horner syndrom

Horner syndrome (also spelled Horner's syndrome) is a neurological condition caused by disruption of the sympathetic nerves supplying the eye and surrounding facial structures. It is characterized by a classic triad of symptoms on the affected side of the face:

1. Ptosis – drooping of the upper eyelid due to paralysis of the superior tarsal muscle (Müller's muscle).
2. Miosis – constricted pupil due to unopposed parasympathetic activity (loss of sympathetic innervation to the dilator pupillae muscle).
3. Anhidrosis – decreased sweating on the affected side of the face because of loss of sympathetic innervation to sweat glands.

Additional features may include:

• Apparent enophthalmos (the eye appears sunken, though this is often an illusion caused by ptosis).
• Vasodilation and flushing on the affected side.

Causes / Etiology

Horner syndrome results from interruption anywhere along the sympathetic pathway to the eye:

1. First-order neuron lesion (central): From hypothalamus to spinal cord (C8-T2).

   • Causes: stroke, demyelination (e.g., multiple sclerosis), tumors, syringomyelia, brainstem lesions.

2. Second-order neuron lesion (preganglionic): From spinal cord to superior cervical ganglion.

   • Causes: Pancoast tumor (apical lung tumor), trauma, thoracic surgery, neck masses.

3. Third-order neuron lesion (postganglionic): From superior cervical ganglion along internal carotid artery into the cavernous sinus and orbit.

   • Causes: carotid artery dissection, cluster headaches, tumors near the cavernous sinus.

Diagnosis

• Clinical history and examination.

• Pharmacologic tests (sometimes used to localize the lesion):

  • Cocaine test: cocaine blocks reuptake of norepinephrine, causing dilation of normal pupil but not in Horner syndrome.
  • Apraclonidine test: in Horner syndrome, apraclonidine can cause reversal of anisocoria due to denervation supersensitivity.
  • Hydroxyamphetamine test: helps localize lesion between preganglionic and postganglionic.

• Imaging studies to identify underlying cause (MRI, CT angiography).

Treatment

Focused on treating the underlying cause (e.g., tumor removal, managing carotid dissection). The syndrome itself typically does not require direct treatment.

If you want, I can provide more detailed information about the pathway, diagnostic testing, or management.