5 Pupils + Ptosis Flashcards
Palpebral fissure measurement and ptosis requirement:
12-15mm normally
Upper marginal reflex (reflex to up. Lid) <2mm or asymmetry of 2mm
Muscles in upper lid opening:
Levator primary superioris, supplied by sup. Division of oculomotor nerve (CV 3)
Modified by mullers; sympathetic smooth muscle (arousal/excitement
Orbicularis oculi / frontalis muscle (facial nerve, CV 7)
LPS function assessment:
Lid difference in upgaze and downgaze while holding eyebrow (frontalis involvement
Fatigue assessed by 60s upgaze
Causes of ptosis:
Disinsertion of LPS (most common) Myasthenia gravis / Graves (muscular) Horners (sympathetic) CN3 palsy Globe retraction / eyelid swelling Fatigue/trauma
Disinsertion of LPS:
Lid dehiscence/aponeurotic ptosis
LPS tendon less from tarsal from rubbing, CLs, trauma/surgery
Low lid, high crease, normal range of motion
Treated with LPS shortening
Myathenia gravis:
Autoimmune against acetylcholine receptors of striated muscle.
Fatigue, facial weakness, ptosis (LPS weak)/diplopia.
Cognan’s lid twitch (upper lid overshoot on upgaze)
Curtaining/enhanced ptosis (contralateral drooping/elevation)
Curtaining/enhanced ptosis:
Curtining, manual potoc elevation lowers normal
Enhances ptosis, manual normal elevation lowers potic moreso
Herings law of equal innervation to paired yoke muscles (potic processes less of the same innervation)
Causes of anisocoria:
Physiological (aysymetric inhibition of edinger-westphal) Horners CN3 palsy Adies tonic pupil Pharmacological Pupil damage Acute angle glaucoma
Mitochondrial myopathy in ptosis:
Mitochondrial dysfunction leads to fatigue of EOMs
Bilateral ptosis, ophthalmoplegia (weak motility)
CN3 palsy:
Lesion to CN3, often unilateral
Ptosis, mydriasis (depending on cause), down and out turn, headache.
Aberrant regeneration > miosis
Pupil-involving/sparing CN3 palsy:
Involving, mass/aneurysm/trauma causing compression and ischemia of parasympathetic fibres
Sparing, diabetes/hypertension > ischemia of nerve trunk, sparing outer fibres
CN3 palsy lesion site and cause:
Subarachnoid (trauma/aneurysm)
SO fiss./cavernous sinus (trauma/tumor)
Orbit (trauma)
Full lesion (multiple sclerosis)
Superior division lesion -> no LPS innervation
Inferior division -> only lat rectus and sup. Oblique have innervation (CN6)
Pseudoptosis
Ptosis appearance unrelated to lid function
Dermatochalasia most common
CN 7 facial palsy (brow muscle loss)
Para/sympathetic iris path for miosis/mydriasis
Parasympathetic > miosis via sphincter muscle
Sympathetic > mydriasis via dilator muscle
Parasympathetic pathway for iris
Afferent: Optic nerve > split at chiasm > optic track > split before LGN > sup. Colliculus > pretectal nuclei (processed) > both edinger-westphal nuclei.
Efferent: Edinger-westphal nuclei > CN 3 > ciliary ganglion > iris sphincter