Neurogenic Conditions

Neurogenic Conditions

Fourth Nerve (or Superior Oblique) Palsy

Common as both congenital and acquired Can be bilateral or unilateral

Aetiology

Familial defect of nerve or its nucleus, or major brain abnormality

Many unknown Head injury, eg damage to trochlea in upper cut

blow in boxing Diabetes Intracranial tumour

Characteristics

Bielschowsky Head Tilt Test : this differentiates SO palsy from the contralateral SR Palsy

Ocular Posture

Unilateral palsies: affected eye hypertropic and slightly esotropic Excyclotropia likely

» Hypertropia increases on near fixation» Slight V pattern

Bilateral palsies:» Constant V pattern esotropia with hypertropia of the non-fixing

eye

» Extorsion of non-fixing eye in acquired only

AHP

Unilateral: (I) Head tilt to sound side (ii) Face turn to sound side (iii) Chin Depression All are to overcome the vertical diplopia Bilateral: Chin depression

Hess Chart

Field of BSV is displaced upwards (and to affected side in unilateral)

Management

Acquired unilateral palsy = vertical prism Others = surgery 90% of isolated unilateral palsies (except

some traumatic ones) recover spontaneously within 6 months.

Sixth Nerve (Lateral Rectus) Palsy

Common Aetiology

» Birth trauma: instrumentation, increases intracranial pressure presses nerve against the petrous temporal bone

» Childhood: meningitis, otitis media, pneumonia etc» Adult:trauma, demyelinating disease, intracranial space

occupying lesions

» Old Age: CVA

Characteristics

Ocular Posture esotropia on distance fixation with less for near (or only phoria at near)

Crossed fixation and equal VA in congenital bilateral type

AHP

Unilateral = face turn to affected side (esp in distance fixation)

Hess Chart

Field of BSV displaced to unaffected side in unilateral

Management

Prism base out to distance portion of bifocals Botulinium toxin A injection into MR reduces

esotropia to alleviate diplopia and prevents contracture of ipsilateral MR

Occlusion to prevent amblyopia in children Surgery

Related Syndromes to 6th Nerve Palsy

Mobius’ syndrome Congenital. Due to close association of 6th and 7th cranial nerves in the mid-

brain This syndrome is bilateral 6th and 7th nerve palsies, causing loss

of abduction and facial weakness (not necessarily symmetrical) Expressionless face, incomplete lid closure, bilateral loss of

abduction etc

Graderigos Syndrome

LR palsy caused by a middle ear infection which spreads to the petrous bone causing swelling and affecting the 5th (Trigeminal) and 6th nerves

Results in 6th nerve palsy, ipsilateral trigeminal pain of the face, deafness and facial turn to the affected side

This condition is rare since the advent of antibiotics

3rd Nerve Palsy (Ophthalmoplegia)

Mostly unilateral Possible causes: Birth injury, head injury,

diabetes, hypertension, compression by posterior communicating artery aneurysm

Classification

Complete Oculomotor Palsy affects all extra- and intra- ocular muscles.

Divergent strabismus with slight depression, ptosis, mydriasis, loss of pupil action accommodation

Partial Paresis

External ophthalmoplegia (all external ocular muscles only)

Internal ophthalmoplegia (paresis of ciliary muscle and iris sphincter)

Superior division of 3rd Nerve (SR and levator) Inferior division (IR, MR, IO, ciliary muscle and

sphincter Double elevator palsy (SR and IO). Congenital

Single Muscle Paresis (usually congenital)

SR with V pattern exotropia (usually accompanied by ptosis)

MR (very rare) IR (least common)

Cyclic Oculomotor Palsy

intermittant 3rd Nerve Palsy. Rare, ? Cause An acquired SR palsy is generally accompanied by ptosis

since the SR and levator share the superior division of the 3rd nerve and are anatomically in close proximity

Often get accompanying symptoms eg HIA, a tremor of the contalateral limbs (due to involvement of the Red Nucleus = Benedikts’ syndrome, and other diabetic symptoms).

Management

Prisms – limited use (diplopia only present if incomplete ptosis)

Botulinum toxin A – injection into LR can be helpful

Pilocarpine 0.1% to reduce photophobia Surgery

Mechanical Restriction of Ocular Movement

Duane’s Retraction Syndrome

Congenital Bilateral or unilateral – more often affecting

LE Incidence higher in females

Characteristics

One or all of: Limitation of abduction with widening of palpebral aperture Less marked limitation of adduction in the same eye Retraction of globe on adduction with narrowing of

palpebral apertures Poor convergence Face turn to affected side

Classification

TYPE A:Limited abduction, less marked limitation of adduction

TYPE B:Limited abduction but normal adduction TYPE C:Limitation of adduction exceeds

limitation of abduction.Exotropia and face turn

Aetiology

Innervation of the LR by extra branches of the 3rd nerve in place of an absent or atrophic 6th nerve

Simultaneous contraction of MR and LR resulting in retraction

Lack of abduction because lack of 6th nerve innervation Fibrosis of LR results, and hence mechanical

restriction

Management

Treatment of amblyopia and correction of refractive error

Surgery for cosmetic correction of AHP, if necessary.

