PARALYTIC STRABISMUS

PARALYTIC STRABISMUSPARALYTIC STRABISMUS

Assist.Prof. Dr.Vildan ÖztürkOphthalmologyYeditepe University Hospital

STRABISMUSSTRABISMUS Strabismus involves deviation of the

alignment of one eye in relation to the other.

1. Non-paralytic strabismus2. Paralytic strabismus

concomitant strabismus; – due to faulty insertion of the eye muscles,

resulting in the same amount of deviation regardless of the direction of the gaze

nonconcomitant strabismus; – in which the amount of deviation of the

squinting eye varies according to the direction of gaze

Strabismus=Squint, Wandering Strabismus=Squint, Wandering eyeeye

Esotropia=Crossed eyes Esotropia=Crossed eyes Exotropia=WalleyeExotropia=Walleye

ANATOMY

Anatomic axis Visual (optical) axisKappa angle:

ANATOMY OF EXTRAOCULAR ANATOMY OF EXTRAOCULAR MUSCLES:MUSCLES:

The lateral and medial The lateral and medial walls of the orbit make an walls of the orbit make an angle of 45 degrees with angle of 45 degrees with each other.each other.

In In primary positionprimary position the the optical axis forms an optical axis forms an angle of 22.5 degrees angle of 22.5 degrees with the orbit.with the orbit.

ANATOMY OF EXTRAOCULAR ANATOMY OF EXTRAOCULAR MUSCLES:MUSCLES:

Primary actionPrimary action of the muscle is its major effect when of the muscle is its major effect when the eye is in primary positionthe eye is in primary position

Subsidiary actionsSubsidiary actions are the additional effects of the are the additional effects of the position of the eyeposition of the eye

Listing planeListing plane is an imaginary frontal equatorial plane is an imaginary frontal equatorial plane passing through the center of rotation of globe. passing through the center of rotation of globe. -The globe rotates left and right around the vertical Y -The globe rotates left and right around the vertical Y axisaxis

-The globe moves up and down around the horizontal X -The globe moves up and down around the horizontal X axis.axis.-Torsional movements occur around the Z axis which -Torsional movements occur around the Z axis which traverses the globe from front to back.traverses the globe from front to back.

Z axis

X azis

Y axis

EYE MOVEMENTSEYE MOVEMENTS

DuctionsDuctions are monocular eye movements are monocular eye movements around the axis of Fick. (X, Y, Z) around the axis of Fick. (X, Y, Z) AAdductiondduction; ; mmovement of the eye nasally ovement of the eye nasally AAbductionbduction;; is temporal movement is temporal movement SSupraductionupraduction; ; eelevation levation IInfraductionnfraduction;; depression of depression of the eyethe eyeIncycloductionIncycloduction ( (intorsionintorsion)); ; nasal rotation of the nasal rotation of the vertical meridianvertical meridianEExcycloductionxcycloduction ( (extorsionextorsion)); ; temporal rotation temporal rotation of the vertical meridian.of the vertical meridian.

SIX CARDINAL POSITIONS OF SIX CARDINAL POSITIONS OF GAZEGAZE

Up / rightUp / right

Up / leftUp / left

RightRight

LeftLeft

Down / rightDown / right

Down / leftDown / left

HORIZONTAL RECTUS HORIZONTAL RECTUS MUSCLESMUSCLES::

--Medial rectusMedial rectus: it’s action is : it’s action is

adductionadduction --Lateral rectusLateral rectus: it’s sole action is : it’s sole action is

abduction.abduction.

VERTICAL RECTUS MUSCLESVERTICAL RECTUS MUSCLES

Superior rectusSuperior rectus:: primary action is elevationprimary action is elevation secondary actions are adduction and intorsionsecondary actions are adduction and intorsion

Inferior rectusInferior rectus: : primary action is primary action is depressiondepression secondary actions are adduction and secondary actions are adduction and

extorsionextorsion

OBLIQUE MUSCLESOBLIQUE MUSCLES

Superior Superior oblique oblique musclemuscle – incyclotorsion. incyclotorsion. – depressiondepression– abductionabduction

IInferior oblique musclenferior oblique muscle – excyclotorsionexcyclotorsion– elevationelevation– abductionabduction

