PARALYTIC STRABISMUS

Assist.Prof. Dr.Vildan Öztürk Ophthalmology Yeditepe University Hospital

STRABISMUS

Strabismus involves deviation of the alignment of one eye in relation to the other.

1. Non-paralytic strabismus 2. 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 eye Esotropia=Crossed eyes Exotropia=Walleye

ANATOMY

Anatomic axis Visual (optical) axis Kappa angle :

ANATOMY OF EXTRAOCULAR MUSCLES:

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

In

primary position

optical axis forms an angle of 22.5 degrees with the orbit.

the

ANATOMY OF EXTRAOCULAR MUSCLES:

Primary action of the muscle is its major effect when the eye is in primary position Subsidiary actions are the additional effects of the position of the eye Listing plane is an imaginary frontal equatorial plane passing through the center of rotation of globe. -The globe rotates left and right around the vertical Y axis -The globe moves up and down around the horizontal X axis.

-Torsional movements occur around the Z axis which traverses the globe from front to back.

Y axis Z axis X azis

EYE MOVEMENTS

Ductions

are monocular eye movements around the axis of Fick. (X, Y, Z) A

dduction

; movement of the eye nasally A

bduction;

is temporal movement

Supraduction;

elevation I

nfraduction;

depression of the eye

Incycloduction

vertical meridian (

intorsion

); nasal rotation of the

Excycloduction

(

extorsion

); temporal rotation of the vertical meridian.

SIX CARDINAL POSITIONS OF GAZE Up / right Up / left Right Left Down / right Down / left

HORIZONTAL RECTUS MUSCLES

:

-

Medial rectus

: it’s action is adduction -

Lateral rectus

: it’s sole action is abduction.

VERTICAL RECTUS MUSCLES

Superior rectus:

 primary action is elevation  secondary actions are adduction and intorsion

Inferior rectus

:   primary action is depression secondary actions are adduction and extorsion

OBLIQUE MUSCLES

Superior oblique muscle

– incyclotorsion. – depression – abduction

Inferior oblique muscle

– excyclotorsion – elevation – abduction

Muscle Innervation Primary action

Medial rectus CN III Superior rectus CN III Inferior rectus CN III Inferior oblique CN III Superior oblique CN IV Lateral rectus CN VI Adduction Abduction

Secondary action

- --

Tertiary action

- Elevation Depression Extorsion Intortion Extortion Elevation Intorsion Depression Adduction Adduction Abduction Abduction --

Tillaux’nun Spirali

LAWS OF OCULAR MOTILITY

Agonist

: the primary muscle that moves an eye in a given direction

Synergist

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

Antagonist

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

Sherrington Law

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

LAWS OF OCULAR MOTILITY

Yoke muscles

– Primary muscles in each eye that accomplish a given version.

– Each extra ocular muscle has a yoke muscle in the opposite eye to accomplish versions into each gaze position.

Herring Law

; – Yoke muscles receive equal and simultaneous innervation; – Magnitude is determined by the fixating eye.

BINOCULAR EYE MOVEMENTS Conjugate (versions)

are movements of both eyes in the same direction

-Dextroversion

is movement of both eyes to the right,

-Levoversion

is movement of both eyes to the left.

-Supraversion;

elevation of both eyes,

-Infraversion;

depression of both eyes,

BİNOCULAR EYE MOVEMENTS Disconjugate (vergences

)

are movements of the eyes in opposite directions. -

Convergence

nasally is movement of both eyes -

Divergence

temporally. is movement of both eyes -

Vertical vergence

occur.

movements also may

TYPES OF STRABISMUS Esotropia

is inward turning

Exotropia is

outward turning

Hypertropia

is upward turning

Hypotropia

is downward turning of the eye.

ESOTROPIA

EXOTROPIA

HYPERTROPIA

HYPOTROPIA

HIRSCHBERG TEST

DIPLOPIA

Simultaneous appreciation of two images of one object. It results from a failure to maintain binocular vision.

