Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

Ptosis in children is mostly congenital in origin and less commonly acquired. In adults the incidence of congenital to acquired ptosis is reversed.

Ptosis in children have two pressing factors for management i.e. cosmetic blemish and possibility of developments of amblyopia. However acquired ptosis in children have an added factor of systemic neurological involvement that may be crippling, blinding even life threatening.

It is of utmost importance that all drooping upper lids do not constitute true ptosis. There are many condition of the lid, globe or orbit that may mimic ptosis and are grouped as pseudo ptosis. Pseudo ptosis can be mechanical when a growth or edema of the upper lid causes narrowing of the interpalpebral fissure. Otherwise the lid may be normal in the function and appearance but it seems to droop due to change in shape, size and position of the eyeball in relation to orbit. Occasionally the lid may be normal with normal inter palpebral aperture but seems to be drooping because the contra lateral eye has a wider inter palpebral fissure which is considered to be normal.

Causes of pseudo ptosis can be—

4.Miscellaneous — Duane’s retraction syndrome

—Hypotropia of contra lateral side

—Hypertropia of ipsilateral side

Classification of ptosis1,2,4

Traditionally ptosis has been divided into two groups:

1.Congenital ptosis

2.Acquired ptosis

Other widely used classification is based on anatomical structures involved— 1. Congenital (i) Simple congenital - only levator muscle is involved.

(ii) Complicated congenital ptosis

(a) Other muscles along with LPS are involved. (b) Third nerve or sympathetic nerve involved. (c) Along with other congenital anomalies of lids. (d) Ptosis with synkinetic movements.

2. Acquired ptosis —(i)Mechanical (a) Edema lids

(b) Tumours of lid (ii) Neurogenic

(a) Third nerve palsy (i) Upper division (ii) Both divisions (iii) Trunk

(iv) Nucleus

(b) Along with other cranial nerves.

(c) Cervial sympathetic involvement— Horner’s syndrome

(iii) Myogenic—

(a) Myasthenia

(b) Muscular dystrophies

(c) Chronic progressive ophthalmoplegia and it’s variations (iv) Aponeurotic — Traumato levator aponeurosis

Congenital ptosis

This is the commonest form of ptosis seen in children and lingers on to adult life if not corrected. It accounts for about sixty percent of all ptosis in childhood. There are various modes of presentation1

1.Due to congenital fault in (i) Levator alone

(ii) Levator Superior rectus complex (iii) Third nerve

2. Birth trauma (i) To LPS

(ii) Third nerve

(iii) Cervical sympathetic

Ptosis due to congenital fault in levator palpebral superior only (simple ptosis)

This type comprises of 75%-80% of all congenital ptosis. This is also known as simple ptosis. It is inherited as autosomal dominant trait.1 It is unilateral in seventy five percent of cases. The bilateral cases are generally symmetrical. The ptosis is said to be complete when there is no action of the levator. In congenital ptosis some action of levator is always present hence most of them are called incomplete. Boys and girls are involved equally. There may be many members of the family to have congenital ptosis including the siblings. Congenital simple ptosis is non progressive and stationary unless corrected surgically. It is generally present at birth but most often missed because a newborn keeps his eyes closed for eighteen to twenty hours. Of course in cases of rare instances of severe ptosis, the parents may notice its presence at birth. Unilateral ptosis draws attention early than bilateral. The condition may be so small that it goes unnoticed unless the child looks up or develops abnormal head posture.

The appearance of bilateral ptosis is characteristic. The forehead skin is thrown in horizontal furrows, the eyebrows are arched up. The head is tilted back. Head tilt and arching of the eyebrows are acquired late when the child realises that by doing so he has better vision.

The inter palpebral fissure is narrow with some action of levator.

The skin of the lid is smooth, unwrinkled. The tarsal fold is generally absent. The other extra ocular muscles including orbicularis are normal. Pupillary reaction and accommodation are normal. Child with unilateral ptosis may raise the eyebrow on the same side only. The forehead furrow and the head tilt are less marked in unilateral ptosis.

