Basics in Neuro ophthalmology

• Introduction• Visual loss & field defects• Diplopia• Supra nuclear ocular motility disorder• Case Vignette• Painful Ophthalmoplegia & Clinical PEARLS• MCQs

Neuro-ophthalmology

• Diseases of the eye and the related neurological apparatus

• Afferent: Optic nerve, retina, chiasm, visual pathways, cortex

• Efferent: Cranial nerve III,IV,VI, ocular muscles, brain stem control centers

Vision loss

Monocular – lesion usually affects retina or optic nerve

Binocular – lesion localized to or beyond the optic chiasm

Retinal involvement – generally a/w ophthalmoscopic abnormalities

Most optic neuropathies involve visual acuity

Spared acuity raise suspicion of Pre-Retinal, Retinal or Retrochiasmal disease

Reduction in the saturation or brightness of colors may be an early sign of optic nerve disease

Look for RAPD in affected eye in unilateral cases Retina or Optic Nerve damage Swinging flashlight test

Visual field defects

Vein

Disc

Macula & Fovea

Artery

Optic cup

Features Primary Secondary Consecutive

Disc Papery white

Grey white Waxy pale

Margins Clear Blurred Normal

Cup Seen well Filled up Present

Lamina cribrosa

Prominent Not seen Not seen

Vessels in & around disc

Minimal Sheathing Attenuated

Peripheral fundus

Normal Changes + Altered Kestenbaum sign

Hemorrhage & exudates Pigmented/ degenerated

Features of optic atrophy

Anatomy and Physiology of ocular motility

BRAINSTEM NUCLEI

OCULOMOTOR TROCHLEAR ABDUCENCS

INTER CONNECTING NEURONS

EXTRA OCULAR MUSCLES

Extra ocular muscles

SR & IR• Primary action - elevation/depression (abducted eye)• Secondary action – torsion, SR - intorter & IR extorter• Tertiary action – adduction

SO & IO• Primary action - torsion, SO intorter & I0 extorter• Secondary action – depression/elevation (adducted eye)• Tertiary action – abduction

MR & LR• Adduction & abduction

DIPLOPIA

It is when more than one image ( two ) of the object of regard are seen simultaneously

1.Is the diplopia monocular or binocular?

J Neurol Neurosurg Psychiatry 2004;75(Suppl IV):iv24–iv31. doi: 10.1136/jnnp.2004.053413

DIPLOPIA

J Neurol Neurosurg Psychiatry 2004;75(Suppl IV):iv24–iv31. doi: 10.1136/jnnp.2004.053413

• Alignment of Images

──horizontal, vertical, or oblique

• Direction of gaze that increases the separation of images

• Onset and progression of the symptoms

• Exacerbating and relieving factors

• Associated symptoms

• Past medical history and family history

DIPLOPIA

EXAMINATION FOR DIPLOPIA

• Complete ophthalmological and orthoptic assessment─ for monocular diplopia

• Identify cause of misalignment in binocular diplopia• Identifying the paretic muscle(s) Subjective Tests ─ Maddox rod and Red lense tests Objective Tests ─ Corneal light reflex tests , Cover tests Three “diplopia rules”(1) Separation of images is greatest in the direction of action of the

weak muscle (2) False image is the more peripheral(3) False image comes from the paretic eye

MADDOX ROD ASSESSMENT

COVER TESTS

• Based on fixation ability Cover/uncover …detect manifest deviation, Exo/eso/hyper/hypotropia Alternate cover ….detect total deviation ( manifest + latent) ….dissociation test …..demonstrate subtle hypertropia• To measure angle of deviation….prism cover test

