Flashcards in CN LANGE - Neuro-Ophthalmic Disorders II Deck (94):
Marcus Gunn pupil is detected by ...?
Rapidly moving a bright flashlight back and forth between the eyes while continuously observing the suspect pupil (Gunn pupillary test).
The Marcus Gunn pupil is commonly associated with ...?
Disorders of the IPSILATERAL optic nerve, which interrupt the afferent limb and affect the pupillary light reflex.
--> Such disorders also commonly impair vision (especially color vision) in the involved eye.
Optokinetic nystagmus consists of ...?
Eye movements elicited by sequential fixation on a series of targets passing in front of a patient's eyes, such as telephone poles seen from a moving train.
Optokinetic response - Testing:
Use a revolving drum with vertical stripes OR a vertically striped strip of cloth is moved across the visual field to generate these movements.
Optokinetic response - Testing produces ...?
A SLOW following phase in the direction of the target's movement, followed by a RAPID return jerk in the opposite direction.
Optokinetic response - The slow (pursuit) phase tests ...?
PARIETO-OCCIPITAL lobe function in the hemisphere toward which the stimulus is moved.
Optokinetic response - The rapid (saccadic) movement tests ...?
FRONTAL lobe function in the hemisphere toward which the stimulus is moved.
The presence of an optokinetic response reflects the ability to ...?
Perceive movement or contour and is sometimes useful for documenting visual perception in newborns or in psychogenic blindness.
Visual acuity required to produce the optokinetic response is ...?
MINIMAL. (20/400), or finger counting at 3 to 5ft.
Unilateral impairment of the optokinetic response may be found when targets are moved ...?
Toward the side of a parietal lobe lesion.
The eyelids (palpebrae) should be examined with the patient's eyes ...?
Distance between the upper and lower lids (intrapalpebral fissure) is usually ...?
Approx. 10mm and EQUAL in both eyes, though physiologic asymmetries do occur.
The position of the inferior margin of the upper lid relative to the superior border of the iris should be noted in order to detect ...?
Drooping (PTOSIS) or abnormal elevation of the eyelid (lid retraction).
The upper lid normally covers ...?
1-2mm of the iris.
3 causes of UNILATERAL ptosis:
1. Levator palpebrae muscle paralysis.
2. Lesions of the oculomotor nerve or its superior branch.
3. Horner syndrome.
BILATERAL ptosis suggests ...?
1. Oculomotor (III) nucleus lesions.
2. Lesions of the neuromuscular junction (myasthenia gravis).
3. Lesions of muscle (eg myotonic, ocular, or oculopharyngeal dystrophy).
Lid retraction is seen in ...?
2. Parinaud syndrome caused by tumors in the pineal region.
Exophthalmos - Causes include:
1. Hyperthyroidism (Graves).
2. Orbital tumor or pseudotumor.
3. Carotid artery-cavernous sinus fistula.
Exophthalmos - A bruit may be audible on auscultation ...?
Over the proptotic eye in patients with carotid artery-cavernous sinus fistula or other vascular abnormalities.
How do we detect ocular palsies and gaze palsies?
By having the patient gaze in each of the 6 cardinal positions.
What do we do if the patient is unable to cooperate with the examination (eg stuporous or comatose)?
Reflex eye movements can be induced by:
1. Doll's head (oculocephalic).
2. Cold-water caloric (oculovestibular) testing.
Oculomotor palsy - Passively elevating the paralyzed lid shows ...?
The involved eye to be LATERALLY deviated because of the unopposed action of the lateral rectus muscle, not innervated by the oculomotor nerve.
Oculomotor palsy - On attempted downgaze ...?
The unaffected superior oblique --> Causes the eye to turn INWARD.
Oculomotor palsy - Diplopia is present in ...?
ALL directions of gaze EXCEPT --> Lateral gaze toward the side of involvement.
Oculomotor palsy - Pupil function:
May be normal (pupillary sparing) or impaired.
IV palsy - During forward gaze?
The involved eye is ELEVATED during forward gaze.
--> The extent of elevation INCREASES during ADDUCTION.
--> The extent of elevation DECREASES during ABDUCTION.
IV palsy - Bielschowsky head-tilt test):
Elevation is greatest when the head is tilted toward the side of the involved eye and abolished by tilt in the opposite direction.
IV palsy - Diplopia:
Most pronounced when the patient looks DOWNWARD with the affected eye adducted (as in looking at the end of one's nose).
IV palsy - Spontaneous head tilting:
Present in approx. 1/2 of patients with UNILATERAL palsies - Greater in BILATERAL palsies.