The lid droops down over the cornea, the drooping varies in different cases, it may be mild, moderate or severe, depending upon available levator function. In a normal child if the upper lid is everted and child looks up, the lid is automatically corrected but not in congenital ptosis where most of the action of levator is absent.

The vision is normal. However associated error of refraction, which is mostly astigmatism and causes subnormal vision. In severe cases the pupil may be obscured with severe loss of vision, unless the lids are lifted. The other cause of diminished vision isamblyopia, which is more often anisometropic than deprivation. Prolonged amblyopia may result in strabismus.

The cause of maldevelopment of levator is not well understood. Various suggestions given are:

1.It is due to lack of peripheral differentiation or aplasia of muscle.

2.Dystrophy or degeneration of levator.

3.Unknown trauma to the levator.

4.Abnormal development of levator.

5.The striated muscle fibres are replaced by fibro fatty tissue.5

Congenital ptosis associated with defects in other extraocular muscles

These are generally put under heading of complicated congenital ptosis.

1. The commonest association is involvement of superior rectus on the same side.

During developement of the led a superior rectus and levator develop from a common mesodermal mass and are closely associated with each other until late in development. The nerve supply to the levator i.e. upper division of third nerve also supplies the superior rectus and is also likely to share common dystrophic changes. Hence involvement of both the muscles is a common feature.

Involvement of superior rectus does not produce expected diplopia. It may be associated with under action of inferior oblique. There may occasionally be an elevator palsy. Bell’s phenomenon may be minimally affected or absent. It is also not associated with changes in pupillary reaction or accommodation. Other extraocular muscles have normal movement. There are no synkinetic movements. Presence of diplopia on lifting, the lid denotes involvement of extraocular muscles other than superior rectus alone.

2.Congenital ptosis may be associated with under action of other extra ocular muscles supplied by third nerve due to developmental anomaly like hypoplasia of the third nerve nuclei or its trunk.

3.Rarely there may be congenital anomaly of other cranial nerves supplying the extra ocular muscles.

4.Congenital ptosis associated with under action of cervical sympathetic. This is rare and mostly due to traction trauma to the brachial plexes during delivery.1

5.Rarely neonatal myasthenia may present as congenital ptosis.9

Congenital ptosis associated with other congenital anomalies of lid These consist of—

—Ptosis

—Inverse epicanthic fold

—Blepharophimosis

—Telecanthus

The tetrad is called blepharophimosis syndrome.6

Blepharophimosis syndrome

The tetrad is an inherited disorder. All the features may not be present in all the cases all the time. 3% to 6% of children with congenital ptosis have blepharophimosis. Some may have just epicanthus inversus and ptosis.

In blepharophimosis the inter palpebral fissure is shortened in length as well as width. The epicanthus inversus is a fold of skin on the medial side of the medial canthus extending from lower lid upward. In telecanthus the inter canthal distance is increased. The child keeps the head tilted back. Other anomalies found are squint, punctal displacement, coloboma of optic nerve head6. The condition is bilateral, equally seen in boys and girls.

Treatment—

The definitive treatment is surgical correction of each deformity in various sittings. The surgical treatment can be deferred up to age of five years in absence of amblyopia. The medial canthal deformity is corrected six to twelve months before the ptosis surgery.

Congenital ptosis associated with synkinetic movements of the lids

The synkinetic movements can be—

1.Jaw movement

2.Ocular movements

1.Ptosis with jaw movements is also known as Marcus Gunn jaw winking and inverse Marcus Gunn jaw winking. Jaw winking is present in four to six percent of all congenital ptosis.6 Jaw winking is more common than inverse jaw winking. The former is caused due to contraction of external pterygoid muscle and latter is due to contraction of internal pterygoid muscle. The syndrome of jaw winking is due to congenital misdirection of fifth nerve to the levator.

Jaw winking is present at birth and first noticed by the mother who observes that the position of the upper lid changes when the child suckles. Later the parents notice that there is involuntary spasmodic jerky retraction of upper lid with certain movements of the lower jaw i.e. moving the jaw to contra lateral side, projecting the jaw forwards or opening the mouth.

