Special Forms of Strabismus

Abbas Attarzadeh MDProfessor of ophthalmology

SUMS

Duane Syndrome

• Retraction of the globe in actual or attempted adduction.

• Horizontal eye movement is usually somewhat limited in both directions.

• Upshoot or downshoot (leash phenomenon) of the affected eye in attempted adduction

co-contraction of the medial and lateral rectus muscles and, alternatively, to slipping of the lateral rectus muscle over the outer aspect of the eye.

• Most cases of Duane syndrome are sporadic• 5%-10% show autosomal dominant

inheritance• A higher prevalence in females

In most anatomical and imaging studies, the nucleus of the sixth cranial nerve is absent, and an aberrant branch of the third cranial nerve has innervated the lateral rectus muscle

Electromyographic studies have shown: • paradoxical innervation of the lateral rectus

muscle (innervation on attempted adduction and reduced innervation on attempted abduction).

• Anomalous synergistic innervation of the medial, inferior, and superior rectus muscles and the oblique muscles

Although considered an innervational anomaly:

Tight and broadly inserted medial rectus muscles

Fibrotic lateral rectus muscles, with corresponding forced duction

abnormalities, are often encountered at surgery.

Clinical Features

1. Poor abduction, frequently with primary position esotropia

2. Poor adduction and exotropia 3. Poor abduction and adduction, with

esotropia, exotropia, or no primary position deviation

About 15% of cases are bilateral;

50%-80% in several series

DDX with sixth nerve palsy• Careful observation for globe retraction on

adduction• lack of correspondence between the absent or

typically modest primary position esotropia and the usually profound abduction deficit

• A further point of differentiation is that, even in esotropic Duane syndrome, a small-angle exotropia frequently is present in gaze to the side opposite the affected eye

ManagementIndications for surgery

1. Primary position deviations

2. Abnormal head position

3. Marked globe retraction

4. Large upshoots or downshoots

Duane syndrome with esotropia

• Recession of the medial rectus muscle on the involved side

• Bimedial rectus recession recommended for deviations over 20∆ in primary position

Resection of the lateral rectus muscle for Duane syndrome with esotropia is not favoredbecause of the likelihood that globe retraction will worsen,

although one studyreported favorable results with unilateral recession-resection procedures

Bimedial Rectus Recess

Partial or full transposition of the vertical rectus muscles has been advocated to improve abduction but may exaggerate the effects of co-contraction.

Posterior scleral fixation of the transposedportions of the vertical rectus muscles, as described by Foster, has been found helpful,

no only in Duane syndrome but in several types of paralytic strabismus as well

Surgery

The value of botulinum injection into the medial rectus muscle to improve abduction is controversial

Duane syndrome with exotropia and deficient adduction(type 2)

• Recession of the lateral rectus on the involved side for small deviations

• Both lateral recti for large deviationswith avoidance of resection of the medial rectus

The latter aspect is especiallyimportant when an up- or downshoot is present on attempted adduction, because thisfinding indicates severe co-contraction

type 3 Duane syndrome who have poor abduction and adduction

Severe globe retraction may be helped by: • Recession of both the medial and the lateral

rectus muscles• Splitting the lateral rectus muscle in a Y

configuration• A posterior fixation procedure on LR• Disinsertion of the lateral rectus muscle and

reattachment to the lateral wall of the orbit is the most recent procedure to be tried

Have straight eyes in or near the primary position and little, if any, head turn

LLR recess 13 mm + BifurcationLMR Bifurcation

BROWN SYNDROME

• Shortening of the anterior sheath of the superior oblique tendon.

• Restriction of the superior oblique tendon at the trochlear pulley

Brown syndrome was described by Harold W. Brown in 1950 as the superior oblique tendonsheath syndrome.

restriction of elevation in adduction

abandoned this theory

Brown SyndromeRestriction of the superior oblique tendon at the trochlear pulley

Brown syndrome

• Congenital

• Acquired form Trauma in the region of the trochlea Systemic inflammatory

intermittent Brown syndrome, which may resolvespontaneously.

