Fig. 19.10. a Aicardi syndrome. Circumpapillary chorioretinal lacunae in a young girl. The disease is lethal in males. b Aicardi syndrome. Hypoplasia of the corpus callosum (arrow) and cortical heterotopia
Nystagmus in Childhood
Proper diagnostic classification of congenital or neonatal nystagmus is challenging. A practical schema is illustrated in the flow diagram of ■ Fig. 19.11 (see also Chap. 11).
Sensory defect nystagmus (SDN), or ocular nystagmus that arises from a congenital defect in retinal and/or optic nerve development, is in 80% of all cases considerably more common than congenital idiopathic nystagmus, which is a diagnosis of exclusion. A precise diagnostic classification allows for an accurate prognosis and assessment of the risk of recurrence in subsequent children by the same parents. Both forms can have characteristics that allow exclusion of more widespread neurological disease. Only if these characteristics are identifiable can either of the two be correctly diagnosed. When findings are uncharacteristic, complete neuropediatric and neuroradiologic examinations are required. This also holds true when complex combinations of nystagmus and other neurological disorders are mixed.
■ Table 19.9 summarizes the most frequently found disorders in children with SDN (ocular nystagmus). A form of albinism is found in more than one third of cases.
Table 19.9. The most common causes of SDN or ocular nystagmus, based on heredofamilial diseases of the retina or optic nerve
Disorders with macular hypoplasia
• Aniridia (also minimal variants with limited iris changes)
• Isolated macular hypoplasia
• Progressive cone (cone/rod) dystrophies
- Leber's congenital amaurosis (LCA) (various forms)
- Early onset retinitis pigmentosa
• Stationary cone disease
- Achromatopsia (autosomal recessive, various forms)
- Blue-cone monochromacy (X-linked)
X-linked congenital stationary night blindness (CSNB)
• Incomplete form (CSNB2)
Optic disc hypoplasia
Familial isolated nystagmus (autosomal-dominant and X-linked forms)
See Chap. 11. 256
Pathological nystagmus in children
Sensory deficit Idiopathic Neurological
Sensory deficit Idiopathic Neurological
Cerebral Disorders of Vision in Children Definition
Cerebral disturbances of vision are impairments of vision caused by intracranial damage to the afferent visual pathways up to the level of the primary visual cortex. They can be found only by use of neuroradio-logical examination.
A cerebral disturbance of vision with an unremarkable fundus appearance is a certifying sign of intracranial disease affecting the afferent visual pathways up to the level of the visual cortex. This definition is important in some countries, since any specific claim for compensation based on visual loss requires confirmation of this sort of intracranial disease. ■ Table 19.10 provides a summary view of the etiologies of cerebral disorders of vision in children.
tent LN), NN neurological nystagmus, RN rebound nystagmus, SDN sensory deficit nystagmus. Published in D. Taylor's textbook Paedi-atric Ophthalmology (see "Further Reading")
Table 19.10. Cerebral causes of visual damage in childhood (excluding tumors)
• Infections of the central nervous system
• Intentional cranial trauma in child abuse, marked by fundus hemorrhages
• Hypoxic/ischemic encephalopathy
• Following brain hemorrhages (e.g., in prematurity)
• Secondary to a status epilepticus
• Subacute, sclerosing leukoencephalopathy
• Carbon monoxide poisoning
Table 19.11. Neuroradiologic signs associated with cerebral causes of visual damage (excluding tumors)
■ Table 19.11 lists the typical neuroradiologic findings in such cases. If the damage is present at birth, or appears in the first 3 to 6 months of life, fundus changes such as optic disc atrophy or pathological cupping will often be present, caused by descending transsynaptic degeneration.
Periventricular Leukomalacia Definition
Periventricular leukomalacia is a softening of the white matter in the regions surrounding the ventricles of the brain.
Radiologically demonstrable periventricular leukomalacia is an important sign of cerebral damage in premature infants and those suffering from perinatal cerebral asphyxia. It can present with optic disc cupping that should be distinguished from the sort caused by congenital glaucoma. Associated disturbances of vision can escape detection when only spatial acuity is tested, since acuities can be largely normal in the face of significant visual loss. Other problems associated with damage to visually associated regions of cerebral cortex become apparent only later, when learning disabilities are exposed in primary school-aged children.
Ocular manifestations of congenital CNS diseases can also be found, attributable to disturbances of cellular induction, migration, and proliferation. Other congenital anomalies of the brainstem and cerebellum often accompany these disorders, as summarized in ■ Table 19.12. In addition, a variety of brain tumors lead to ocular symptoms. A detailed discussion of congenital intracranial tumors is beyond the scope of this chapter, but it is dealt with more completely in Chap. 12. In all such cases the neuroradiologic findings are conclusive.
Table 19.12. Congenital brain lesions with ocular manifestations (excluding tumors)
Disorders of induction
• Arnold-Chiari malformation
• Septooptic dysplasia
Disorders of cell migration and proliferation
• Fetal alcohol syndrome
• Fetal hydantoin syndrome
• Lissencephaly (agenesis of cerebral gyri)
Other congenital anomalies of the brainstem and cerebellum
• Moebius' syndrome
• Joubert's syndrome
• Dandy-Walker cysts
Delayed visual maturation can occur as an isolated entity. Typically such children are noted at an age of 2 to 3 months to behave as blind, and yet seem to have normal pupillary light responses. (A differential diagnosis should include Leber's congenital amaurosis [LCA], which can be confirmed by absent or severely impaired pupillary light reactions and an undetectable or severely reduced electroret-inogram [ERG].) Often, a response of the child to facial appearances may be present when light responses seem to be absent. By the age of 6 months this feature will typically become inapparent. Neither morphological nor electro-physiologic studies will show any detectable disease. Delayed visual maturation can also occur in company with retinal or intracranial diseases.
Differential Diagnosis of Unexplained Visual Loss - Psychogenic Disturbances of Vision (Functional Visual Loss)
Unexplained acquired visual loss in children can result from macular diseases that at first escape detection. This is particularly true in the early stages of Stargardt's disease. Typically, a psychogenic cause is suspected during the early stages of discovery. The diagnosis is often made by multifocal ERG (or by pattern ERG), and more recently by the detection of increased fundus autofluorescence at a wavelength of488 nm. Correct diagnosis of an X-linked retinoschisis can be particularly difficult when only macular
Periventricular leukomalacia Infarcts in the parieto-occipital region Infarcts in the occipital lobes changes are present. Only with precise optical examinations can schisis be found. This ordinarily requires the use of optical coherence tomography (OCT). Electrophysiolo-gy (see Chap. 7) can confirm the diagnosis.
Migraine equivalents produce the most highly varied forms of visual hallucinations, and can often be early signs of cerebral diseases that can be found only by appropriate neuroradiologic study. Psychogenic (functional) disorders of vision often pose serious problems with differential diagnosis (see Chap. 15). They constitute a diagnosis by exclusion. A high level of suspicion of a psychogenic disturbance should accompany findings, such as highly variable visual responses - as reflected, for instance, in the spiraling of isopters plotted during kinetic perimetry. If a profound unilateral loss of vision is claimed, conflicting data such as normal stereoacuity, absence of a relative afferent pupillary defect, or intact acuity demonstrated with polarizing filter isolation of test characters to one eye or the other during binocular reading usually permits a decisive determination of the psychogenic character of the visual loss.
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