In inverse jaw winking, the lid may elevate on closing the mouth or clinching the mouth, the lid may be ptotic or may be normal.

The jaw winking is generally unilateral, present at birth and remains for rest of the life. The child may learn to suppress it later to overcome embarrassment. It is also known to become less severe as the child grows. It is mostly sporadic, may be seen in several members of the family.

Treatment consists of surgical correction, before that any amblyopia or anisometropia present may be corrected.

Surgical treatment is definitive treatment that requires correction of two separate features - ptosis and jaw winking present simultaneously. Jaw winking when severe may be worsened by levator resection so one of the modes of surgery is to release the levator aponeurosis that worsen the ptosis which is later corrected by frontalis suspension.7

Congenital ptosis associated with abnormal ocular movements1,3,8,9

Fibres destined for medial rectus are directed to superior rectus or inferior oblique. Fibres of inferior rectus may be directed to the pupil. Hence many combination are possible. Some of the common combinations are -

1.Lifting of upper lid in attempted adduction.

2.Paradoxical retraction of upper lid on the affected side in congenital paralysis of sixth nerve.

3.Raising of lid in downward gaze (Pseudo Graefe sign).

4.Lid retraction on occlusion of contra lateral eye.10 The ipsilateral eye is generally ptotic with jaw winking.

Paralytic ptosis

Paralytic ptosis can be due to

1.Involvement of third nerve.

2.Involvement of cervical sympathetic.

1. Ptosis in third nerve involvement. It can either be congenital or acquired. Congenital ptosis due to third nerve palsy is less common than congenital ptosis due to levator dysplasia. Ptosis due to oculomotor palsy is far more common in adults than in children. In adults, diabetes, vascular lesions and neoplasm are more common than infection. In children infection is more frequent cause of paralytic ptosis than others. However third nerve involvement in which ptosis is an outstanding feature may be the only sign to begin with, this may be followed by serious central nervous involvement that may not only be vision threatening but crippling or life threatening.

Oculomotor ptosis can be due to—

Nuclear, facicular, basilar and peripheral involvement.

The nuclear lesions are rare. It consists of bilateral, symmetric ptosis with superior rectus under-action. May be isolated, may precede palsies of other muscles supplied by third nerve. Due to its proximity to fourth nerve nucleus, fourth nerve involvement is also common.

Supra nuclear lesions cause mild ptosis with subnormal gaze palsy and miosis.

Mid brain lesions are associated with signs of dorsal or ventral fascicular lesion i.e. Benedicts syndrome, and Webers syndrome. Trunk may be involved either in cavernous sinus or orbit.

Treatment should be—

1.Directed towards the cause.

2.Surgical intervention is deferred for about six months after ptosis has been stabilised.

3.Amblyopia is treated by standard method.

Sympathetic ptosis (Horner’s syndrome)11,12

Sympathetic ptosis occurs due to involvement of oculosympathetic chain anywhere from hypothalmus to eye causing in a number of signs that constitute Horner’s syndrome. For diagnostic purposes the oculo sympathetic is divided into three anatomic part consisting of three neuron.13

1.The first neuron extends from posterior hypothalmus to cilio spinal centre of Budge between C8 and T2.

2.The second neuron extends from centre of Budge to superior cervical ganglion in the neck.

3.The third neuron spreads from superior cervical ganglion to the eye via nasociliary and long ciliary nerves.

Incidence of Horner’s syndrome is less common in children than in adults. It can be congenital or acquired. The acquired causes in children are birth trauma mostly to the brachial plexus associated with Klumke’s paralysis. Some authors believe that congenital Horner’s syndrome is nothing but a result of birth trauma. Besides birth trauma accidental injury to neck, enlarged lymph nodes in neck, cavernous sinus disease, inflammation in orbit can cause Horner’s syndrome.

The features of Horner’s syndrome consists of—

1.Permanent signs and

2.Transient features

The permanent features are: 1. Ptosis

(i) Ptosis is mild, not more than 2 mm to 3 mm due to paralysis of Muller’s muscle. (ii) The lid folds are retained.

(iii) There is no lid lag on upward gaze.