J Neurol (2014) 261 (Suppl 2):S542–S558

Parks three-step test

Identifying the paretic muscle in vertical diplopia

1) To determine which eye is hypertropic in the primary position RE hypertropic, one of four muscles must be paretic; right eye depressors (right SO & IR) or left eye elevators (left IO & SR )2) To determine whether the hypertropia increases in right orleft horizontal gaze, Worse on left gaze: Rt SO or left SR3) To determine whether the hypertropia is worse on head tilting

to left or right (Bielschowsky test) Worse on head tilt to right….> Rt SOJ Neurol Neurosurg Psychiatry 2004;75(Suppl IV):iv24–iv31. doi: 10.1136/jnnp.2004.053413

Hess Chart•Pictorial and reproducible record of eye movements

•Each eye is plotted in turn for the central fixation spot and targets at 15 and 30 degree eccentricity, respectively

• The smaller field belongs to the paretic eye

•Neurogenic paresis will show the largest under action inthe direction of paretic muscle and the largest over-actionis seen in the contralateral synergist

•Mechanical defects show a compressed field withoutobvious over-action.

Supranuclear Oculomotor Disorders

EYE MOVEMENTS

UNIOCULAR

DUCTION

BINOCULAR

CONJUGATE DYSCONJUGATE

VERSION VERGENCE

CONVERGENCE & DIVERGENCESACCADE, PURSUIT, VOR, OKN

FUNCTIONAL CLASSIFICATION

FUNCTIONAL CLASSIFICATION

JERKYBRINGS TARGET TO

FOVEA

WHEN TARGET IS IN MOTION

WHEN HEAD IS IN MOTION

TRACKING TARGET IN VERTICAL& HORIZONTAL

TO &FRO MOTION IN AP AXIS

BRIEF HEAD MOTION

SUSTAINEDHEAD MOTION

GAZE SHIFTING

GAZE

HOLDING

SACCADE

PURSUIT

VERGENCE

VOR

OKN

saccade“Saquer” – french – to pull Rapidly programmed eye movement, bring target into fovea• Latency-interval b/n appearance of target & onset of saccade- 200

msec• Amplitude & Velocity- Directly proportional to each other 100-700 msec• Accuracy-amount of undershoot/overshoot of target

Types of saccades

VOLUNTARY INVOLUNTARY• Visually guided Reflexive• Predictive Spontaneous• Memory guided Fast phase of nystagmus• Anti saccades

Saccade- mechanical properties

• Combination of 2 mechanical elements-

-pulse & step

• Pulse- (velocity command)- high frequency burst of neural

activity - powerful phasic contraction of EOM - overcomes

resistance of orbital tissue & inertia of globe

• Step- (position command)-sustained contraction arising from a

constant level of neural activity- keeps eye in the new position

• Integration of velocity coded into position code by neural

integrators : NPH & MVN, INC

• Premotor burst neurons: EBN : excite pulse mechanism before

saccade

• IBN: Inhibit pulse in antagonist muscles & help in moving with

contacting muscles

• Omnipause neurons: Inhibit all burst neurons, check

unwanted firing EBN IBN Neural

integratorsOmni pause

Horizontal PPRF Medullary Reticular formation

NPH & MVN Nucleus RapheInterpositus

Vertical Ri MLF Medullary Reticular formation

INC Nucleus RapheInterpositus

SACCADIC PATHWAY

DeJong's The Neurologic Examination

Abnormal saccades• Saccadic dysmetria: Cerebellar lesions

• Anti saccades: Frontal lobe/connection to basal ganglia

• Saccadic intrusions- interfere with macular fixation

- square wave jerks – spontaneous small amplitude paired saccades

with inter saccadic latency 150-200ms …..PSP, MSA, cerebellar disease

-macro square wave jerks – larger amplitude(10-40) & shorter

latency(80ms)….MS, OPCA

-ocular flutter- to & fro horizontal saccades without inter saccadic

interval… MS, cerebellar disease

-Opsoclonus(saccado mania)- conjugate involuntary large amplitude

multidirectional saccades..brainstem / cerebellar disease/

paraneoplastic

Smooth pursuit

• Slow conjugate eye movement

• To track relatively slow moving targets

(no faster than 30° per sec)