Resolution of congenital Brown syndrome is unusual but possible

bilateral in approximately 10% of cases

Comparison of Inferior Oblique Muscle Palsy With Brown Syndrome

Inferior Oblique Muscle Palsy Brown Syndrome

Forced ductions Negative Positive

Strabismus pattern A pattern V pattern

Superior oblique muscle overaction

Usually present None or minimal

Deficient elevation in adduction that improves in abduction but often not completely

In adduction, the palpebral fissure widens and a downshoot of the involved eye is often seen; it can be distinguished from superior oblique muscle overaction because downshoot in the latter condition occurs less abruptly as adduction is increased.

Brown syndrome OSDivergence in upgaze

Down shoot in attempted elevation in adduction?

Down shoot in attempted elev. in adduct. (different than IO palsy)

Brown syndromemild moderate severe

hypotropiain primary position

no no yes

downshoot of the eye in adduction.

no yes yes

chin-up head posture and sometimes by a face turnawayfrom the affected eye insever cases

• An unequivocally positive forced duction test demonstrating restricted passive elevation

in adduction is essential for the diagnosis of Brown syndrome.

• Retropulsion of the globe during this determination stretches the

superior oblique tendon and accentuates the restriction.

When inferior rectus muscle fibrosis or inferior orbital blowout fracture(the principal entities to be differentiated) produces a restrictive elevation deficiency,the limitation to passive elevation is accentuated by forceps-induced proptosis of the eye rather than by retropulsion.

Management

• Observation alone in about two thirds of all Brown syndrome cases

• rheumatoid arthritis or other systemic inflammatory diseases

1. Systemic treatment2. Corticosteroids injected near the trochlea• Sinusitis has also led to Brown syndrome CT of the orbits and paranasal sinuses

Surgical treatment is indicated for the most severe cases

• Primary position hypotropia• Anomalous head posture

• Iatrogenic superior oblique muscle palsy may occur postoperatively. 44%-82%

sheathectomyhas been abandoned in favor of ipsilateral superior oblique tenotomy

Brown Syndrome SO tenotomy

SR

MR LR

IR

SR

LR

RMIR

IOIO

Superior oblique muscle palsy

Reduced: By careful preservation of the intermuscular

septum during tenotomy. This modification often produces an early

under correction that gradually improves with time

• Perform simultaneous ipsilateral inferior oblique muscle weakening.

• guarded tenotomy using an inert spacer sewn to the cut ends of the superior oblique tendon

• Controlling the gap between the cut ends with an adjustable sutureThese procedures eliminate the need for simultaneous inferior oblique muscle

weakening but sometimes result in a downgaze restriction due to adhesions to the nasalborder of the superior rectus muscle. Care must be taken to avoid contact of the spacer tonearby structures by preserving the intermuscular septum

For those surgeons who are a little too chicken to completely cut the SO tendon and cause a SO palsy…

Chicken suture technique

Brown Syndrome Chicken suture

For those surgeons with a sense of humor…

Try the rubber chicken trickaka silicone expander

Brown Syndrome Silicone expander

Facia Lata

THIRD CRANIAL (OCULOMOTOR) NERVE PALSY

Traumatic 3rd N palsy

The causes of third cranial nerve palsy in children

Congenital disorders (40%-50%)• Trauma • Inflammation• Viral infection• Migraine • (Infrequently) neoplastic lesions Adults• Intracranial aneurysm• Diabetes,• Neuritis• Trauma• Infection • Rarely, tumor

Diabetic third cranial nerve palsy generally resolves spontaneously within 3-4 months. The majority of adults referred for surgical treatment have palsy due to trauma

Clinical Features

Limited: • Adduction• Elevation• Depression• Exotropia and often Hypotropia• Upper lid ptosis usually is present, often with a

pseudoptosis

ABERRANT REGENERATION (MISDIRECTION)

Niknam Farshad 23 yo accident 4years ago 3rd nerve palsy aberrant regeneration

Management

Except in congenital cases of third cranial nerve palsy, it is advisable to wait 6-12 monthsfor any spontaneous recovery before surgical correction is planned.

