Horner’s Syndrome

indrawn eye + small pupil + ptosis (± anhydrosis) → Horner syndrome (?lung cancer) as per Murtag

• Signs/Symptoms:
  • Miosis – Constricted pupil in the affected eye, leading to unequal pupil size (anisocoria)
  • Ptosis –  Incomplete  (Contrast with complete Ptosis in levator paralysis)
  • Anhidrosis – Absence of sweating on face and neck
  • Illusion of eyeball recession (No true enophthalmos)
  • Inability to open or completely close the eyelid
  • All findings are unilateral

Causes:

• First-order neurons are mostly affected by intracranial conditions and include the following:
  • Cerebral vascular accidents (CVA)
  • Multiple sclerosis
  • Arnold-Chiari malformation
  • Encephalitis
  • Meningitis
  • Lateral medullary syndrome 
  • Syringomyelia
  • Intracranial tumors (pituitary or basal skull)
  • Spinal trauma above the T2-T3 level
  • Spinal cord tumors
• Second-order neurons traverse the thoracic region and are affected by the following:
  • Malignancies involving the apex of the lungs (Pancoast tumor)
  • Cervical rib (tractional injury)
  • Lesions of the subclavian artery (an aneurysm)
  • Mediastinal lymphadenopathy
  • Trauma to brachial plexus
  • Neuroblastoma of the paravertebral sympathetic chain
  • A dental abscess involving the mandibular region
  • Iatrogenic (including thyroidectomy, radical neck dissection, tonsillectomy, coronary artery bypass grafting, or carotid angiography)
• Third-order neurons are in close proximity to the internal carotid artery and cavernous sinus and are affected by the following:
  • Carotid cavernous fistula
  • Internal carotid artery dissection or an aneurysm
  • Cluster headaches or migraines
  • Raeder paratrigeminal syndrome (unilateral facial pain, headache, and Horner syndrome)
  • Herpes zoster infection
  • Temporal arteritis

Investigations

• First-order:
  • MRI brain (structural lesions, stroke)
  • MRI cervical spine (syrinx, cervical myelopathy)
• Second-order:
  • Chest radiograph (apical lung tumour)
  • Angiogram for large artery aneurysm / dissection
• Third-order:
  • CT venogram (cavernous sinus thrombosis)