Binocular, monocular, physiological

MUSCLE INNERVATIONS

medial rectus (MR) —cranial nerve III lateral rectus (LR) —cranial nerve VI superior rectus (SR) —cranial nerve III inferior rectus (IR) —cranial nerve III superior oblique (SO) —cranial nerve IV inferior oblique (IO) —cranial nerve III

Extra ocular muscle paralysis

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

(LR 6 SO 4 ) 3

OCULAR MOTOR NERVE PALSIES 1. Third nerve 2. Fourth nerve 3. Sixth nerve

OCULOMOTOR (III.) NERVE PALSY

•

The oculomotor nerve innervates

• superior rectus, inferior rectus, medial rectus, • inferior oblique, • levator palpebrae, • ciliary muscle • iris sphincter.

OCULOMOTOR (III.) NERVE PALSY

Red nucleus Anatomy of third nerve Oculomotor nucleus Pituitary gland Carotid artery Cavernous sinus Pons Post cerebral artery Clivus Basilar artery III nerve

Nuclear portion Fascicular portion – intraparenchymal midbrain portion – – – subarachnoid portion cavernous sinus portion orbital portion

OCULOMOTOR (III.) NERVE PALSY

ANATOMY

The pupillomotor and ciliary muscle neurons derive from the Edinger-Westphal subnucleus, which is in the midline in the most rostral and anterior part of the oculomotor nerve nucleus. These autonomic pathways are all ipsilateral or uncrossed

Applied anatomy of pupillomotor nerve fibres Blood vessels on pia mater supply surface of the nerve including pupillary fibres ( damaged by compressive lesions ) Vasa nervorum supply part of nerve but not pupillary fibres ( damaged by medical lesions ) Pupillary fibres lie dorsal and peripheral

OCULOMOTOR (III.) NERVE PALSY

ETIOLOGY

A-

Pupil involving

More common: Aneurysm ( particularly a post. communicating artery aneurysm) Less common: Ischemic microvascular disease ( DM or HT), tumour, trauma, congenital Rare: Uncal herniation, cavernous sinus mass lesion, pituatery apoplexy, orbital disease, herpes zoster, leukemia, in children ophthalmoplegic migraine

OCULOMOTOR (III.) NERVE PALSY

ETIOLOGY

B-

Pupil –sparing

: Ischemic microvascular disease; rarely cavernous sinus syndrome, giant cell arteritis (GCA) C-

Relative pupil-sparing

: Ischemic microvascular disease; less likely aneurysm

Etiology

Important causes of isolated third nerve palsy Idiopathic - about 25% Vascular disease - hypertension, diabetes Trauma Posterior communicating aneurysm Midbrain pushed across Extradural haematoma Chiasm Aneurysm Edge of tentorium Prolapsing temporal lobe Third nerve Posterior cerebral artery

OCULOMOTOR (III.) NERVE PALSY

ETİOLOGY

Nuclear and fascicular midbrain portion – Infarction – Hemorrhage – Neoplasm – Abscess

OCULOMOTOR (III.) NERVE PALSY

ETIOLOGY

–

Fascicular midbrain portion infarcts Benedikt syndrome

– upper mid brain includes – ipsilateral third cranial nerve palsy – contralateral flapping hand tremor – ataxia

Weber syndrome

– slightly more ventral lesion at the level of the third cranial nerve fascicles in the mid brain – ipsilateral third cranial nerve palsy – contralateral hemiplegia or hemiparesis

OCULOMOTOR (III.) NERVE PALSY

ETIOLOGY

Fascicular subarachnoid portion – Aneurysm – Infectious meningitis - Bacterial, fungal/parasitic, viral – Meningeal infiltrative – Carcinomatous / lymphomatous / leukemic infiltration, granulomatous inflammation (sarcoidosis, lymphomatoid granulomatosis, Wegener granulomatosis)

OCULOMOTOR (III.) NERVE PALSY

ETIOLOGY

Fascicular cavernous sinus portion – Tumor - Pituitary adenoma, meningioma, craniopharyngioma, metastatic carcinoma – Vascular – Giant intracavernous aneurysm – Carotid artery-cavernous sinus fistula – Carotid dural branch-cavernous sinus fistula – Cavernous sinus thrombosis – Ischemia from microvascular disease in vasa nervosa – Inflammatory - Tolosa-Hunt syndrome (idiopathic or granulomatous inflammation)

