Intermittent mydriasis associated with carotid vascular occlusion.

Area of Science:

• Ophthalmology
• Neurology
• Vascular Medicine

Background:

• Benign episodic unilateral mydriasis (BEUM) is typically seen in young women with a history of migraines.
• The exact cause of BEUM remains unclear, but autonomic nervous system dysfunction is suspected.

Observation:

• Two patients presented with stereotyped, intermittent, neurologically isolated, unilateral mydriasis.
• Case 1: A 78-year-old male with 100% left internal carotid artery (ICA) occlusion due to atherosclerosis.
• Case 2: A 26-year-old female with migraine history developed mydriasis after chest trauma, revealing ipsilateral ICA dissection and 65% occlusion.

Findings:

• Neither patient experienced permanent anisocoria.
• These are the first reported cases of episodic unilateral mydriasis associated with ICA occlusive disease in the ophthalmic literature.
• The intermittent mydriatic episodes are hypothesized to result from transient autonomic nervous system dysfunction secondary to ICA disease.

Implications:

• Consider imaging of the internal carotid artery (ICA) in patients presenting with atypical features of BEUM.
• Atypical features include older age, male gender, non-isolated mydriasis, or recent trauma.
• This finding broadens the differential diagnosis for episodic unilateral mydriasis.