Cranial Nerves

Pupillary Defects


Horner’s Syndrome

  • Horner's syndrome is a classic triad that occurs due to compression of the sympathetic chain.
    • Look For

    • Partial ptosis: drooping of the eyelid
    • Miosis: pupillary constriction
    • Anhidrosis: lack of sweating
    • Causes of Horner's Syndrome

    • Brain lesion - hypothalamus, thalamus, pons, medullaTumour, bleed
    • Spinal cord lesionTrauma, inflammation, AVM, demyelination, tumour, infarct
    • Apical lung lesion (Pancoast syndrome)
    • Brachial plexus lesion

Oculomotor Nerve (III) Palsy

    • Look For

    • Eye deviated down and out
    • Diplopia
    • Ptosis
    • Mydriasis: pupillary dilatation
    • Loss of pupillary reflexes
    • Causes of Occulomotor Nerve Palsy

    • Small-vessel ischaemia
    • Midbrain infarct
    • Head trauma
    • Tumour
    • Aneurysm (commonly PCA)

Adie’s Tonic Pupil

    • Look For

    • Dilatation of one or both pupils
    • Unresponsiveness to light
    • Intact accomodation reflex (near light dissociation)
    • Significance

    • Indicates loss of postganglionic parasympathetic innervation of the sphincter pupillae and ciliary muscles.
  • This finding is commonly associated with knee / ankle areflexia (Holmes-Adie syndrome)
    • Causes of Adie's Tonic Pupil

    • Viral infection
    • Trauma
    • Orbital tumour
    • Vasospasm (migraine)
    • Idiopathic

Argyll Robertson Pupil

    • Look For

    • Pupillary constriction
    • Unresponsiveness to light
    • Intact accomodation reflex (near light dissociation)
    • Significance

    • Previously pathognomonic for neurosyphillis, though more recently associated with conditions affecting the Edinger Westphal nucleus (accessory occulomotor nucleus) within the midbrain.
Last updated on January 6th, 2020
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