Muscle Innervation Primary action

Secondary action

Tertiary action

Medial rectus CN III Adduction -- --

Superior rectus

CN III Elevation Intortion Adduction

Inferior rectus CN III Depression Extortion Adduction

Inferior oblique CN III Extorsion Elevation Abduction

Superior oblique

CN IV Intorsion Depression Abduction

Lateral rectus CN VI Abduction -- --

Tillaux’nun Spirali

LAWS OF OCULAR MOTILITYLAWS OF OCULAR MOTILITYAAgonistgonist : t: the primary muscle that moves an eye in a he primary muscle that moves an eye in a given direction given direction

SSynergistynergist; ; muscle in the same eye that moves the muscle in the same eye that moves the eye in the same direction as the agonist eye in the same direction as the agonist

AAntagonistntagonist; ; muscle in the same eye that moves the muscle in the same eye that moves the eye in the opposite direction of the agonist eye in the opposite direction of the agonist muscle muscle

Sherrington Sherrington LLawaw, increased innervation to any , increased innervation to any muscle (agonist) is accompanied by a corresponding muscle (agonist) is accompanied by a corresponding decrease in innervation to its antagonistsdecrease in innervation to its antagonists. .

LAWS OF OCULAR MOTILITYLAWS OF OCULAR MOTILITY

Yoke musclesYoke muscles – PPrimary muscles in each eye that accomplish rimary muscles in each eye that accomplish

a given versiona given version.. – Each extra ocular muscle has a yoke muscle Each extra ocular muscle has a yoke muscle

in the opposite eye to accomplish versions in the opposite eye to accomplish versions into each gaze positioninto each gaze position..

Herring Herring LLawaw;; – YYoke muscles receive equal and oke muscles receive equal and

simultaneous innervation; simultaneous innervation; – MMagnitude is determined by the fixating eye. agnitude is determined by the fixating eye.

BBIINOCULAR EYE MOVEMENTSNOCULAR EYE MOVEMENTS

CConjugate (versionsonjugate (versions)) are movements are movements of both eyes in the same direction of both eyes in the same direction

--DextroversionDextroversion is movement of both eyes is movement of both eyes to the right, to the right,

--LLevoversionevoversion is movement of both eyes is movement of both eyes to the left. to the left.

--SupraversionSupraversion; ; elevationelevation of both eyes, of both eyes,

--InfraversionInfraversion; ; depression of both eyes, depression of both eyes,

BİNOCULAR EYE MOVEMENTSBİNOCULAR EYE MOVEMENTS

DDisconjugate (vergencesisconjugate (vergences)) are are movements of the eyes in opposite movements of the eyes in opposite directions. directions.

--ConvergenceConvergence is movement of both eyes is movement of both eyes nasallynasally

--DDivergenceivergence is movement of both eyes is movement of both eyes temporally. temporally.

--Vertical vergenceVertical vergence movements also may movements also may occuroccur..

TTYPES OF STRABYPES OF STRABIISMUSSMUS

EsotropiaEsotropia is is inward turning inward turning

ExotropiaExotropia is is outward turninoutward turningg

HypertropiaHypertropia isis upward turning upward turning

HypotropiaHypotropia isis downward turning of downward turning of

the eyethe eye..

ESOTROPIAESOTROPIA

EXOTROPIAEXOTROPIA

HYPERTROPIAHYPERTROPIA

HYPOTROPIAHYPOTROPIA

HIRSCHBERG TEST

DIPLOPIADIPLOPIA

Simultaneous Simultaneous appreciation of two appreciation of two images of one object. images of one object.

It results from a failure It results from a failure to maintain binocular to maintain binocular vision.vision.

Binocular, monocular, Binocular, monocular, physiologicalphysiological

MUSCLE MUSCLE IINNERVATNNERVATIIONSONS

medial rectus (MR)—cranial nerve III medial rectus (MR)—cranial nerve III

lateral rectus (LR)—cranial nerve VI lateral rectus (LR)—cranial nerve VI

superior rectus (SR)—cranial nerve III superior rectus (SR)—cranial nerve III

inferior rectus (IR)—cranial nerve III inferior rectus (IR)—cranial nerve III

superior oblique (SO)—cranial nerve IV superior oblique (SO)—cranial nerve IV

inferior oblique (IO)—cranial nerve IIIinferior oblique (IO)—cranial nerve III

Extra ocular muscle paralysisExtra ocular muscle paralysis resulting resulting from destructive lesions in one or all of from destructive lesions in one or all of these cranial nerves results in failure of these cranial nerves results in failure of one or both eyes to rotate in concert with one or both eyes to rotate in concert with the other eye. the other eye.

