Strabismus - Fundamentals of Clinical Ophthalmology.pdf

CHILDHOOD ONSET OF STRABISMUS
add weight to the theme of this book that, in
cases of strabismus, the underlying cause may
be lesions (sensory or motor) resulting in
disturbed binocular movement. The pathology
may be static but, more importantly, it may be
slowly progressive, for example gliomas of the
visual path, with no other clinical manifestations
than skin lesions that provide a clue to the
diagnosis.
In severe cases, there is bilateral complete
ptosis, divergent strabismus and no elevation or
depression of the eyes. In such cases, elevation
of the lids may aggravate exposure keratitis and
ocular muscle surgery is unrewarding. These
full-blown cases are associated with structural
change as reported by Flaherty and Gillies
(Figure 4.23).
We have also observed sporadic cases without
widespread cortical dysplasia or other clinically
significant features. The possibility that sporadic
cases represent a distinct group or form part of a
spectrum requires further study.
Opsoclonus
Opsoclonus is a rapid to and fro movement of
the eyes which has been described in children
with encephalitis and hydrocephalus. Opsoclonus
may present in infants with occult neuroblastoma
that demands neurological evaluation.
Internuclear ophthalmoplegia
Internuclear ophthalmoplegia is occasionally
seen in premature infants, possibly related to
immaturity of the medial longitudinal fasciculus.
Neonatal myasthenia gravis
Clinical manifestations of paediatric disorders
of the neuromuscular junction depend on the
mechanism and severity of the defect and age of
patient. Ptosis, strabismus, and internuclear
ophthalmoplegia have all been observed.
This disorder is seen in 10–15% of infants
born to mothers with autoimmune myasthenia
gravis. The risk is greater if there are affected
siblings. Patients with neonatal myasthenia
gravis are symptomatic at birth with facial
weakness, dysphagia, weak suck and respiratory
insufficiency.
Diagnostic tests for neonatal myasthenia
include antibodies to acetylcholine receptors and
electrodiagnostic findings similar to adults,
including descending repetitive stimulation
amplitudes with a normal compound muscle
action potential.
Congenital myasthenia occurs in infants
born to non-myasthenic mothers. This
ophthalmoplegia is not usually present in the
neonatal period. External ophthalmoplegia may
be a result of food-borne or wound botulinum.
Other eye movement
disorders – associations
with strabismus
There are a number of eye movement disorders
that present to clinicians with an interest in
strabismus. They are important because they may
be associated with strabismus but in most cases
they raise questions as to underlying aetiology and
the possibility of neurologic disease.
Congenital nystagmus
Congenital nystagmus is not usually
manifested until the early months of life.
Nystagmus has been divided according to
whether the underlying cause is thought to be
sensory or motor. However, the characteristics of
the particular movement disorder in the
nystagmus do not in themselves provide a
distinction between the two.
In some cases where the underlying basis is
sensory there may be an associated head
posture. The importance of this is that there may
be delay in diagnosis of a cerebral tumour such
as optic nerve glioma or craniopharyngioma
affecting the chiasm if the nystagmus is
misdiagnosed as motor nystagmus. 27 We found
half the infants under 5 years with optic chiasmal
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