Patients with at leastpartial recovery are much better candidates for good functional, as well as cosmetic, results,

Cured III N palsy

• Third cranial nerve palsies present difficult surgical challenges because multiple extraocular muscles as well as the levator may be involved.

• Replacing all of the lost rotational forces on the globe is impossible; therefore, the goals of surgery must be thoroughly discussed

• With patients so their expectations are realistic, Adequate alignment for binocular function in primary position and in slight downgaze for reading may be all that can be expected.

Sadravy Bahareh post surgery rt 3rd N palsy 15 years po 9.3.86

surgical procedure

• A large recession-resection procedure on the horizontal rectus muscles to correct the exodeviation, with supraplacement of both to correct the hypotropia

• Most surgeons reserve correction of ptosis for a subsequent procedure

• Some surgeons use superior oblique tenotomy instead of supraplacement of the horizontal rectus muscles for hypotropia

SIXTH CRANIAL (ABDUCENS) NERVE PALSY

Sixth nerve palsy.ppt

GRAVES EYE DISEASE

motility disturbances

• Edema, inflammation, and fibrosis are present in this disease because of lymphocytic infiltration. These conditions result in massive enlargement of affected extraocular

• muscles and may not only restrict motility but also cause compressive optic neuropathy.

Detection of this muscle enlargement by orbital ultrasound, CT, or MRI helps confirm the diagnosis of Graves eye disease.

• The myopathy is not caused by thyroid dysfunction

• Some patients with Graves disease also have myasthenia gravis

• It is mostly a disease of adults but can occur in children.

Clinical Features

• Severe restrictive, The muscles affected, in decreasing order of severity and frequency:

1. inferior rectus 2. medial rectus3. Superior rectus 4. lateral rectus

• The condition most often is bilateral and asymmetric. • Forced duction test results are almost always positive

in 1 or more directions.

• The patient presents most often with some degree of proptosis, hypotropia, or esotropia

• Upper eyelid retraction often is present.

Graves eye disease is a common cause of acquired vertical deviation in adults, especially females, but is rare in children

Management

Indications for strabismus surgery: 1. Diplopia 2. Abnormal head positionSurgery may eliminate diplopia in primary gaze but rarely restores normal motility

• It is important to establish stability of the strabismus measurements before surgery is performed

• waiting for at least 6 months is recommended.Half of the patients required repeated operation

Strengtheningprocedures are rarely performed because they usually worsen restriction

• Adjustable sutures are helpful in these difficult cases. • Slight initial undercorrection is desirable, because late

progressive overcorrection is common, especially with large inferior rectus recessions.

• Nonabsorbable sutures may decrease the likelihood of overcorrection.

• Limited depression of the eyes after inferior rectus muscle recessions can interfere with bifocal use by patients

• Proptosis can become worse after extraocular muscle recessions.

Hint

• If the need for orbital decompression is foreseeable, it is usually preferable to postpone strabismus surgery until that has been accomplishe

• Likewise, eyelid surgery usually is performed at a later time because upper eyelid retraction may be improved when the patient no longer strains to elevate the eye lid

• Large recessions of very tight inferior rectus muscles can cause lower eyelid retraction severe enough to require subsequent eyelid surgery. Severing the lower eyelid retractors

• as part of the strabismus surgery has led to some success at preventing this complication.

• If necessary, a spacer of banked sclera or synthetic material can be placed to vertically

lengthen the lower lid tarsus

Emergent basis optic nerve compression corneal exposure

Non emergent severe disfiguring proptosisdouble vision from restrictive

myopathyeyelid retraction

Which patients require surgery?

Orbital decompressionEye muscle surgeryEyelid surgeryneeds to be done in this order

Decompression affects ocular motility and may alter muscle surgery

muscle surgery should be completed before eyelid surgery

What kinds of surgery are done in patients with TRIO?

• Optic nerve compression : EOM swelling with relatively little space at the apex of

the orbit squeezing of the optic nerve at the apex of the orbit

• Severe proptosis resulting in corneal exposure or

disfigurement

Which patients require orbital decompression?

When do patients require muscle surgery?

