Caused by a disruption in the sympathetic innervation to the ipsilateral maxillofacial region, is characterized by:

  1. Ptosis (by loss of sympathetic innervation to Mueller’s muscle)
  2. Anhidrosis (by interruption of sympathetic innervation to cutaneous sweat glands).
  3. Miosis or a constricted pupil (by unopposed parasympathetic constriction)
  • Remember the pnemonic, PAM is Horny (Ptosis, Anhydrosis, Miosis is Horner’s Syndrome)