Horner Syndrome



Unilateral sympathetic denervation of the eye produces signs of Horner syndrome:
  • Relaxation of retracting muscles in upper and lower lids:
    • Ptosis (drooping of the lids)
  • Loss of pupillary dilator innervation:
    • Miosis (unopposed pupillary constriction)
  • Loss of sympathetic stimulation of sweat glands:
    • Anhidrosis (unilateral lack of swelling, difficult to appreciate and may be absent)


  • 40% unknown (in 1 large series)
  • Tumors of lung or metastases to cervical nodes:
    • May interrupt preganglionic sympathetic fibers (between thoracic sympathetic trunk and superior cervical ganglion)
  • Trauma: Penetrating neck wounds directly injure sympathetic fibers
  • Pneumothorax:
    • Tension pneumothorax may cause traction on sympathetic fibers owing to shift of mediastinal structures
  • Infiltration or infection of cervical nodes:
    • Sarcoidosis, tuberculosis
  • Vascular disorders:
    • Migraine or cluster headaches
    • Carotid artery dissection
  • Lateral medullary infarction produces Horner syndrome as part of the Wallenberg syndrome:
    • Presents with vertigo and ataxia, which may overshadow the Horner syndrome
  • Cavernous sinus thrombosis may present with some of the features of Horner syndrome:
    • The condition typically causes headache or eye pain
    • Ocular signs include ocular palsies, pain, chemosis, and proptosis

Pediatric Considerations
  • Hereditary Horner syndrome:
    • Blue iris (or irregular coloration) on affected side
    • Brown on unaffected side (heterochromia iridis)
  • Birth trauma:
    • May cause damage to sympathetic chain
  • New Horner syndrome in a child should prompt workup for tumor (neuroblastoma)

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