(LR6SO4)3

OCULAR MOTOR NERVE PALSIES

1. Third nerve

2. Fourth nerve

3. Sixth nerve

OCULOMOTOR (III.) NERVE OCULOMOTOR (III.) NERVE PALSYPALSY

• The oculomotor nerve innervatesThe oculomotor nerve innervates• superior rectus,superior rectus, inferior rectus, medial rectus, inferior rectus, medial rectus, • inferior oblique, inferior oblique, • levator palpebrae, levator palpebrae, • ciliary muscle ciliary muscle • iris sphincter. iris sphincter.

OCULOMOTOR (III.) NERVE PALSYOCULOMOTOR (III.) NERVE PALSY

Anatomy of third nerveOculomotor nucleus

Pituitary gland

Carotid artery

Cavernous sinus

III nerveClivus

Basilar artery

Post cerebral artery

Red nucleus

Pons

Nuclear portionNuclear portion

Fascicular portionFascicular portion – intraparenchymal intraparenchymal mmidbrain idbrain portionportion– subarachnoid portionsubarachnoid portion – cavernous sinus portioncavernous sinus portion – orbital portionorbital portion

ANATOMYANATOMY

The The pupillomotor and ciliary musclepupillomotor and ciliary muscle neurons neurons derive from the Edinger-Westphal derive from the Edinger-Westphal subnucleus, which is in the midline in the subnucleus, which is in the midline in the most rostral and anterior part of the most rostral and anterior part of the oculomotor nerve nucleus. oculomotor nerve nucleus.

These autonomic pathways are all These autonomic pathways are all ipsilateral or uncrossedipsilateral or uncrossed


Applied anatomy of pupillomotor nerve fibresBlood vessels on pia mater supply surface of the nerve including pupillary

fibres ( damaged by compressive lesions )

Vasa nervorum supply partof nerve but not pupillaryfibres ( damaged by medicallesions )

Pupillary fibres lie dorsal and peripheral

ETIOLOGYETIOLOGYA- A- Pupil involvingPupil involving

More commonMore common: Aneurysm ( particularly a post. : Aneurysm ( particularly a post. communicating artery aneurysm)communicating artery aneurysm)

Less commonLess common: Ischemic microvascular disease ( DM : Ischemic microvascular disease ( DM or HT), tumour, trauma, congenitalor HT), tumour, trauma, congenital

Rare: Rare: Uncal herniation, cavernous sinus mass lesion, Uncal herniation, cavernous sinus mass lesion, pituatery apoplexy, orbital disease, herpes zoster, pituatery apoplexy, orbital disease, herpes zoster, leukemia, in children ophthalmoplegic migraine leukemia, in children ophthalmoplegic migraine


ETIOLOGYETIOLOGY

B- B- PPupil–sparingupil–sparing: Ischemic microvascular : Ischemic microvascular disease; rarely cavernous sinus syndrome, disease; rarely cavernous sinus syndrome, giant cell arteritis (GCA)giant cell arteritis (GCA)

C- C- Relative pupil-sparingRelative pupil-sparing: Ischemic microvascular : Ischemic microvascular disease; less likely aneurysmdisease; less likely aneurysm


Etiology

Important causes of isolated third nerve palsyIdiopathic - about 25%

Vascular disease - hypertension, diabetes

Posterior communicating aneurysmTrauma

Extraduralhaematoma

Prolapsingtemporallobe

Edge oftentorium

Aneurysm

Chiasm

Third nerve

Posterior cerebralartery

Midbrainpushedacross

ETİOLOGYETİOLOGY

Nuclear Nuclear and fascicular midbrain and fascicular midbrain portionportion– InfarctionInfarction– HemorrhageHemorrhage– NeoplasmNeoplasm– AbscessAbscess


ETIOLOGYETIOLOGY– Fascicular midbrain portionFascicular midbrain portion infarcts infarcts

Benedikt syndromeBenedikt syndrome – upper mid brain includes upper mid brain includes – ipsilateral ipsilateral third cranial nerve palsythird cranial nerve palsy– contracontralateral flapping hand tremorlateral flapping hand tremor – ataxiaataxia

