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Horner's syndrome is ptosis, miosis, and anhidrosis due to dysfunction of cervical sympathetic output.

Etiology

Horner's syndrome results when the cervical sympathetic pathway running from the hypothalamus to the eye is disrupted. The causative lesion may be primary (including congenital) or secondary to another disorder. Lesions are usually divided into

• Central (eg, brain stem ischemia, syringomyelia, brain tumor)
• Peripheral (eg, Pancoast's tumor, cervical adenopathy, neck and skull injuries, aortic or carotid dissection, thoracic aortic aneurysm)

Peripheral lesions may be preganglionic or postganglionic in origin.

Symptoms and Signs

Symptoms include ptosis, miosis, anhidrosis, and hyperemia of the affected side. In the congenital form, the iris does not become pigmented and remains blue-gray.

Diagnosis

• Cocaine eye drop test
• MRI or CT to diagnose cause

Liquid cocaine 10% can be applied to the affected eye; poor pupillary dilation after 30 min indicates Horner's syndrome. If results are positive, 1% hydroxyamphetamine solution or 5% N-methyl hydroxyamphetamine can be applied to the eye 48 h later to determine whether the lesion is preganglionic (if the pupil dilates) or postganglionic (if the pupil does not dilate). Patients with Horner's syndrome require MRI or CT of the brain, spinal cord, chest, or neck, depending on clinical suspicion.

Treatment

The cause, if identified, is treated; there is no treatment for primary Horner's syndrome.

Last full review/revision November 2009 by Phillip Low, MD

Content last modified November 2009