OCULOMOTOR (III.) NERVE PALSY

ETIOLOGY

Fascicular orbital portion – Inflammatory, orbital inflammatory pseudotumor, orbital myositis – Endocrine (thyroid orbitopathy) – Tumor (hemangioma, lymphangioma, meningioma)

OCULOMOTOR (III.) NERVE PALSY

FREQUENCY

%30 of paralytic strabismus

MORTALİTY / MORBİDİTY

subarachnoid hemorrhage from berry aneurysm of the posterior communicating artery meningitis or meningeal infiltrative disorders, both infectious and neoplastic

OCULOMOTOR (III.) NERVE PALSY

SYMPTOMS

Binocular diplopia Ptosis Mydriasis With or without pain

Signs of right third nerve palsy

•

Ptosis, mydriasis and cycloplegia

•

Abduction in primary position

•

Normal abduction

•

Intorsion on attempted downgaze

•

Limited adduction

•

Limited elevation

•

Limited depression

OCULOMOTOR (III.) NERVE PALSY

CRITICAL SIGNS

External ophthalmoplegia ( motility impaired) 1-Complete palsy: Limitation of ocular movement in all fields of gaze except temporally 2-Incomplete palsy:partial limitation of ocular movement 3-Superior division palsy: Ptosis and inability to look up 4-Inferior division palsy: Inability to look nasally or inferiorly: pupil is involved

OCULOMOTOR (III.) NERVE PALSY

CRITICAL SIGNS

Internal ophthalmoplegia ( Pupil reaction impaired) 1-Pupil involving: A fixed, dilated minimally reactive pupil.

2-Relative pupil sparing: Pupil partially dilated 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

OCULOMOTOR (III.) NERVE PALSY

WORKUP

History Complete ocular examination, Hess chart Full neurologic examination Internal medicine examination Imaging study MRI CT Cerebral angiography

OCULOMOTOR (III.) NERVE PALSY

WORKUP

Lumbar puncture

Histological findings

CBC ESR

OCULOMOTOR (III.) NERVE PALSY

TREATMENT

Treat the underlying abnormality If diplopia, an occlusion patch ( not for children) or prisms NSAIDs commonly are used to treat the pain in ischemic third cranial nerve palsy.

Surgery may be performed after 6 months Botulinum toxin injections

OCULOMOTOR (III.) NERVE PALSY

FOLLOW UP

Pupil sparing: Observe daily for 5 to 7 days Recheck every 4 to 6 weeks If the function is not regained in 3 months, refer to the internist+MRI Pupil involving If imaging and angiography are negative, follow as pupil sparing case

OCULOMOTOR (III.) NERVE PALSY

Medical / Legal Pitfalls:

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

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

Trochlear (IV.) nerve palsy

In 1935, Bielschowsky correctly noted that trochlear nerve palsy was the most common cause of vertical diplopia and introduced his classic head-tilt test. With greater clinical interest, the number of identified fourth nerve palsies has increased.

Trochlear (IV.) nerve palsy

The fourth cranial nerve innervates superior oblique muscle – intorts – depresses – abducts the globe. Can be congenital or acquired, unilateral or bilateral.

SO-LID

Anatomy of fourth nerve Internal carotid artery Postr. communicating artery III VI Postr.cerebral artery Supr.cerebellar artery Basilar artery IV

• •

Only cranial nerve to emerge dorsally Crossed cranial nerve

•

Very long and slender

Trochlear (IV.) nerve palsy

Frequency

% 11 of all paralytic strabismus

Trochlear (IV.) nerve palsy

Pathophysiology

Congenital

lesions are frequent. Head posture is gained.