• Double vision in functional field • Ensure that the inflammation is quiet and the

patient's motility pattern is stable• Repeated stable measurements over 6+

months help to ensure that motility is stable

What are the alternatives to muscle surgery?

• prisms in glasses works for patients with double vision and relatively small deviations

• It is better that the motility become stable before prisms are prescribed

• Temporary Fresnel prisms may be helpful during periods of instability

• Botulinum toxin A injection has a good effect in the treatment of restrictive strabismus in TAO.

• Early treatment has better results.• Dosage in TAO is higher, the mean changes of

degree of deviation is slighter, the interval between injections and the duration of effect is shorter.

• Injection dosage should increase after repeated injections.

Recession of muscles, usually on an adjustable suture basis

Muscles are tight and scarred, resection is not indicated

Inferior and medical rectus muscles are the most common targets

Forced duction test at the time of surgery is indicated

What type of muscle surgery is required?

Recession of the tight IRoften improves upper eyelid retraction: SR had to work against the tight IR, thus the

associated levator muscle was overactive, causing eyelid retraction. When the IR is recessed, the overactivity relatively ends

Large recession of IR may worsen inferior lid retraction

Does eye muscle surgery affect the eyelids?

• Eyelid retraction– Orbital decompression lowers eye, improving the

lower lid retraction– Mild lid retraction: recession of the eyelid retractors

(upper or lower) is adequate– Severe retraction: spacers are needed, such as hard

palate in the lower lids and fascia in the upper lids• Blepharoplasty and/or brow lift

– Excessive skin from chronic swelling– At the same time or later date

What kind of eyelid surgery is done?

Most do not require surgeryPatients who need surgery may

need from 1 to as many as 8-10 times over 2-3 years of reconstruction

How many surgeries do patients with TRIO require?

CHRONIC PROGRESSIVE EXTERNAL OPHTHALMOPLEGIA

Chronic Progressive External Ophthalmoplegia

Clinical Features

Chronic progressive external ophthalmoplegia (CPEO) usually begins in childhood

with:• Ptosis • Slowly progresses to total paralysis of the

eyelids and extraocular muscles

• CPEO may be sporadic or familial. • Although a true pigmentary retinal dystrophy

usually is absent, constricted fields and electro diagnostic abnormalities can occur.

• Defects in mitochondrial DNA have been found in some patients.

• The triad of :1. Retinal pigmentary changes2. CPEO3. Cardiomyopathy (especially heart block) is called Kearns-Sayre syndrome

Management

Treatment options are limited. Cautious surgical elevation (suspension) of the

upper eyelids indicated to lessen a severe chin-up head position.

MYASTHENIA GRAVIS

Myasthenia Gravis

• Onset of myasthenia gravis may occur at any age but is uncommon in children.

• A transient neonatal form, caused by the placental transfer of acetylcholine receptor antibodies of mothers with myasthenia gravis, usually subsides rapidly.

• Another variety is not immune mediated and exhibits a familial incidence.

• The disease may be purely ocular• (30%-50%) occurs as part of a major systemic

disorder• Childhood myasthenia gravis is more common

in females.

Clinical Features

• The principal ocular manifestation is extraocular muscle weakness, including weakness of the levator muscle.

• The majority of cases (90%) have both ptosis and limited ocular rotations.

• Ptosis typically increases when the patient is required to look upward for 30 seconds Sleep test, ptosis often resolves after 20-30• minutes in a dark room with the eyelids

closed. • Cogan twitch

overshootof the eyelid when the patient looks straight ahead after looking down for severalminutes

• Tensilon test• Neostigmine (Prostigmine) test• Ice test

External application of ice for 2-5 minutes improves function of the levator and otheraffected extraocular muscles, giving a rapid and reliable method of establishing this diagnosiswithout the need for drug administration.

Electromyography

• shows decreased electrical activity of involved muscles after prolonged voluntary innervation an

• increased activity (including saccadic velocity) after the administration of edrophonium or neostigmine.

• Documentation of abnormalities in single-fiber electromyography or the presence of circulating antiacetylcholine receptor antibodies is confirmatory although a negative result does not rule out

the presence ofthis disease.