Horner's syndrome
（重定向自Horners syndrome）
![](/Images/godic/202501/18/Miosis3932.jpg")
![Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of a lesion in Horner's syndrome.](/Images/godic/202501/18/Horner's_Syndrome_and_Autonomic_innervation_of_the_eye.svg3932.png")
![Left-sided Horner's syndrome in a cat as a result of trauma, demonstrating miosis in left pupil.](/Images/godic/202501/18/Example_of_Horner's_syndrome_in_a_cat3932.jpg")
Horner's syndrome (also known as Bernard-Horner syndrome and oculosympathetic palsy) is a combination of symptoms that arises when a group of nerves known as the sympathetic trunk is damaged. The signs and symptoms occur on the same side as the lesion of the sympathetic trunk. It is characterized by miosis (a constricted pupil), ptosis (a weak, droopy eyelid), apparent anhidrosis (decreased sweating), with or without enophthalmos (inset eyeball).