Question: What is (are) Horner syndrome ?
Answer: Horner syndrome is a disorder that affects the eye and surrounding tissues on one side of the face and results from paralysis of certain nerves. Horner syndrome can appear at any time of life; in about 5 percent of affected individuals, the disorder is present from birth (congenital). Horner syndrome is characterized by drooping of the upper eyelid (ptosis) on the affected side, a constricted pupil in the affected eye (miosis) resulting in unequal pupil size (anisocoria), and absent sweating (anhidrosis) on the affected side of the face. Sinking of the eye into its cavity (enophthalmos) and a bloodshot eye often occur in this disorder. In people with Horner syndrome that occurs before the age of 2, the colored part (iris) of the eyes may differ in color (iris heterochromia), with the iris of the affected eye being lighter in color than that of the unaffected eye. Individuals who develop Horner syndrome after age 2 do not generally have iris heterochromia. The abnormalities in the eye area related to Horner syndrome do not generally affect vision or health. However, the nerve damage that causes Horner syndrome may result from other health problems, some of which can be life-threatening.
Source: GHR

Question: How many people are affected by Horner syndrome ?
Answer: About 1 in 6,250 babies are born with Horner syndrome. The incidence of Horner syndrome that appears later is unknown, but it is considered an uncommon disorder.
Source: GHR

Question: Is Horner syndrome inherited ?
Answer: Horner syndrome is usually not inherited and occurs in individuals with no history of the disorder in their family. Acquired Horner syndrome and most cases of congenital Horner syndrome have nongenetic causes. Rarely, congenital Horner syndrome is passed down within a family in a pattern that appears to be autosomal dominant, which means one copy of an altered gene in each cell is sufficient to cause the disorder. However, no genes associated with Horner syndrome have been identified.
Source: GHR

Question: What are the treatments for Horner syndrome ?
Answer: These resources address the diagnosis or management of Horner syndrome: - Genetic Testing Registry: Horner syndrome, congenital These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
Source: GHR