Weber syndromeWeber syndrome – slightly more ventral lesion at the level of the third slightly more ventral lesion at the level of the third

cranial nerve fascicles in the mid braincranial nerve fascicles in the mid brain– ipsilateral third cranial nerve palsyipsilateral third cranial nerve palsy– contralateral hemiplegia or hemiparesis contralateral hemiplegia or hemiparesis


ETIOLOGYETIOLOGY

Fascicular subarachnoid portionFascicular subarachnoid portion– AneurysmAneurysm– Infectious meningitis - Bacterial, Infectious meningitis - Bacterial,

fungal/parasitic, viralfungal/parasitic, viral– Meningeal infiltrativeMeningeal infiltrative– CarcinomatousCarcinomatous // lymphomatouslymphomatous // leukemic leukemic

infiltration, granulomatous inflammation infiltration, granulomatous inflammation (sarcoidosis, lymphomatoid granulomatosis, (sarcoidosis, lymphomatoid granulomatosis, Wegener granulomatosis)Wegener granulomatosis)


ETIOLOGYETIOLOGYFascicular cavernous sinus portionFascicular cavernous sinus portion– Tumor - Pituitary adenoma, meningioma, Tumor - Pituitary adenoma, meningioma,

craniopharyngioma, metastatic carcinoma craniopharyngioma, metastatic carcinoma – Vascular Vascular – Giant intracavernous aneurysmGiant intracavernous aneurysm– Carotid artery-cavernous sinus fistula Carotid artery-cavernous sinus fistula – Carotid dural branch-cavernous sinus fistula Carotid dural branch-cavernous sinus fistula – Cavernous sinus thrombosis Cavernous sinus thrombosis – Ischemia from microvascular disease in vasa Ischemia from microvascular disease in vasa

nervosa nervosa – Inflammatory - Tolosa-Hunt syndrome (idiopathic Inflammatory - Tolosa-Hunt syndrome (idiopathic

or granulomatous inflammation)or granulomatous inflammation)


ETIOLOGYETIOLOGY

Fascicular orbital portionFascicular orbital portion– InflammatoryInflammatory, o, orbital inflammatory rbital inflammatory

pseudotumor, orbital myositis pseudotumor, orbital myositis – Endocrine (thyroid orbitopathy) Endocrine (thyroid orbitopathy) – Tumor (hemangioma, lymphangioma, Tumor (hemangioma, lymphangioma,

meningioma)meningioma)


FREQUENCYFREQUENCY

%30 of paralytic strabismus%30 of paralytic strabismus

MORTALİTYMORTALİTY // MORBİDİTY MORBİDİTY subarachnoid hemorrhage from berry subarachnoid hemorrhage from berry aneurysm of the posterior communicating aneurysm of the posterior communicating arteryartery

meningitis or meningeal infiltrative meningitis or meningeal infiltrative disorders, both infectious and neoplasticdisorders, both infectious and neoplastic


SYMPTOMSSYMPTOMS

Binocular diplopia Binocular diplopia

PtosisPtosis

Mydriasis Mydriasis

With or without painWith or without pain


Signs of right third nerve palsy

• Ptosis, mydriasis and cycloplegia

• Abduction in primary

position

• Limited depression • Limited adduction

• Normal abduction

• Limited elevation

• Intorsion on attempted downgaze

CRITICAL SIGNSCRITICAL SIGNSExternal ophthalmoplegia ( motility impaired)External ophthalmoplegia ( motility impaired)

1-Complete palsy: Limitation of ocular 1-Complete palsy: Limitation of ocular movement in all fields of gaze except movement in all fields of gaze except temporallytemporally

2-Incomplete palsy:partial limitation of ocular 2-Incomplete palsy:partial limitation of ocular movement movement

3-Superior division palsy: Ptosis and inability to 3-Superior division palsy: Ptosis and inability to look uplook up

4-Inferior division palsy: Inability to look nasally 4-Inferior division palsy: Inability to look nasally or inferiorly: pupil is involvedor inferiorly: pupil is involved


CRITICAL SIGNSCRITICAL SIGNS

Internal ophthalmoplegia ( Pupil reaction Internal ophthalmoplegia ( Pupil reaction impaired)impaired)

1-Pupil involving: A fixed, dilated minimally 1-Pupil involving: A fixed, dilated minimally reactive pupil.reactive pupil.