(iv) The action of LPS and superior rectus are normal.

2.Upside down ptosis of the lower lid: The retractor muscle of lower lid is also supplied by oculo sympathetic hence its paralysis results in upward shift of the lower lid. The normal lower lid that just touches the lower limbus covers the lower 1 mm of the cornea.

3.Narrowing of inter palpebral aperture: This is due to combined effect of ptosis and upside ptosis.

4.Enophthalmos: This is more of a pseudo enophthalmos than true. The eye looks small due to ptosis and upside ptosis.

5.Miosis: The pupil on the affected side is smaller by 0.5 mm to 1.00 mm and not pin point. It is best observed in dim light. The pupil does not dilate with 4% cocaine. The pupil will dilate with hydroxyamphetamine 1% (Paredrine) in pre ganglionic lesion but not in post ganglionic lesion.

6.Anhydrosis of the affected side of the face.

7.Heterochromia of the iris on the affected side. The iris on affected side is lighter. This is characteristic of congenital Horner’s syndrome in children.13

The transient signs

1.Dilatation of conjunctival vessels.

2.Dilated facial vessels.

3.Reduced intraocular pressure.

4.Increased accommodation.

There is no change in convergence and light pupillary reaction.

Differential diagnosis consists of all causes of unilateral small pupil - Congenital miosis, traumatic miosis, healed iridocyclitis.

Treatment

There is no known treatment for Horner’s syndrome. Attention should be directed to the cause of Horner’s syndrome, which are confirmed by -

1. Pharmacological test (i) Cocaine test (ii) Paredrin test

2.x-ray chest

3.CT and MRI

4.Neurological evaluation

Neuro muscular (Myogenic) ptosis

There are two types of myogenic ptosis:

1.Fault at myoneural junction.

2.Myopathies and muscle dystrophies.

Both are more common in adult but can be seen in children and may be congenital or neonatal.

1. Fault in myoneural junction

Myasthenia gravis15,16,17: Myasthenia gravis is an auto immune disorder that produces extra ocular muscle hypofunction without involving intrinsic muscle. It is of two types:

1. Ocular and 2. Systemic

About 90% of patients with myasthenia have predominantly ocular involvement that may precede systemic involvement in 75% of cases, 80% of cases with ocular involvement will be gradually converted into systemic involvement in two years14,15 Chances of conversion to systemic myasthenia after two years is less common. It is not a hereditary disease but may be seen in members of the same family.3 Infants born to myasthenic mothers are prone to develop neonatal myasthenia, which may be present at birth. Myasthenia is more common in women than in men in a ratio of 2:1. However childhood myasthenia is more common in girls i.e. girls to boys ratio is 6:1.17

Myasthenia can be progressive or remittent.

Myasthenia is a common cause of acquired ptosis and diplopia in all ages without other neurological involvement. It can affect any age from birth to late seventh decade but common age group is between 20-40 years. About six percent of cases may develop dysthroid oculopathy later.

Exact etiology of myasthenia is not known. It is presumed to be an autoimmune disorder. Acetyl choline, which is a pharmacological transmitter at neuro muscular junction is destroyed fast by an unknown substance present at the neuro muscular junction. This unknown substance19 has curare like action that renders the muscle hypoactive and fatigued. There is reduction of acetylcholine receptors at motor end plate20,21 Use of anticholine estrase drugs rectify this process, this forms the basis of medial treatment of myasthenia.

Ocular symptoms of myasthenia gravis

Two main symptoms are 1. Ptosis and 2. Diplopia. There may be concurrent or one may follow one another.

Ptosis: Drooping of upper lid in myasthenia is variable though it is bilateral, may begin in one eye. The other eye follows soon. In bilateral ptosis drooping is systemic. It may shift from one eye to the other eye. Drooping changes not only in days but may be in hours. It is generally minimal or absent on waking up and gradually increases during active hours becoming maximum in the evening.

Variability is demonstrated by following tests:

1.Cogan lid twitch: The patient is asked to look down for 10-15 seconds and then asked to fix the eye in primary position quickly. This sends the upper lid higher than normal, only to fall to ptotic position.