--> Intended to decrease or correct diplopia.
VI palsy - The eye is ... at rest.
The diminished ability of a pair of yoked muscles (muscles that operate in concert to move the 2 eyes in a given direction).
Gaze palsy is caused by ...?
1. Supranuclear lesions in the brainstem.
2. Cerebral lesions.
Gaze palsy, unlike ocular palsies, ...?
Affects BOTH eyes + usually can be overcome by caloric stimulation.
Mild impairment of upward gaze is ...?
NOT UNCOMMON in normal elderly subjects.
Internuclear ophthalmoplegia (INO) results from a lesion in MLF. MLF is ...?
An ascending pathway in the brainstem that projects from the VI to the CONTRALATERAL oculomotor nerve nucleus.
INO cannot be overcome by caloric stimulation, BUT can be distinguished from oculomotor (III) nerve palsy by noting ...?
Preserved adduction with CONVERGENCE.
INO is usually caused by ...?
2. Braistem stroke.
What happens in one-and-a-half syndrome?
A pontine lesion affecting BOTH the MLF and the IPSILATERAL PPRF (lateral gaze center) produces a syndrome that combines INO + inability to gaze TOWARD the side of the lesion.
One-and-a-half syndrome - What happens?
The ipsilateral eye is IMMOBILE in the horizontal plane + Movement of the contralateral eye is restricted to ABDUCTION, which may be associated with nystagmus.
One-and-a-half syndrome - Causes:
1. Pontine infarct.
3. Pontine hemorrhage.
Nystagmus is ...?
Rhythmic oscillation of the eyes.
Occurs with equal velocity in BOTH directions.
Pendular nystagmus - Onset:
Usually in infancy.
Jerk nystagmus is characterized by ...?
A slow phase of movement in one direction, followed by a fast phase in the opposite direction.
Jerk nystagmus - The direction of nystagmus is specified by ...?
Stating the direction of the fast phase (eg leftward-beating nystagmus).
Jerk nystagmus usually ...?
Increases in amplitude with gaze in the direction of the fast phase = Alexander law.
To detect nystagmus, the eyes should be observed ...?
In the primary position and in each of the cardinal positions of gaze.
Nystagmus is described in terms of ...?
1. The position of gaze in which it occurs.
2. Its direction.
4. Precipitating factors such as changes in head position.
5. Associated symptoms (eg vertigo).
Many forms of nystagmus and related ocular oscillations have been described, but 2 syndromes of acquired PATHOLOGIC jerk nystagmus are by far the most common.
1. Gaze-evoked nystagmus.
2. Vestibular nystagmus.
Gaze-evoked nystagmus - Occurs when ...?
Occurs when the patient attempts to gaze in one or more directions away from the primary position.
Gaze-evoked nystagmus - The fast phase of the nystagmus is ...?
In the direction of gaze.
Nystagmus evoked by gaze in a single direction is a common sign of ...?
Early or mild residual ocular palsy.
Multi-directional gaze-evoked nystagmus is most often an effect of ...?
Anticonvulsant or sedative drugs, but can also result from cerebellar or central vestibular dysfunction.
Nystagmus caused by a lesion of the peripheral vestibular apparatus is characteristically ...?
UNIDIRECTIONAL, horizontal or BOTH horizontal and rotatory + associated with severe vertigo.
Vestibular nystagmus by a lesion of the peripheral vestibular apparatus - Its amplitude increases with ...?
Gaze toward the fast phase.
CENTRAL vestibular nystagmus may be ...?
Bidirectional and purely horizontal, vertical, or rotatory, and the accompanying vertigo is typically mild.
Positional nystagmus, elicited by changes in head position, can occur with ...?
Either peripheral or central vestibular lesions.
Vestibular nystagmus - Most helpful distinguishing features between peripheral and central etiology:
1. Peripheral --> Hearing loss, tinnitus.
2. Central --> Corticospinal tract or additional cranial nerve abnormalities.
Common syndromes of monocular visual loss include 2 reversible and 2 irreversible causes:
1. Transient monocular blindness.
2. Optic neuritis.
3. Idiopathic ischemic optic neuropathy.
4. Giant cell (temporal) arteritis.
Transient monocular blindness is caused by ...?
Optic nerve or retinal ischemia --> Sudden in onset + resolves rapidly.
Optic neuritis produces ...?
Subacute, painful, unilateral visual loss with partial resolution.
Transient monocular blindness is also called ...?
