running along the internal carotid artery by the dissection

In carotid artery dissection, a painful ipsilateral Horner syndrome occurs because the post-ganglionic sympathetic fibres ascend along the wall of the internal carotid artery and are damaged by the intramural haematoma of the dissection. The Horner syndrome is partial (miosis and ptosis only, without anhidrosis of the forehead — because facial sweating fibres travel with the external carotid artery). A: Brainstem Horner syndrome has additional signs. C: Cavernous sinus would have multiple cranial nerve palsies. D: Pancoast tumour causes a pre-ganglionic Horner. E: Cervical cord lesion causes a central Horner with other signs.

Reference: RCP National Clinical Guideline for Stroke (2023); Clinical Neuroanatomy