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Pupillary Signs in Head Injury
SP Notes
Pupillary signs in the head injured patient are dependent on a number of factors including:
integrity of the eyes and retina
optic nerve
oculomotor nerve
trochlear nerve
abducens nerve
the respective nerve nuclei for above nerves
also the structures surrounding the above nerves and nuclei
Puplliary Signs
EQUAL AND REACTIVE TO LIGHT – normal integrity of the above structures
MIOSIS – interruption of the sympathetic innervation or irritation of the conjunctivae or
cornea (foreign bodies) -> mediated by the constrictor muscle (preganglionics = oculomotor
nerve -> ciliary ganglion -> post ganglionics to constrictor muscles releasing Ach)
MYDRIASIS – parasympathetic innervation originates in the Edinger-Westphal subnucleus of
the IIrd nerve -> compressive lesions affect autonomic fibers as they are very superficial in
the nerve trunk (sympathetic preganglionics from thoracic region -> superior cervical ganglia
-> postganglionic neurons releasing noradrenaline -> dilator muscle in iris
ANISOCORIA – unilateral lesions along any of the above tracts
IRREGULAR SHAPED PUPILS – ophthalmological procedures
OVAL PUPILS – early compression of IIIrd nerve due to increased ICP
ONE EYE ‘DOWN AND OUT’ – dysfunction of the IIIrd cranial nerve or nuclei
Pharmacological Factors
MIOSIS: opioids, alcohol, neuroleptics
MYDRIASIS: anticholinergics, catecholamines, cocaine, amphetamines
PUPIL REACTIVITY: opioids, propofol, metoclopramide, haloperidol, droperidol
Metabolic Factors
DIABETES: giant cell arteritis, syphyllis, hypertension -> IIIrd nerve palsy without dilated
Jeremy Fernando (2011)