Horner syndrome
The three-neuron pathway, how associated signs localise the lesion, apraclonidine testing, and why a painful acute Horner syndrome is carotid dissection until imaging says otherwise.
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Interruption of the oculosympathetic pathway anywhere from hypothalamus to eye gives ptosis, miosis and anhidrosis on the same side.
- The signs are subtle. The question is always where is the lesion, and the associated features usually answer it.
- Acute and painful means carotid dissection until imaging shows otherwise.
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Finished reading?
Sources
- Therapeutic Guidelines: NeurologyAU/NZTherapeutic Guidelines Limited
- Australian and New Zealand Living Clinical Guidelines for Stroke ManagementAU/NZStroke Foundation, Living guideline
- Antiplatelet treatment compared with anticoagulation treatment for cervical artery dissection (CADISS)The Lancet Neurology, 2015
- Aspirin versus anticoagulation in cervical artery dissection (TREAT-CAD): an open-label, randomised, non-inferiority trialThe Lancet Neurology, 2021
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy