Brain and Behavior: Neuro-ophthalmology

Superior fibers from optic radiation (representing the inferior field) travel via the …

parietal lobe

Inferior fibers from the optic radiation (representing the superior field) travel via the …

temporal lobe

…: lesion at the optic nerve

monocular visual loss

…: lesion at the optic chiasm

bitemporal hemianopia

…: lesion at right optic tract

homonymous hemianopia

…: lesion at left temporal radiation

upper homonymous quadrantanopia

…: lesion at left parietal radiation (meyers loop)

lower homonymous quadrantanopia

…: lesion at right occipital pole

homonymous hemianopia

…: unilateral visual loss

retinal detachment

…: bilateral and asymmetrical often arcuate patterned visual loss

glaucoma

…: unilateral, hemifield respecting the horizontal midline

ischemic optic neuropathy

…: central visual loss, most common in the western world

age-related macular degeneration

Sympathetic innervations: …

Iris dilator, muller muscle of eyelid

…: elevates eyelid by 2mm

muller muscle

Parasympathetic innervation: … (2)

iris sphincter, ciliary body muscle

…: contracts, in charge of accomodation

ciliary body muscle

…: loss of the accomodation reflex with age and following cataracts surgery

presbyopia

Accommodation reflex: … → … → … → …

stimulus close to eyes, ciliary body constricts, zonular fibers relax, lens becomes convex

Two eyelid elevation muscles: … (2)

LPS, muller muscle

…: innervates the elevation eyelid muscles

CN III

…: closes the eyelids

Orbicularis oculi

…: innervates the orbicularis oculi

CN VII

Causes of horner’s syndrome: … (3)

Pancoast tumor, carotid dissecting aneurysm, congenital

Pupillary light reflex pathway: … → … → … → … → … → … → … (7)

light stimulates retina, optic nerve, few nerves leave optic tract, parasympathetic nucleus, back to eye CN III, innervate iris sphincter, pupil constricts

Test of the afferent pathway in relative afferent pupillary defect compares one … to the same intensity of light in the other eye

optic nerve response

Fundoscopy of the optic nerve checks for the three C’s: … (3)

color, contour, cup

The pink area seen in optic nerve fundoscopy is …

neuroretinal rim

The white area seen in optic nerve fundoscopy is …

underlying sclera

…: identified with loss of disc margin (contour), assess optic nerve function → visual acuity, color vision, RAPD, visual fields

Optic nerve unilateral disc swelling

Causes of unilateral disc swelling: … (4)

optic neuritis, ischemic optic neuropathy, central retinal vein occlusion, compression

…: associated with MS (demyelination) much more common in females

optic neuritis

Optic neuritis visual effects: … (4)

reduced vision, positive RAPD, impaired color vision, increased blind spot

In optic neuritis causes pain in eye movements because … is around optic nerve/meninges

extra-ocular muscles origin

Investigations of optic neuritis: … (3)

FLAIR, Delayed visual and auditory evoked potentials, IgG in LP

Management of Optic neuritis: usually just observation of patient, … hastens visual recovery but does not affect final visual acuity

IV methylprednisone

Optic nerve prognosis: all patients will have some improvements, probability of developing …

MS

…: raised intracranial pressure, papilledema, often optic nerve function is preserved

Bilateral disc swelling

Causes of bilateral disc swelling: … (4)

space-occupying lesion, trauma, CVA, idiopathic intracranial hypertension

Oculomotor nerve III innervates: … (6)

superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae superioris

…: innervates the lateral rectus

CN VI abducens

…: innervates superior oblique, longest and finest cranial nerve, commonest cause of acute IV palsy is head trauma, even relative minor trauma

CV IV trochlear

Parasympathetic eye reflexes: … (2)

iris sphincter constriction, ciliary muscle accommodation

The parasympathetic fibers of pupil constriction control pupil constriction and ciliary muscle accommodation, these fibers run on the outside of the nerve and are supplies by …

pial blood vessels

The motor fibers of eye movement and eyelid lifiting are in the core of the nerve and are supplied by …

vasa vasorum

…: external compression of the nerve, posterior communicating artery aneurysm, head trauma, tumors,

surgical lesions

Findings of surface compression of the oculomotor nerve: … (3)

ptosis, down and out eye, blown pupil

…: cause microangiopathy, damage to the vasa vasorum → ischemia of the core of the nerve

medical lesions

… think aneurysm until proven otherwise

pupil-involving CN III palsy

… think diabetes or hypertension

pupil-sparing CN III palsy

Combined unilateral palsies of III, IV and VI nerves occur from lesions along their peripheral pathway course where they are in close proximity to: … (3)

cavernous sinus, superior orbital fissure, orbit

Oculomotor differential diagnosis: … (6)

aneurysm, ischemic, cavernous sinus thrombosis, vasculitis, MS, MG

Trochlear differential diagnosis: … (3)

congenital, trauma, vascular

Oblique diplopia in trochlear palsy is worse upon …

downgaze

… is false localizing sign as increased intracranial pressure readily causes VI nerve paralysis often bilaterally

CN VI palsy

CN VI is vulnerable to injury as it crosses the sharp edge of the …

petrous temporal bone

Each rectus muscle has 2 anterior ciliary vessels except for the lateral rectus muscle which has …, increased risk of microvascular compromise

1 ciliary vessel

Lateral rectus differential diagnosis: … (2)

vasculopathy, raised ICP

Always asses … and fundoscopy in patients with VI palsy

CN V

Motor innervations of the trigeminal nerve: … (5)

muscles of mastication, anterior digastric, mylohyoid, tensor tympani, tensor palatini

Sensory innervations of trigeminal nerve: … (8)

muscles of mastication, TMJ, face, scalp, cornea, oral, mucosal cavities, meninges

In trigeminal deficits the jaw deviates to the …

paralysed side

Motor trigeminal examinations: … (2)

clench teeth (masseter and temporalis), open mouth against resistance (pterygoids)

Trigeminal herpes zoster ophthalmic symptoms: … (7)

headaches, paresthesia, malaise, rash, ocular keratitis, krutovites, raised intraocular pressure

Motor innervations of facial nerve function: … (2)

muscles of facial expression, stapedius

Sensory innervations of facial nerve function: … (4)

anterior 2/3 of tongue, flood of mouth, palate, external ear

Parasympathetic innervations of facial nerve: … (3)

lacrimal gland, submandibular gland, sublingual gland

Facial nerve enters …, a narrow bony canal, travels in close proximity to VIII

internal auditory meatus

UMN dysfunction: … (6)

late wasting, no fasciculations, increased tone, decreased power, increased reflexes, babinski

LMN dysfunction: … (5)

early muscle wasting, fasciculations, decreased tone, decreased power, decreased reflexes

…: sudden onset, facial asymmetry, speech difficulty, dry eye and mouth, discomfort around ear

bells palsy