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Horner’s Syndrome

Overview

Horner’s syndrome is a rare condition caused by damage to the sympathetic nerves (the nerves that control automatic functions such as pupil size, sweating, and eyelid movement) on one side of the face. This nerve damage leads to changes in the eye and reduced sweating on the affected side.

Common signs and symptoms may include:

  • Small-sized pupil on the affected side
  • Eye retraction (sunken appearance)
  • Drooping of eyelid or elevation of lower eyelid
  • Decreased sweating over the affected side of the face
  • Pale skin on the same side of the face

Horner’s syndrome can occur when the nerve pathway from the brain to the eye is interrupted. Causes include:

  • Lesion of the primary neuron
  • Lesion of the postganglionic neuron
  • Trauma to the brachial plexus (nerve network of the arm and shoulder)
  • Lesions in the brain and spinal cord (brainstem tumour, stroke, syrinx)
  • Carotid artery injury (including dissection or reduced blood flow)
  • Tumours (e.g. Pancoast tumour) or infection at the lung apex
  • Internal jugular vein catheterisation
  • Brain or skull base tumours (Middle cranial fossa neoplasm)
  • Migraine

To confirm Horner’s syndrome and identify its cause, doctors may recommend:

  • Clinical examination: of pupil size, eyelid position, and sweating patterns
  • Imaging tests: such as MRI or CT scan of the brain, neck, or chest to look for stroke, tumours, or vessel damage
  • Pharmacological tests: using special eye drops to check abnormal pupil response
  • Vascular studies: to assess carotid artery or blood vessel damage

There is no specific cure for Horner’s syndrome itself. Treatment focuses on managing the underlying cause, such as:

  • Removing or treating tumours
  • Managing stroke or aneurysm
  • Repairing carotid artery dissection
  • Treating infections or inflammation
  • Managing headaches or migraines

Seek immediate medical attention if you develop:

  • Sudden drooping eyelid and small pupil on one side of the face
  • Severe headache or neck pain (possible carotid artery dissection)
  • Sudden vision changes, weakness, or confusion (possible stroke)

Since Horner’s syndrome is usually caused by underlying conditions, prevention focuses on:

  • Managing cardiovascular risks (blood pressure, diabetes, cholesterol)
  • Avoiding head/neck trauma when possible
  • Timely treatment of infections and tumours

For diagnosis and management of Horner’s syndrome, consult a:  

  • Neurologist (for diagnosis and management of nerve-related causes)
  • Ophthalmologist (for evaluation of eye-related symptoms)
  • Neurosurgeon or vascular specialist (if caused by stroke, aneurysm, or tumour)

Disclaimer:

The information in this Health Library is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional with any questions about a medical condition or before starting any treatment. Use of this site and its content does not establish a doctor–patient relationship. In case of a medical emergency, call your local emergency number or visit the nearest emergency facility immediately.