Horner syndrome

Definition

• Sympathetic chain disruption
• Miosis, partial ptosis and anhydrosis (+/- enophthalmos = inset eyelid)

Normal anatomical pathway

• Oculosympathetic pathway made up of 3 neurons
• 1st order neuron
  • Hypothalamus → SC (cervical C8-T2)
• 2nd order
  • SC (cervical) to Superior cervical ganglia
  • Via inferior and middle along the chain
• 3rd order
  • Superior cervical ganglia along CCA to ICA and ECA plexi
    • ICA plexi
      • Pupillary constrictor - pupil dilation (mydriasis)
      • Muller’s muscle (superior tarsal muscle) - ptosis
        • Only partial ptosis as the levator palpebrae superioris is still innervated by CN3 and it is only the Superior tarsal muscle that has lost innervation
      • Sweat glands to forehead
    • ECA plexi
      • Sweat glands to rest of face

Differential diagnosis

• 1st order neuron
  • Injury above T1
  • Stroke
  • Brain tumour
  • Trauma
  • Syringomyelia
• 2nd order neuron
  • Pancost tumour
  • Thyroid cancer
  • Cervical rib on superior cervical ganglion
• 3rd order neuron
  • ICA dissection or aneurysm
  • Cavernous sinus thrombosis
  • Nasopharyngeal carcinoma
  • Carotid body tumour

Clinical examination

• Cocaine eye drop test
  • Normally NE causes pupil dilatation
  • Cocaine blocks NE reuptake = more NE available
  • So with cocaine should normally have dilatation
  • But in Horner’s with non intact system = no change
• Apraclonidine eye drop test
  • It is weak NE so should normally cause some dilatation
  • Net effect = degree of difference (anisocoria) between the 2 eyes should diminish
  • Alpha 1 and alpha 2 effect of NE

Investigations

• CT/MRI to assess for cause
  • Head, neck and chest
• Localisation = Hydroxyamphetamine
  • 1st or 2nd order neuron issue (preganglionic)
    • Hydroxyamphetamine will DILATE THE MIOTIC HORNERS PUPIL
    • If there is an underlying preganglionic lesion
  • If it doesnt dilate with hydroxyamphetamine
    • = postganglionic or 3rd order neuron issue
• Regardless they need investigation with imaging

Summary

• Neuroanatomy and causes
  • 1 = hypothalamus to cervical SC C8-T2
    • Stroke
    • Brain tumour
    • Trauma
    • Syringomyelia
  • 2 = cervical SC C8-T2 to superior cervical ganglion (through brachial plexus and over lung apex)
    • Pancost tumour
    • Thyroid cancer
    • Kulmpke (brachial plexus trauma)
    • Cervical rib on sup cervical ganglion
  • 3 = superior cervical ganglion to ECA and ICA plexi (constrictor, muller, sweat of forehead/sweat of rest of face respectively)
    • ICA dissection/aneurysm
    • Cavernous sinus thrombosis
• Clinical = SPAM
  • Sympathetic
  • Ptosis (partial)
  • Anhidrosis
  • Miosis
• Testing
  • Cocaine drops - no dilation if horners
  • APRACLONIDINE = reduced anisocoria
  • Hydroxyamphetamine = dilates a 1st or 2nd order but not a 34d
• Imaging
  • CT/MRI of head, neck and chest