Horner syndrome

Horner syndrome classically presents as an ipsilateral blepharoptosis, pupillary miosis and facial anhydrosis due disruption at some point of the oculosympathetic pathway. The ptosis is due to interruption of the sympathetic control of the levator palpebrae superioris muscle, which controls elevation and retraction of the upper eyelid.


Horner syndrome can be anatomically classified into three types, depending on where the pathology affects the sympathetic pathway 1. Interestingly, post-ganglionic lesions do not tend to present with anhydrosis, as opposed to central or pre-ganglionic lesions. 

  • central: involves the first order neurone that starts in the hypothalamus and descends down the brainstem to the level between C8 and T2
  • pre-ganglionic: involves the second order neurone that passes from the brainstem to the superior cervical ganglion in the neck
  • post-ganglionic: involves the third order neurone that ascends along the internal carotid artery to enter the cavernous sinus, where it joins the ophthalmic division of the trigeminal nerve

There is an extremely long list of causes. The main ones include 3:

Central causes

Pre-ganglionic causes
  • apical lung mass/tumour (Pancoast tumour)
  • cervical rib
  • cervicothoracic spine 
    • trauma
  • brachial plexus injury
  • thyroid mass / goitre / tumour
  • mediastinal mass tumour
  • common carotid artery pathology
  • injury to superior cervical ganglion
Post-ganglionic causes
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Article information

rID: 7463
Synonyms or Alternate Spellings:
  • Horner's syndrome
  • Oculosympathetic palsy

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Cases and figures

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    Figure 1: clinical photograph - Horner syndrome
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    Case 1: ICA dissection (left)
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    Case 2: supraclavicular mass (left)
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