2-Relative pupil sparing: Pupil partially 2-Relative pupil sparing: Pupil partially dilated and sluggishly reactive to pupildilated and sluggishly reactive to pupil


Hess chart of right third nerve palsy

• Contraction of right chart and expansion of left• Right chart - underactions of all muscles except lateral rectus and superior oblique• Left chart - overactions of all muscles except medial rectus and inferior oblique

WORKUPWORKUP

HistoryHistoryComplete ocular examination, Hess chartComplete ocular examination, Hess chartFull neurologic examinationFull neurologic examinationInternal medicine examinationInternal medicine examinationImaging studyImaging study

MRIMRICTCTCerebral angiographCerebral angiographyy


WORKWORKUUPP

Lumbar punctureLumbar puncture

HistologicHistological al ffindingsindings

CBCCBC

ESRESR


TREATMENTTREATMENT

Treat the underlying abnormalityTreat the underlying abnormality

If diplopia, an occlusion patch ( not for If diplopia, an occlusion patch ( not for children) or prismschildren) or prisms

NSAIDs commonly are used to treat the NSAIDs commonly are used to treat the pain in ischemic third cranial nerve palsy.pain in ischemic third cranial nerve palsy.

Surgery may be performed after 6 monthsSurgery may be performed after 6 months

Botulinum toxin injectionsBotulinum toxin injections


FOLLOW UPFOLLOW UP

Pupil sparing: Pupil sparing: Observe daily for 5 to 7 daysObserve daily for 5 to 7 days

Recheck every 4 to 6 weeksRecheck every 4 to 6 weeks

If the function is not regained in 3 months, refer to If the function is not regained in 3 months, refer to the internist+MRI the internist+MRI

Pupil involvingPupil involvingIf imaging and angiography are negative, follow If imaging and angiography are negative, follow as pupil sparing caseas pupil sparing case


MedicalMedical // Legal Pitfalls:Legal Pitfalls:

– The most common misadventure is failing to The most common misadventure is failing to undertake adequate workup for aneurysmundertake adequate workup for aneurysm in a in a patient with third cranial nerve palsy.patient with third cranial nerve palsy.

– On the other hand, On the other hand, performing cerebral performing cerebral angiography on patients with ischemic third angiography on patients with ischemic third cranial nerve palsy poses distinct riskscranial nerve palsy poses distinct risks for for these patients, many of whom have severe these patients, many of whom have severe atherosclerosis.atherosclerosis.


Trochlear (IV.) nerve palsyTrochlear (IV.) nerve palsy

In 1935, Bielschowsky correctly noted that In 1935, Bielschowsky correctly noted that trochlear nerve palsy was the trochlear nerve palsy was the most most common cause of vertical diplopiacommon cause of vertical diplopia and and introduced his classic head-tilt test. introduced his classic head-tilt test.

With greater clinical interest, the number With greater clinical interest, the number of identified fourth nerve palsies has of identified fourth nerve palsies has increased. increased.


The fourth cranial nerve innervates The fourth cranial nerve innervates superior oblique muscle superior oblique muscle – intorts intorts – depresses depresses – abducts the globe. abducts the globe.

Can be congenital or acquired, unilateral Can be congenital or acquired, unilateral or bilateral.or bilateral.

SO-LIDSO-LID

Anatomy of fourth nerve

• Only cranial nerve to emerge dorsally• Crossed cranial nerve• Very long and slender

Internal carotid artery

Postr. communicating artery

IIIVI

Postr.cerebral arterySupr.cerebellar artery

Basilar arteryIV

FrequencyFrequency

% 11 of all paralytic strabismus% 11 of all paralytic strabismus


PathophysiologyPathophysiology

Congenital Congenital lesions are frequent. Head lesions are frequent. Head posture is gained.posture is gained.– secondary to dysgenesis of fourth nerve secondary to dysgenesis of fourth nerve

nucleus nucleus – abnormalities of peripheral nerve abnormalities of peripheral nerve – abnormal superior oblique muscle or tendonabnormal superior oblique muscle or tendon


PathophysiologyPathophysiology

AcquiredAcquired – The long course of the trochlear nerve makes The long course of the trochlear nerve makes

it especially susceptible to injury in it especially susceptible to injury in association with severe association with severe head head traumatrauma. . Contrecoup forces can compress the nerve Contrecoup forces can compress the nerve against the rigid tentoriumagainst the rigid tentorium

– Vascular lesionsVascular lesions are common.are common.


