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Horner syndrome

  • Definition

    Horner syndrome is a rare condition that affects the nerves to the eye and face.

    Causes, incidence, and risk factors

    Horner syndrome can be caused by any interruption in a set of nerve fibers that start in the part of the brain called the hypothalamus and run to the face.

    Sympathetic nerve fiber injuries can result from:

    • Injury to one of the main arteries to the brain (carotid artery)
    • Injury to nerves in the neck called the brachial plexus
    • Migraine or cluster headaches
    • Stroke, tumor, or other damage to a part of the brain called the brainstem
    • Tumor in the top of the lung

    Rarely, Horner syndrome may be present at birth (congenital). The condition may occur with a lack of color (pigmentation) of the iris (colored part of the eye).