What is the definition of Horner Syndrome?

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

What are the alternative names for Horner Syndrome?

Oculosympathetic paresis

What are the causes for Horner Syndrome?

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 travel to the face and eyes. These nerve fibers are involved with sweating, the pupils in your eyes, and the upper and lower eyelid muscles.

Damage of the nerve fibers can result from:

  • Injury to the carotid artery, one of the main arteries to the brain
  • Injury to nerves at the base of 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, between the lungs, and neck
  • Injections or surgery done to interrupt the nerve fibers and relieve pain (sympathectomy)
  • Spinal cord injury

In rare cases, Horner syndrome is present at birth. The condition may occur with a lack of color (pigmentation) of the iris (colored part of the eye).

What are the symptoms for Horner Syndrome?

Symptoms of Horner syndrome may include:

  • Decreased sweating on the affected side of the face
  • Drooping eyelid (ptosis)
  • Sinking of the eyeball into the face
  • Different sizes of pupils of the eyes (anisocoria)

There may also be other symptoms, depending on the location of the affected nerve fiber. These may include:

  • Vertigo (sensation that surroundings are spinning) with nausea and vomiting
  • Double vision
  • Lack of muscle control and coordination
  • Arm pain, weakness and numbness
  • One sided neck and ear pain
  • Hoarseness
  • Hearing loss
  • Bladder and bowel difficulty
  • Overreaction of the involuntary (autonomic) nervous system to stimulation (hyperreflexia)

What are the current treatments for Horner Syndrome?

Treatment depends on the underlying cause of the condition. There is no treatment for Horner syndrome itself. Ptosis is very mild and in rare cases affects vision in Horner syndrome. This can be corrected by cosmetic surgery or treated with eyedrops. The provider can tell you more.

What is the outlook (prognosis) for Horner Syndrome?

The outcome depends on whether treatment of the cause is successful.

What are the possible complications for Horner Syndrome?

There are no direct complications of Horner syndrome itself. But, there may be complications from the disease that caused Horner syndrome or from its treatment.

When should I contact a medical professional for Horner Syndrome?

Call your provider if you have symptoms of Horner syndrome.



Balcer LJ. Pupillary disorders. In: Liu GT, Volpe NJ, Galetta SL, eds. Liu, Volpe, and Galetta's Neuro-Ophthalmology. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 13.

Guluma K. Diplopia. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 18.

Thurtell MJ, Rucker JC. Pupillary and eyelid abnormalities. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 18.

  • Journal: Archivos de la Sociedad Espanola de Oftalmologia
  • Published —
Paediatric Horner syndrome. A case series of 14 patients in a tertiary hospital.
  • Journal: Journal of cataract and refractive surgery
  • Published —
Spontaneous filtering bleb with subsequent secondary glaucoma June consultation #1.