2.Lid fatigue: With sustained upward gaze, the ptosis becomes more.

3.Cold test: An ice cube is applied to the ptotic eye for about two minutes. On removal of the ice, the lid is markedly elevated which falls to ptotic level in 15 seconds.

4.If the contra lateral lid is lifted mechanically there is enhanced ptosis in ipsilateral side.

5.Under action of orbicularis is almost constant feature in myasthenic ptosis.

6.Improvement of ptosis following Tensilon test.

7.Therapeutic trial by oral prostigmine and pyridostigmine shows improvement in ptosis and reduction of diplopia.

Diplopia

Diplopia is one of the most common and sometimes first symptom experienced by the patient. It varies in type and extent. It is more often vertical than horizontal. It becomes worse in the evening.

Squint

Some patient may notice squint. Extraocular muscle involvement does not follow any fixed pattern. Muscle imbalance may simulate inter nuclear ophthalmoplegia or central gaze palsy.16 There may be nystagmoid movements. Extra ocular muscles to be involved other than levator is orbicularis, Muller’s muscle is never affected. Patient may present with heterophoria. Commonest being exophoria. Any of the skeletal muscles can be affected. Common are the small muscles of face, laryngeal muscle, muscles of mastification, most probably due to involvement of bulbar muscles.17

Involvement of thymus is common.

Myasthenia of childhood differs from adult myasthenia. There are three types of myasthenia in children -

1.Transient neonatal myasthenia seen in children born to mothers who have the disease.

2.Persistent neonatal myasthenia: This is similar to transient myasthenia but mothers do not have the disease.

3.Juvenile myasthenia sets in after ten years of age. The presentation is similar to adult myasthenia.

Differential diagnosis

All cases of variable ptosis, diplopia with orbicularis weakness and normal pupil should be suspected to have myasthenia unless proved otherwise. The conditions that constitute differential diagnosis are:

— Chronic progressive external ophthalmoplegia and its variations.

—Myotonic dystrophy

—Inter nuclear ophthalmoplegia

—Dysthyroid myopathy.

Diagnosis of myasthenia

Diagnosis of established myasthenia is not difficult however may have to be confirmed

by

I. Pharmacological test—Tensilon test.22

1.To do this test first precaution is to have a resuscitation trolley ready and handy.

2.Inject 0.3 mg atropine I.V. (adjust dose in children).

3.Fill a syringe with 10 mg Tensilon.

4.Inject 2 mg I.V. and observe for any adverse reaction or improvement.

In adverse reaction, abandon the test and consider therapeutic trial with oral prostigmine. In case of improvement in ptosis, facial expression and diplopia, the test is conclusive that may be further confirmed by injecting remaining 8 mg.23

Three types of responses are possible:

1.An improvement.

2.Worsening: Small tropia becomes large tropia.

3.Reversal: Squint shifts to the other eye.

The response in 2 and 3 are not seen in true myasthenia. II. Antibody to anti actycholine is present in 90% cases.

III. x-ray chest, CT and MRI of mediastinum may show thymoma.

Management

Myasthenia is a self limiting disease. In many children it will pass off after one or two episodes without recurrence. Others will require medical treatment and complete amelioration may be achieved and child maintained on a maintenance dose for long time. Most of children in this group will have some residual ptosis and or manifest muscle imbalance that requires surgical correction later. Surgical correction should not be done unless there is no recurrence for one year, ptosis and squint are stable for at least one year.

Medical treatment

Medical treatment consists of oral a anticholineesterase drugs given in divided doses. Most commonly used drug is pyridostigmine. Its effect starts with in 10-30 minutes following oral administration and lasts for three to four hours with peak in between. Hence the drug has to be repeated every four to six hours. Correct dose is adjusted empirically in consultation with pediatrician.

Other drug used is prostigmine which is less effective than pyridostigmine.

It takes two to three days for prostigmine to be effective. The side effects of the drug are colic, diarrhoea, nausea due to prasympathomimetic action of the drug. These are reduced if the drug is taken with food or some spasmolytic drugs are taken few minutes after the drug.