Etiology:Etiology:

Idiopathic, Idiopathic,

Severe head trauma,Severe head trauma,

Microvasculopathy secondary to diabetes, Microvasculopathy secondary to diabetes, atherosclerosis, or hypertension atherosclerosis, or hypertension

There are rare reports of thyroid There are rare reports of thyroid ophthalmopathy and myasthenia gravis ophthalmopathy and myasthenia gravis presenting as isolated fourth nerve palsy. presenting as isolated fourth nerve palsy.


EtiologyEtiology

Tumor, aneurysm, multiple sclerosis, or Tumor, aneurysm, multiple sclerosis, or iatrogenic injury iatrogenic injury

After cataract surgery. (Patients with underlying, After cataract surgery. (Patients with underlying, well-controlled, and asymptomatic fourth nerve well-controlled, and asymptomatic fourth nerve palsy may decompensate gradually as they lose palsy may decompensate gradually as they lose binocular function resulting from cataract. binocular function resulting from cataract. Following restoration of good vision, these Following restoration of good vision, these patients become aware of diplopia.)patients become aware of diplopia.)


SYMPTOMSSYMPTOMS

Binocular vertical diplopiaBinocular vertical diplopia

Reading diffucultyReading diffuculty

Sensation that objects appear tiltedSensation that objects appear tilted

May be asymptomaticMay be asymptomatic


Signs of right fourth nerve palsy

• Right overaction on left gaze

• Right underaction on depression in adduction • Vertical diplopia

• Right hyperdeviation in primary position when left eye fixating• Excyclotorsion

SIGNSSIGNS

Head tilt toward to contralateral shoulder to Head tilt toward to contralateral shoulder to eliminate diplopia. (eliminate diplopia. (Bielschowsky testBielschowsky test ) )


Positive Bielschowsky test in right fourth nerve palsy

Absence of right hyperdeviation on contralateral head tilt

Increase in right hyperdeviation on ipsilateral head tilt

THREE-STEP TESTTHREE-STEP TEST

Each step reduces by half the number of possible Each step reduces by half the number of possible affected muscles until only 1 remains. affected muscles until only 1 remains.

First step is to identify the First step is to identify the hypertropic eyehypertropic eye in primary in primary gaze. gaze. – This implicates depressors of hypertropic eye or elevators of This implicates depressors of hypertropic eye or elevators of

hypotropic eye. hypotropic eye.

Second step is to ascertain if hypertropia is worse on Second step is to ascertain if hypertropia is worse on left left gaze or right gazegaze or right gaze. . – This will identify 4 muscles that act in that direction of gaze. This will identify 4 muscles that act in that direction of gaze.

Third step is to determine if hypertropia is worse on Third step is to determine if hypertropia is worse on right right head tilt or left head tilt.head tilt or left head tilt.


WORKUPWORKUP

HistoryHistory

Old photographsOld photographs

ESR, fasting blood sugar, blood pressureESR, fasting blood sugar, blood pressure

MRI, CTMRI, CT

Three step testThree step test

Hess chartHess chart


Hess chart of right fourth nerve palsy

• No significant difference in chart size• Upward deviation of right fixation spot on inner chart (hypertropia)• Downward deviation of left fixation spot on inner chart• Right chart - underaction of superior oblique and overaction of inferior oblique• Left chart - overaction of inferior rectus and underaction of superior rectus

TREATMENTTREATMENT

Treat the underying causeTreat the underying causeOcclusion patch or prism in spectacles to relieve Occlusion patch or prism in spectacles to relieve the diplopiathe diplopiaBotulinum toxin also has been studied in Botulinum toxin also has been studied in treatment of fourth nerve palsy. It is a treatment of fourth nerve palsy. It is a neuromuscular agent that acts presynaptically to neuromuscular agent that acts presynaptically to block neurotransmitter release and results in block neurotransmitter release and results in muscle weakening. muscle weakening. IIt may be used best to t may be used best to correct residual deviation after strabismus correct residual deviation after strabismus surgery to delay or avoid further surgery. surgery to delay or avoid further surgery. If head tilt and severe diplopia for reading insists If head tilt and severe diplopia for reading insists after 6 months, surgery may be performedafter 6 months, surgery may be performed


FOLLOW UPFOLLOW UP

Congenital IV. Nerve palsy; routineCongenital IV. Nerve palsy; routine

Acquired IV. Nerve palsy;Acquired IV. Nerve palsy;Follow of the underlying causeFollow of the underlying cause

If work up negative, follow monthly up to 6 month, If work up negative, follow monthly up to 6 month, then surgery may be neededthen surgery may be needed

ABABDUCENS DUCENS (VI.) (VI.) NERVE PALSYNERVE PALSY

IInnervates the ipsilateral lateral rectus nnervates the ipsilateral lateral rectus which functions to abduct the ipsilateral which functions to abduct the ipsilateral eye. eye.

