Disruption of sympathetic chain to the face

Characterised by:

1. Small pupil (miosis)
   • Loss of sympathetic innervation → pupillary contraction
2. Eyelid droop (ptosis)
   • Sympathetic system supplies superior tarsal muscle
   • Assists levator palpebrae in raising eyelid
3. No sweat (anhidrosis)

Causes:

• Apical lung tumour
• Aortic dissection
• Carotid dissection
• PICA Stroke (Lateral medullary syndrome)