• Voluntary or involuntary

• To keep image of a moving object at fovea

• Mediated by parieto-occipito-temporal-mesencephalic pathway

• Ipsilateral control

• Latency > 125m sec

• Can track target moving up to 30˚ – 40˚/sec or 2Hz

Retinal image movement

Lateral geniculate

nucleus

Striate cortex

MT, MST, posterior parietal cortex

First descussation of horizontal pursuit pathway

Second descussation of horizontal pursuit pathway

Fastigial nucleus, medial vestibular nucleus

Cerebellar cortex

Smooth pursuit

movements

Pontine nuclei

Ocular motor nuclei (3,4, and 6)

FEF, SEF

Nucleus of optic tract pathway

Pathway for horizontal smooth pursuit

Retinal image movement

Lateral geniculate

nucleus

Striate cortex

MT, MST, posterior parietal cortex

First descussation of horizontal pursuit pathway

Second descussation of horizontal pursuit pathway

Y group neurons

DentateNucleus

cerebellum

VerticalSmooth pursuit

movements

Nucleus reticularis Tegmenti

pontis

Ocular motor nuclei (3,4, and 6)

FEF, SEF

Nucleus of optic tract pathway

Ipsilateral cortical control

Pathway for vertical smooth pursuit

Lesions –smooth pursuit

• Frontal lesions – impair I/L pursuit

• Parietal lesions – decrease amplitude & velocity of I/L pursuit

• B/L occipital – abolish smooth pursuit

• MLF – vertical pursuit

• Upward pursuit – decussate in posterior commissure

• Downward pursuit – INC –

• Role of Cerebellum –

*dorsal vermis & fastigial nucleus …onset of pursuit

*paraflocculus & flocculus …sustain pursuit response

VOR

• Conjugate eye movement, moves eye equal & opposite to head

movement

• Velocity of 800 degree/sec within a brief reaction time of 15ms

• Two types: horizontal, vertical & torsional VOR

• Function: Fix retinal images during head movements

• VOR cancellation: Normal component: inactivates VOR when target

moving in same direction of head

• Semi circular canal for angular rotation

• The Otolith organ for linear acceleration

• Reflex starts by movement of head> stimulation of

vestibular sensors> VOR circuitry in brain stem> eye

velocity command

• Head rotation to right> stimulation of ipsilateral

HC>activation of right MR & left LR> eye rotates to

left

• Down ward head acceleration> stimulates both AC

• Upward head acceleration> both PC

Optokinetic reflex

• OKN : reflexive oscillation of eyes alternating slow & quick

phases, produced by movement of visual field

• Stabilizes eye during tracking of large moving visual scene

• Responsible for sense of illusionary motion while sitting in

a vehicle

• Pathway : Retina>AOT> CTT>Inferior

olive>cerebellum(which receive vestibular fibres)