Transient monocular blindness - Features:
Painless, unilateral transient diminution or loss of vision that develops over seconds, remains maximal for 1 to 5min , and resolves over 10 to 20 minutes.
Transient monocular blindness - The cause of these episodes often remains uncertain ...?
Both embolic and non-embolic causes are known.
Transient monocular blindness - The risk of subsequent hemispheric stroke is increased BUT ...?
UNRELATED to the FREQUENCY + DURATION of these episodes.
Transient monocular blindness - The risk of subsequent hemispheric stroke is only ...?
1/2 of that in patients with hemispheric TIAs.
Inflammation of the optic nerve.
Optic neuritis - MCC is ...?
Demyelination (acute demyelinating optic neuritis).
Optic neuritis - Less common causes include:
3. Intraocular inflammation.
associated with viral infections or postviral syndromes.
Rare causes of optic neuritis include:
1. Toxins (eg methanol, ethambutol).
3. B12 def.
Optic neuritis - Unilateral impairment of visual acuity occurs over ...?
Hours to days, becoming maximal within 2 weeks.
Optic neuritis - Visual loss is typically associated with ...?
2. Globe tenderness.
3. Eye pain in more than 90% of patients.
--> Pain typically worse with eye movements.
Optic neuritis - Visual field testing demonstrates ...?
A central scotoma (blind spot) associated with decr. visual acuity.
Optic neuritis - Examination of the fundus shows ...?
Unilateral disc swelling when the nerve head is involved, but is NORMAL when the inflammatory process is posterior to the optic disk (retrobulbar neuritis), as is most common in demyelinating disease.
Optic neuritis - The pupils are ...?
EQUAL in size but show less pronounced constriction in response to illumination of the affected eye (relative afferent pupillary defect - Marcus Gunn pupil).
Optic neuritis - Recovery?
Of vision begins in a few weeks and may progress for a year. Normal vision returns in the majority.
Optic neuritis is the 1st manifestation of MS in ...% of cases.
Optic neuritis occurs in ...% of MS patients at some point.
Optic neuritis - Treatment:
IV methylprednisolone, 1g/d for 3 to 5 days,+/- an oral prednisone taper, from 1mg/kg/d over 11 days --> Hasten recovery but does NOT alter the final visual outcome OR the likelihood of developing MS.
Bilateral spontaneous optic neuritis + transverse myelitis occur in ...?
Neuromyelitis optica (NMO) spectrum disorder, formerly called Devic disease.
What is diagnostic of NMO?
Relative afferent pupillary defect (Marcus Gunn pupil):
The involved pupil constricts LESS markedly in response to DIRECT illumination than to illumination of the CONTRALATERAL pupil - Normally the direct response is greater than the consensual response.
Major cause of visual loss beginning in middle age?
Ischemic infarction of the anterior portion of the optic nerve.
--> Nonarteritic anterior ischemic optic neuropathy.
Nonarteritic anterior ischemic optic neuropathy - Visual loss is ...?
Sudden in onset, usually PAINLESS, always MONOCULAR, and without premonitory ocular symptoms.
Nonarteritic anterior ischemic optic neuropathy - The visual deficit is usually ...?
MAXIMAL at onset and frequently subtotal - The pattern of visual loss varies between patients.
Nonarteritic anterior ischemic optic neuropathy - Examination reveals ...?
Ipsilateral disk swelling, often with peripapillary hemorrhages.
Although ischemic optic neuropathy is often assumed to be atherosclerotic in origin ...?
Presentation of symptoms on awakening is a common feature suggesting nocturnal arterial hypotension often from antihypertensive medications.
Patients with anterior ischemic optic neuropathy have ...?
A structurally smaller than normal disk; 15-25% will go on to have the other eye affected within 3 to 5 years.
Nonarteritic anterior ischemic optic neuropathy - Prognosis:
Spontaneous improvement occurs over 6 months.
--> As disk swelling resolves, ophthalmoscopic evaluation shows optic atrophy.
Nonarteritic anterior optic neuropathy - Treatment:
Steroids during the first 2 weeks may enhance recovery (prednisone 80mg daily for 14 days then tapered over a month.
--> Aspirin is ineffective.
Giant cell (temporal) arteritis - Most devastating complication:
Arteritic infarction of the anterior portion of the optic nerve.
Giant cell arteritis - The visual loss is usually ...?
SUDDEN + TOTAL - Transient visual obscurations may precede optic nerve infarction.
Giant cell arteritis - On examination, the optic disk appears ...?
Swollen and pale.