The condition is caused primarily by the interruption and destruction of the nerve fibers pathway that run from the hypothalamus (part of the brain stem) to the face. This explains why the face is greatly affected by this condition. Other predisposing factors and conditions cause for this condition to occur:
1. Lesion or injury to the cervical chain, which can affect a specific side of a person’s body.
2. Trauma to the neck. Severe whiplash can cause for this condition, too.
3. Infection – can be referring to middle ear infections
4. Tumor found on top of the lung. Lung cancer is also found connected with this condition. This is believed as one of the common causes of Horner’s syndrome. About 35% of cases with Horner’s syndrome are caused by tumors affecting the lungs and thyroid.
5. Migraine or headaches that can be in a form of clusters.
6. Stroke or cerebrovascular accident. Aneurysm is also believed to cause this condition. Vascular problems are also commonly pointed out as a root of this condition.