Horner's syndrome

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Horner's syndrome is a triad of features resulting from interruption of the sympathetic pathway from the hypothalamus to the orbit, as follows:

  • slight ptosis
  • pupillary miosis:
    • due to paralysis of the sympathetically innervated Muller's muscle which normally dilates the pupil
  • anhydrosis over the forehead

Last reviewed 01/2018