• Disease Overview
  • Synonyms
  • Signs & Symptoms
  • Causes
  • Affected Populations
  • Disorders with Similar Symptoms
  • Diagnosis
  • Standard Therapies
  • Clinical Trials and Studies
  • References
  • Programs & Resources
  • Complete Report

Horner’s Syndrome


Last updated: May 27, 2008
Years published: 1991, 1998, 2003

Disease Overview

Horner syndrome is a relatively rare disorder characterized by a constricted pupil (miosis), drooping of the upper eyelid (ptosis), absence of sweating of the face (anhidrosis), and sinking of the eyeball into the bony cavity that protects the eye (enophthalmos). These are the four classic signs of the disorder.

The congenital, and more rare, form of Horner syndrome is present at birth but the cause is not known. Most often, Horner syndrome is acquired as a result of some kind of interference with the sympathetic nerves serving the eyes. The underlying causes can vary enormously, from a snake or insect bite to a neck trauma made by a blunt instrument.

  • Next section >
  • < Previous section
  • Next section >


  • Bernard-Horner Syndrome
  • Oculosympathetic Palsy
  • < Previous section
  • Next section >
  • < Previous section
  • Next section >

Signs & Symptoms

The characteristic physical signs and symptoms associated with Horner syndrome usually affect only one side of the face (unilateral). These include drooping upper eyelid; contracted pupil; dryness (lack of sweating) on the same side of the face (ipsilateral) as the affected eye; and retraction of the eyeball.

If the onset of Horner syndrome is before two years of age, the colored portions of the eyes (irises) may be different colors (heterochromia iridis). In most cases, the iris of the affected side lacks color (hypopigmentation).

  • < Previous section
  • Next section >
  • < Previous section
  • Next section >


Horner syndrome may result from any one of a variety of factors, including carotid artery dissection; the development of a tumor in neck or chest cavity, particularly a neuroblastoma and a tumor of the upper part of the lung (Pancoast tumor); the development of a lesion in midbrain, brain stem, upper spinal cord, neck, or eye orbit; inflammation or growths affecting the lymph nodes of the neck; and/or surgery or other forms of trauma to the neck or upper spinal cord.

In most cases, the physical findings associated with Horner syndrome develop due to an interruption of the sympathetic nerve supply to the eye due to a lesion or growth. The lesion develops somewhere along the path from the eye to the region of the brain that controls the sympathetic nervous system (hypothalamus). The sympathetic nervous system (in conjunction with the parasympathetic nervous system) controls many of the involuntary functions of glands, organs, and other parts of the body.

Some cases of Horner syndrome occur for no other apparent reason or unknown cause (idiopathically). In other cases, some clinical researchers believe the disorder may be inherited as an autosomal dominant genetic trait.

Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22, and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome, and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 11p13” refers to band 13 on the short arm of chromosome 11. The numbered bands specify the location of the thousands of genes that are present on each chromosome.

Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.

All individuals carry a few abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.

  • < Previous section
  • Next section >
  • < Previous section
  • Next section >

Affected populations

Horner syndrome is a rare disorder that affects males and females in equal numbers and may occur at any age, among any ethnic grouping in any geographic location.

  • < Previous section
  • Next section >
  • < Previous section
  • Next section >


The diagnosis of Horner syndrome and the localization of the lesions that cause the disorder can be determined by pharmacological tests combined with imaging techniques such as magnetic resonance imaging and ultrasonography of the carotid artery.

  • < Previous section
  • Next section >
  • < Previous section
  • Next section >

Standard Therapies


The treatment of Horner syndrome depends on the location and cause of the lesion or tumor. In some cases surgical removal of the lesion or growth may be appropriate. Radiation and chemotherapy may be beneficial to patients with malignant tumors.

Genetic counseling may be of benefit for patients and their families if they have the genetic form of this disorder. Other treatment is symptomatic and supportive.

  • < Previous section
  • Next section >
  • < Previous section
  • Next section >

Clinical Trials and Studies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.

For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:


  • < Previous section
  • Next section >
  • < Previous section
  • Next section >



Salvesen R. Horner Syndrome. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:648.

