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Pupillary Signs in Head Injury 6/8/10 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 PaCO2: ACIDOSIS: DIABETES: giant cell arteritis, syphyllis, hypertension -> IIIrd nerve palsy without dilated pupil Jeremy Fernando (2011)
