Fourth Nerve Palsy

Etiology and Systemic Associations Of the many causes of trochlear palsy in childhood (Table 5-5), congenital and traumatic are by far the most common.191,209 The cause of most congenital trochlear palsies remains unknown, but aplasia of the trochlear nucleus has been reported to accompany the absence of other cranial nerve nuclei.10317464 The superior oblique tendon or muscle is often the primary TABLE 5-5. Etiology of Fourth Nerve Palsy. Trauma tumor increased intracranial Cavernous sinus...

Sixth Nerve Palsies

Etiology and Systemic Associations Acquired sixth nerve palsies, whether isolated or not, are usually caused by tumors (especially glioma and medulloblastoma) and trauma (47 -62 )3,24,191,269,287,405 A significant number of cases are also due to inflammatory causes such as meningitis (including from Lyme disease), Gradenigo's syndrome,117 cerebellitis, and postviral sixth nerve palsy. The clinician is also faced with numerous other possible etiologies (Table 5-4). Clinical Features and...

Ocular Dysgenesis

Colobomatous Microphthalmia

Syndromes of ocular dysgenesis are summarized in Table 1-2. Studies of ocular malformations induced by teratogen exposure have been helpful in identifying sensitive periods during development. Microphthalmia and anophthalmia may result from insult at a number of developmental stages. Acute exposure to teratogens during early gastrulation stages results in an overall deficiency of the neural plate with subsequent reduction in size of the optic vesicle. This aberration results in microphthalmia,...

Combined Ocular Motor Nerve Palsies

As the oculomotor, trochlear, and abducens nerves are in relatively close physical proximity from brainstem to orbit, it is not surprising that many diseases occurring at numerous locations can affect these nerves simultaneously. Clinical Assessment The evaluation begins by establishing that the eye movement abnormality is due to cranial nerve disease rather than supranu-clear lesions, disorders of the neuromuscular junction, restrictive or inflammatory myopathies, or chronic progressive...

Disorders of Supranuclear Eye Movements

We focus here on a few disorders in which the normal physiology of supranuclear eye movements, such as saccade, smooth pursuit, vergence, and gaze holding, is disturbed. Saccade Initiation Failure Ocular Motor Apraxia The term saccade initiation failure or ocular motor apraxia is used to specify impaired voluntary saccades and variable deficit of fast-phase saccades during vestibular or optokinetic nystagmus.380,447 Congenital ocular motor apraxia, first described by Cogan,96 is a congenital...

Third Nerve Palsy

Scheme Iii Cranial Nerve Palsy

Etiology and Systemic Associations In childhood, a third nerve palsy typically keeps company with other neurological findings, which aid in localization and diagnosis Table 5-6 , but isolated palsies do occur and are generally congenital, traumatic, infectious, or migrainous.191,225,257,326,339,440 An acquired, isolated oculomotor nerve palsy in a child may also result from tumor, preceding viral illness, bacterial meningitis most commonly pneumococcal, Haemophilus influenzae type b, or...

Afferent Pupillary Defect Marcus Gunn Pupil

Marcus Gunn Pupil

A specific sign for optic nerve dysfunction is the presence of an afferent pupillary defect Marcus Gunn pupil . In testing for an afferent pupillary defect, room illumination should be decreased, the patient should be fixating at a distant target, and a bright light source should be used. The test compares the pupillary constriction, and hence optic nerve function, of the two eyes. The eye with the optic nerve dysfunction perceives the light source as being less bright and the pupils constrict...

Motility

The major task in evaluating a child with a motility abnormality is trying to determine whether it is caused by a common strabismus or a potentially more serious acquired disorder. The acute nature of the presentation, which is often helpful in adults, can be confusing in children as many benign entities such as accommodative esotropia can suddenly appear. In addition, many congenital motility disturbances such as Brown's syndrome and Duane's syndrome can go unnoticed for quite some time....