Beers MH, Berkow R., eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:1455.

Adams RD, Victor M, Ropper AA. Eds. Principles of Neurology. 6th ed. McGraw-Hill Companies. New York, NY; 1997:538.

Kanski JJ. Ed. Clinical Ophthalmology. 4th ed. Butterworth-Heinemann. Oxford, UK; 1999:612-13.

Berkow R., ed. The Merck Manual-Home Edition.2nd ed. Whitehouse Station, NJ: Merck Research Laboratories; 2003:329, 592.


Patel S, Ilsen PF. Acquired Horner’s syndrome: clinical review. Optometry. 2003;74:245-56.

Leuchter I, Becker M, Mickel R, et al. Horner’s syndrome and thyroid neoplasms. ORL J Otorhinolaryngol Relat Spec. 2002;64:49-52.

Fetzer SJ. Recognizing Horner’s syndrome. J Perianesth Nurs. 2000;15:124-28.

Stapf C, Elkind MS, Mohr JP. Carotid artery dissection. Annu Rev Med. 2000;51:329-47.


Chandrasekhar S, Peterfreund RA. Horner’s syndrome following very low concentration Bupivacaine infusion for labor epidural analgesia. J Clin Anesth. 2003;15:217-19.

Matthews BD, Bui HT, Harold KL, et al. Thoracoscopic sympathectomy for palmaris hyperhidrosis. South Med J. 2003;96:254-58.

Moster ML, Galiani D, Garfinkle W. False negative hydroxyamphetamine test in horner syndrome caused by acute internal carotid artery dissection. J Neuroophthalmol. 2003;23:22-23.

Miura J, Doita M, Miyata K, et al. Horner’s syndrome caused by a thoracic dumbbell-shaped schwannoma: sympathetic chain reconstruction after a one-stage removal of the tumor. Spine 2003;28:E33-36.

Miller PR, Fabian TC, Croce MA, et al. prospective screening for blunt cerebrovascular injuries: analysis of diagnostic modalities and outcomes. Ann Surg. 2002;236:386-93; discussion 393-35.

McDonnell JF, Ramonas K, Park AH. Pediatric Horner’s syndrome due to a cervical thymic rest. J Pediatr Ophthalmol Strabismus. 2002;39:185-86.

Bandyk DF, Johnson BL, Kirkpatrick AF, et al. Surgical sympathectomy for reflex sympathetic dystrophy syndromes. J Vasc Surg. 2002;35:269-77.

Chan CC, Paine M, O’Day J. Carotid dissection: a common cause of Horner’s syndrome. Clin Experiment Ophthalmol. 2001;29:411-15.


McKusick VA, Ed. Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Horner Syndrome. Entry Number; 143000: Last Edit Date; 9/24/94.

Horner’s Syndrome. Handbook of Ocular Disease Management. nd. 2pp.


Moses S. Horner’s Syndrome. Family Practice Notebook. ©2000. 2pp.


Horner’s Syndrome. EyeMDLink. ©2002. 2pp.


Horner’s Syndrome. Med Help International. Various dates. Various pages.


  • < Previous section
  • Next section >

Programs & Resources

RareCare® Assistance Programs

NORD strives to open new assistance programs as funding allows. If we don’t have a program for you now, please continue to check back with us.

Additional Assistance Programs

MedicAlert Assistance Program

NORD and MedicAlert Foundation have teamed up on a new program to provide protection to rare disease patients in emergency situations.

Learn more https://rarediseases.org/patient-assistance-programs/medicalert-assistance-program/

Rare Disease Educational Support Program

Ensuring that patients and caregivers are armed with the tools they need to live their best lives while managing their rare condition is a vital part of NORD’s mission.

Learn more https://rarediseases.org/patient-assistance-programs/rare-disease-educational-support/

Rare Caregiver Respite Program

This first-of-its-kind assistance program is designed for caregivers of a child or adult diagnosed with a rare disorder.

Learn more https://rarediseases.org/patient-assistance-programs/caregiver-respite/

Patient Organizations

National Organization for Rare Disorders