It has the longest subarachnoid course of It has the longest subarachnoid course of all the cranial nerves; therefore, its all the cranial nerves; therefore, its syndromes are similar to those of the syndromes are similar to those of the fourth nerve because of their long fourth nerve because of their long intracranial courses. intracranial courses.

Anatomy of sixth nerve

Basilar artery

Pituitary gland

Carotid artery

Cavernous sinus

VI nerve

Petroclinoidligament

Clivus

Pyramidal tract

Vestibularnucleus

Mediallemniscus

4th ventricle

ETIOLOGYETIOLOGY YYounger patientsounger patients; p; postviral syndromeostviral syndrome, , trauma, increased intracranial pressure, trauma, increased intracranial pressure, pontine glioma, Gradenigo’s syndromepontine glioma, Gradenigo’s syndromeAAdult populationdult population; vasculopathic, increased ; vasculopathic, increased intracranial pressure, GCA, cavernous intracranial pressure, GCA, cavernous sinus mass sinus mass

FREQUENCYFREQUENCYThe mostThe most commonly affected of the ocular commonly affected of the ocular motor nervesmotor nerves; ; % 45 of paralytic strabismus% 45 of paralytic strabismus


Important causes of isolated sixth nerve palsyVascular - hypertension, diabetes

Acoustic neuromaRaised intracranial pressure

Dilated ventricles

Petroustip

Brainstem pushed downwards

Mortality/Morbidity:Mortality/Morbidity:

A A young patientyoung patient should have aggressive should have aggressive workup because of the greater likelihood workup because of the greater likelihood of a of a neoplasmneoplasm causing the palsy. causing the palsy.

Patients Patients older than 40 yearsolder than 40 years require a less require a less aggressive workup because of the greater aggressive workup because of the greater likelihood of the etiology being more likelihood of the etiology being more benign in naturebenign in nature eg eg ischemic ischemic mononeuropathy mononeuropathy


SYMPTOMSSYMPTOMS

Patients usually present with horizontal Patients usually present with horizontal diplopiadiplopia( side by side image)( side by side image) and an and an esotropia in primary gaze. Esotropiaesotropia in primary gaze. Esotropia

Head-turnHead-turn

Recent right sixth nerve palsy

Right esotropia in primary position due to unopposed action of right medial rectus

Marked limitation of right Abduction due to right lateral rectus weakness

Old right sixth nerve palsy

Straight in primary position due to partial recovery

Limitation of right abduction and horizontal diplopia

Normal right adduction

WORKUPWORKUP

AdultsAdultsHistoryHistory

Neurologic and ophthalmologic examination Neurologic and ophthalmologic examination

Blood pressure , fasting blood sugar, ESRBlood pressure , fasting blood sugar, ESR

MRI of the brainMRI of the brain

Children Children HistoryHistory

Neurologic and ophthalmologic examination Neurologic and ophthalmologic examination

Otoscopic examinationOtoscopic examination

MRIMRI

Hess chart of recent right sixth nerve palsy

• Contraction of right chart and expansion of left• Right chart - marked underaction of lateral rectus and mild overaction of medial rectus• Left chart - marked overaction of medial rectus

TREATMENTTREATMENT

Underlying cause treatedUnderlying cause treated

Occlusion patch or prism in spectacles for Occlusion patch or prism in spectacles for adultsadults

Strabismus surgery for stable deviations Strabismus surgery for stable deviations that persist more than 6 monthsthat persist more than 6 months

FOLLOW UPFOLLOW UP

Every 6 weeks until it resolvesEvery 6 weeks until it resolves

MRI repetititon, if resistance 3 to 6 monthsMRI repetititon, if resistance 3 to 6 months

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PARALYTIC STRABISMUS