Starbismus Fixus

Characteristics Very marked Esotropia Fibrosis and contracture of both MR – hence adduction of both eyes Absence of active and passive horizontal eye movement Face turn to side of fixing eye Rare Presents in infancy Uncertain if fibrosis of MR is a primary condition or secondary to LR

paralysis

Adherence Syndromes

Either: congenital adherence of extra-ocular muscles to each other or to facial tissue or levator

Familial Or: acquired due to infection, trauma or more

surgery (especially strabismus or retinal detachment surgery)

Management; Surgery

Brown’s Syndrome (or Superior Oblique Tendon

Sheath Syndrome)

Develops in infancy, or acquired later through inflammation (eg rheumatoid arthritis) or trauma in the trochlear region.

Mainly unilateral, can be bilateral

Characteristics

Limitation of elevation in adduction Overaction of the contralateral SR but other muscle sequelae do not

develop (therefore no defect in lower field) A or V pattern Typical Hess chart In some acquired cases with repeated attempts to look up and in an

audible ‘click’ is heard and eye suddenly shoots up with overacting IO AHP: tilt to affected side (Not always present) Positive forced duction test (Negative in IO palsy)

Aetiology

Uncertain and variable. Main causes: Short tendon sheath Presence of swelling on SO Tendon

preventing free passage through trochlea

Management

Most spontaneously recover Some surgery for cosmetic correction of

AHP

Blow-Out Fracture

Caused by direct blow to eye through closed lids Wave of pressure causes orbital floor to fracture,

and a portion of orbital tissue may become trapped

This restricts rotation of the globe, particularly up and down

Management

May recover spontaneously within 2 weeks Others require surgery to free trapped tissue

Myogenic Palsies

One in which the weakness of ocular movement is due to a primary problem affecting the muscle itself rather one disrupting the nerve supply or causing mechanical restriction.

Myasthenia Gravis

Comparatively rare disorder of neuromuscular transmission Onset 20-40 years. Characterised by excessive fatiguability of striated muscle, most commonly the

EOMs but may be more generalised. Diplopia and Ptosis are often presenting symptoms, which worsen during the

day. May later progress to a more generalised muscle involvement. The condition generally stabilises and then help may be gained with prisms,

ptosis props or surgery. Can get ptosis and can be confused with 3rd nerve palsy

Orbital Myositis

Inflammatory swelling of one or more of the EOMs.

Self limiting and resolves in about 8 weeks

Rhabdomyosarcoma

Highly malignant tumour of the striated muscle

May produce a strabismus and restriction of ocular movement or acute proptosis

Usually in childhood

Dysthyroid Eye Disease (Ophthalmic Grave’s Disease)

Can occur in hyperthyroidism (thyrotoxicosis) Or hypothyroidism (myxoedema) But is most common in the former Can present as a muscle palsy without exophthalmus Limitation of elevation, but more than one muscle is

affected, in the following sequence swelling of EOM (wet phase) = MYOGENIC fibrosis and secondary muscle contracture, especially of the

IR (dry phase) = RESTRICTIVE

Dysthyroid Eye Disease (Ophthalmic Grave’s Disease)

Other eye signs: proptosis, von Graefe’s sign, lid retraction, decreased blinking chemosis and vertical diplopia

Other symptoms may be:» increased/decreased appetite (depends on whether hyper/hypo)» decrease/increase weight» clammy hands» increased/decreased heart rate» anxiety/lethargy

» Tremor in hyper

Other systemic conditions causing ocular palsies

Diabetes Disease of the small blood vessel network (vaso nervorum) May cause acquired 3rd, 4th or 6th Nerve palsy (Third most

common) Usually spares the pupil (these fibres lie superficially in

Third Nerve and are not supplied by small vessel network as much)

Diplopia

Other symptoms:severe headache, increased thirst,

increased urination, increased appetite,decreased weight,

constipation, boils and skin conditions.

More common in older overweight females.

Diabetes

Other symptoms:» severe headache, » increased thirst, » increased urination, » increased appetite,» decreased weight, » constipation, » boils and skin conditions.

» More common in older overweight females.

Hypertension

Most commonly affects the 6th nerve, mostly in old age

Symptoms: » Headache, » dizziness, » breathlessness, » tinitis

Temporal arteritis (Giant Cell Arteritis)

Inflammatory disease of temporal artery occurring in over 60s Rarely presents as isolated oculomotor nerve palsy Symptoms:

» scalp tenderness,» headache, » prominent temporal arteries, » general malaise

» weight loss

Multiple Sclerosis

Ocular palsy is an early symptom in many patients

Other symptoms: loss of muscle coordination, limb weakness, slurring of speech

THERE ARE MANY CONDITIONS WITH OCULAR PALSY AS ONE OF THE FEATURES. THESE ARE THE MOST COMMON.