Horner syndrome is a combination of small pupil, drooping eyelid, and reduced sweating on one side of the face.
Underlying problem
It results from disruption of the sympathetic nerve pathway that runs from the brain to the eye and face. Many different conditions can affect this long route.
- Neck or chest tumours compressing the nerve
- Carotid artery dissection tear in the vessel wall
- Brainstem stroke or demyelinating disease
- Trauma or surgery affecting the neck or upper chest
Symptoms patients may notice
Changes are often subtle but important. Unequal pupils may be more obvious in dim light.
- Mild drooping of the upper lid with a slightly raised lower lid
- Smaller pupil on the affected side
- Different sweating pattern or facial flushing
- Associated neck pain or headache in some serious causes