– secondary to dysgenesis of fourth nerve nucleus – abnormalities of peripheral nerve – abnormal superior oblique muscle or tendon

Trochlear (IV.) nerve palsy

Pathophysiology

Acquired

– The long course of the trochlear nerve makes it especially susceptible to injury in association with severe head trauma . Contrecoup forces can compress the nerve against the rigid tentorium – Vascular lesions are common.

Trochlear (IV.) nerve palsy

Etiology:

Idiopathic, Severe head trauma, Microvasculopathy secondary to diabetes, atherosclerosis, or hypertension There are rare reports of thyroid ophthalmopathy and myasthenia gravis presenting as isolated fourth nerve palsy.

Trochlear (IV.) nerve palsy

Etiology

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

Trochlear (IV.) nerve palsy

SYMPTOMS

Binocular vertical diplopia Reading diffuculty Sensation that objects appear tilted May be asymptomatic

Signs of right fourth nerve palsy

• •

Right hyperdeviation in primary position when left eye fixating Excyclotorsion

• •

Right underaction on depression in adduction Vertical diplopia

•

Right overaction on left gaze

Trochlear (IV.) nerve palsy

SIGNS

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

Positive Bielschowsky test in right fourth nerve palsy Increase in right hyperdeviation on ipsilateral head tilt Absence of right hyperdeviation on contralateral head tilt

Trochlear (IV.) nerve palsy

THREE-STEP TEST

Each step reduces by half the number of possible affected muscles until only 1 remains. First step is to identify the hypertropic eye in primary gaze. – This implicates depressors of hypertropic eye or elevators of hypotropic eye. Second step is to ascertain if hypertropia is worse on left gaze or right gaze. – This will identify 4 muscles that act in that direction of gaze. Third step is to determine if hypertropia is worse on right head tilt or left head tilt.

Trochlear (IV.) nerve palsy

WORKUP

History Old photographs ESR, fasting blood sugar, blood pressure MRI, CT Three step test Hess 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

Trochlear (IV.) nerve palsy

TREATMENT

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

FOLLOW UP

Congenital IV. Nerve palsy; routine Acquired IV. Nerve palsy; Follow of the underlying cause If work up negative, follow monthly up to 6 month, then surgery may be needed

ABDUCENS (VI.) NERVE PALSY

Innervates the ipsilateral lateral rectus which functions to abduct the ipsilateral eye. It has the longest subarachnoid course of all the cranial nerves; therefore, its syndromes are similar to those of the fourth nerve because of their long intracranial courses.

Anatomy of sixth nerve Basilar artery Medial lemniscus Pituitary gland Carotid artery 4th ventricle Cavernous sinus Vestibular nucleus Clivus Pyramidal tract Petroclinoid ligament VI nerve

ABDUCENS (VI.) NERVE PALSY ETIOLOGY

Younger patients; postviral syndrome, trauma, increased intracranial pressure, pontine glioma, Gradenigo ’s syndrome Adult population; vasculopathic, increased intracranial pressure, GCA, cavernous sinus mass

FREQUENCY

The most commonly affected of the ocular motor nerves; % 45 of paralytic strabismus

Important causes of isolated sixth nerve palsy Vascular - hypertension, diabetes Raised intracranial pressure Acoustic neuroma Dilated ventricles Petrous tip Brainstem pushed downwards

ABDUCENS (VI.) NERVE PALSY

Mortality/Morbidity:

A young patient should have aggressive workup because of the greater likelihood of a neoplasm causing the palsy. Patients older than 40 years require a less aggressive workup because of the greater likelihood of the etiology being more benign in nature mononeuropathy eg ischemic

SYMPTOMS

Patients usually present with horizontal diplopia( side by side image) and an esotropia in primary gaze. Esotropia Head-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 t o 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

WORKUP

Adults History Neurologic and ophthalmologic examination Blood pressure , fasting blood sugar, ESR MRI of the brain Children History Neurologic and ophthalmologic examination Otoscopic examination MRI

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

TREATMENT

Underlying cause treated Occlusion patch or prism in spectacles for adults Strabismus surgery for stable deviations that persist more than 6 months

FOLLOW UP

Every 6 weeks until it resolves MRI repetititon, if resistance 3 to 6 months