Horner syndrome

An interruption of the sympathetic nerve supply to the eye should produce the classic triad of:

  • miosis — constricted pupil
  • ptosis, partial — drooping of the upper eyelid
  • anhidrosis — loss of hemifacial sweating


A Horner syndrome will not be seen where the lesion lies below the level of T2.

The stellate ganglion is intimately related to the pleura overlying the lung apex.
The stellate ganglion is intimately related to the pleura overlying the lung apex.

The finding of a Horner syndrome on examination should prompt one to look, specifically, for signs of a lateral medullary syndrome:

  • nystagmus to the side of the lesion
  • ipsilateral V nerve palsy
  • ipsilateral IX and X  nerve palsies
  • ipsilateral cerebellar signs
  • contralateral pain / temperature sensation reduced to trunks and lower limbs


  • Brainstem
    • vascular disease — Lateral Medullary (Wallenberg) Syndrome
    • Demyelination — Multiple Sclerosis
    • Syringobulbia
  • Lung
    • apical carcinoma (Pancoast tumour)
  • Neck
    • malignancy — e.g. thyroid
    • trauma / surgery
    • syringomyelia
  • Head
    • carotid aneurysm
    • peri-carotid tumours
    • cluster headache
sympathetic and parasympathetic innervation of the pupil and sites of lesion in a Horner's syndrome (sympathetic lesion) [Image: wikimedia]
Autonomic innervation of the pupil and sites of lesion in a Horner’s syndrome (sympathetic lesion) 1.sympathetic fibers arise from the hypothalamus 2.stellate ganglion 3.synapse at the superior cervical ganglion 4.sympathetic plexus around internal carotid artery 5.oculomotor nerve (Cranial nerve 3) fibers synapse at the ciliary ganglion (blue) 6.Short ciliary nerves from ciliary ganglion carrying parasympathetic supply to sphincter pupillae (green) 7.Trigeminal fibers (Cranial nerve 5) relay in ciliary ganglion and carry sympathetic supply (yellow) 8.Long ciliary nerve fibers (from the ophthalmic branch of CN 5) are the afferent limb of the blink reflex carrying sensory information from the cornea. 9.Sphincter pupillae (circular fibers) and Dilator pupillae (radial fibers) muscles of the pupil. Near the stellate ganglion, the sympathetic fibers go around the sublavian artery (shown along with the carotid vessels). This is a site of lesion especially due to its proximity to the apex of the lung (eg. Pancoast’s tumor). The superior division of oculomotor nerve is shown supplying the Superior rectus and levator palpebrae superioris. [Image and Text: Wikimedia]


From Optic Nerve Carotid Artery

Horner’s syndrome is a monocular loss of sympathetic innervation to the eye. This causes a loss of function in all of the ocular structures that are sympathetically controlled. The pupil is smaller, but the light reaction remains normal. In 90% of cases, there is a ptosis of the upper lid, caused by paresis of Muller’s smooth muscle within the palpebral levator muscle complex. At the same time there is a small elevation of the lower lid as well, since the lower lid retractors are also sympathetically innervated. The narrowing of the palpebral fissure causes the appearance described as “apparent enoph-thalmos.” If the site of damage to the sympathetic path lies proximal to the branching of the fibers that mediate sweating and temperature regulation in the face, these functions will also be impaired. The face will appear flushed on one side, with a sharp dividing line that runs precisely along the sagittal midline.



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