What is Horner syndrome

Horner syndrome is a condition caused by injury to the sympathetic nerves fo the face.
A syndrome is a combination of different signs and symptoms, when put together, have certain clinical significance.
Horner syndrome is characterised by these 3 signs:

  • Constricted pupils (the tiny black part of the eye)
  • Drooping eyelids (ptosis)
  • Facial dryness due to inability to sweat (anhidrosis)
  • The significance of Horner syndrome lies in the underlying diseases that cause this syndrome, rather than a clinical disease by itself.

    Statistics on Horner syndrome

    Horner syndrome is an uncommon to rare condition. There is no statistical data on the incidence of Horner syndrome because it is the causative factor that is important.

    Risk Factors for Horner syndrome

    There is no racial, gender, and age predilection.

    Progression of Horner syndrome

    It is important to understand the anatomy of sympathetic nerves supplying the eye. There are 3 group of nerves supplying the sympathetic function of the eyes. The following describes the path of the different nerve fibres:

  • The first travels from the middle of the brain (hypothalamus) to the neck spinal cord (cervical spine)
  • The second travels from the neck spinal cord to the outside of spinal cord
  • Third order neurons travel via the outside of spinal cord near the carotid artery (neck artery that can be felt) to the eye
  • The last fibres provide innervation to several tissues:
  • Muscle that dilates the pupil
  • Muscle that raises the eyelid
  • Sweat glands of the face, which is responsible for facial sweating
  • In Horner syndrome, there is disruption to this whole chain of sympathetic nerves. Hence it is important to find out the cause of this.There are many causes of Horner syndrome, but the most sinister one would be a lung cancer sitting on the tip of the lungs, slowing invading the nerve tissue.

    How is Horner syndrome Diagnosed?

    Depending on the cause, the patient may need general routine investigations, especially if the cause cannot be explained by clinical history and examination. These include looking at the blood function, kidney function, liver function, thyroid function, and the body’s iron, vitamins and electrolytes level.

    Prognosis of Horner syndrome

    The prognosis depends on the diseases that cause Horner syndrome.

    How is Horner syndrome Treated?

    Treatment aims at the underlying causes and will not be discussed here. It is important to detect this syndrome early and refer early to appropriate specialists.
    However, there is no effective treatment for this syndrome per se. If drooping eyelids are a cosmetic problem, surgery can be done.

    Horner syndrome References

    [1] American Academy of Ophthalmology: Basic and Clinical Science Course: Neuro-ophthalmology. 1999-2000; 5: 97-99
    [2] Amonoo-Kuofi H.S. Horner’s syndrome revisited with an update of the central pathway. Clin Anat. 1999; 12: pp 345-361.
    [3] eMedicine: Horner Syndrome [online]. 2004. [Cited 2005 October 23rd]. Available from: URL: http://www.emedicine.com/med/topic1029.htm
    [4] Medicdirect: Horner’s syndrome [online]. 2004. [Cited 2005 October 23rd]. http://www.medicdirect.co.uk/diseases/default.ihtml?pid=1371&step=4
    [5] Ross I.B. The role of Claude Bernard and others in the discovery of Horner’s Syndrome. J Am Coll Surg. 2004; 199: pp 976-980