Nuclear Inter nuclear Lesions

• Abducens nuclear level: Lateral gaze palsy while looking to

ipsilateral direction, VOR also affected

• PPRF: Ipsilateral horizontal saccadic palsy, VOR not affected

• MLF: Inter nuclear ophtalmoplegia

• PPRF+ MLF= One& half syndrome, VOR spared

• Abducens complex+ MLF= One & half syndrome , VOR affected

• PPRF+MLF+facial nerve nuclei: 8&1/2 syndrome

• PPRF+MLF+b/l facial nerve nuclei: 15&1/2 syndrome

Inter nuclear ophthalmoplegia

• Due to a lesion of MLF in either pons or midbrain

• Continuity b/w abducens and contra lateral oculomotor nuclei via MLF

lost

• Type 1 INO: Lesion in midbrain near convergence area, on conjugate

gaze medial rectii are affected both sides

Normal abduction, convergence also affected

• Type II INO: Lesion midway b/w 3rd & 6th nerve nuclei

Adduction is affected on both sides with normal abduction Convergence

spared

If INO is bilateral

• abduction saccades also may be slow

• Upward beating and torsional nystagmus

• Type III INO: Lesion is in relay to 6th CN nuclei

Abduction is affected in both eyes with relatively

preserved adducion

Skew Deviation

• Common supra nuclear gaze palsy, of vertical type

• Interruptions in the pathway between VN & vertical oculo motor

CN nucleus

• When a person tilts head, eye in downward direction moves

oppositely

• If brainstem lesions below the level of decussation> eye on side of

lesion will be lower eye

• If lesion above level of decussation> eye on side of lesion will be

at higher level

• Ocular tilt reaction: Pathological head tilt, inappropriate

torsional rotation & skew deviation

• Head & superior poles of both eye rotate toward lower

eye

• The higher eye is incyclotorted

• Skew deviation may occur in combination with INO

Dorsal Mid brain syndrome

• Lesions involving posterior commissure fibers projected from INC

• Occurs in dorsal midbrain region, pineal gland lesions and hydrocephalus

• Components:

1. Impaired vertical gaze

2. Square wave jerks

3. Vergence dysfunction

4. Skew deviation

5. Convergence retraction nystagmus

6. Lid retraction

7. Light near pupil dissociation

CASE VIGNETTE• 75 year old male

• C/o decreased sensation over right face along with right sided

ptosis X 15 days

• Loss of vision in right eye X 12 days

• O/E Right sided ptosis & complete ophthalmoplegia

• Absence of light perception & pupillary reaction right side

• Decreased pain perception along right V1&V2

Clinical possibility ???

Painful Ophthalmoplegia

• Orbital pain + any combination of I/L ocular motor

palsies, oculo sympathetic paralysis or sensory

distribution in V1&V2 distribution

• Localization: orbit/orbital apex/superior orbital

fissure/cavernous sinus/subarachnoid

space/mesencephalon

SITES STRUCTURES INVOLVED

MESENCEPHALON 3RD OR 4TH NERVE

SUBARACHNOID SPACE 3RD, 4TH OR 6TH IN VARYING COMBINATIONS

PARASELLAR REGION 2ND, 3RD, 4TH & 5TH NERVE IN VARYING COMBINATION

POSTERIOR CAVERNOUS SINUS 3RD, 4TH , 6TH AND ALL DIVISIONS OF 5TH NERVE

MIDDLE CAVERNOUS SINUS 3RD, 4TH, 6TH AND 1&2 DIVISIONS OF 5TH NERVE

ANTERIOR CAVERNOUS SINUS 3RD , 4TH, 6TH AND FIRST DIVISION OF 5TH

HORNERS SYNDROME ACCOMPANY CAVERNOUS SINUS PATHOLOGY AT ANY SITE

SITES LOCALIZATION

ORBITAL FISSURE 3RD, 4TH, 6TH & FIRST DIVISION OF 5TH NERVE IN VARYING COMBINATION

ORBIT 2ND , 3RD, 4TH, 6TH AND 1ST DIVISION OF 5TH

UNKNOWN ANY OCULAR MOTOR NERVE ALONE OR IN COMBINATION

DIABETES, MIGRAINE, VASCULITIS

Clinical Pearls

• Nuclear lesions of 3rd nerve result in b/l ptosis

• Nuclear lesion of 3rd nerve often result in

weakness of superior recti b/l

• Fascicular 3rd nerve palsy in brainstem associated

with contra lateral long tract signs

• Isolated 3rd nerve palsy : Most likeley lesion within

subarachnoid space, compressive/ischemic

•The compressive lesions most often affect pupillomotor fibres

• Exception: Lesion which press 3rd nerve from below

•Combination of oculomotor paresis and sympathetic denervation

almost pathagnomonic of cavernous sinus lesion

•Maxillary division of 5th nerve escapes damage at superior orbital

fissure

•Isolated involvement of either superior or inferior division of 3rd

nerve strongly suggest orbital lesion….. BUT

•4th CN palsy : Vertical diplopia, head tilt to normal side

•Combination of 6th & 12th in Nasopharyngeal Ca & Clival tumor