of compressive optic neuropathy, such as intentional globe subluxation, should be also considered, even in nonpsychotic children.86

Noncompressive Causes of Optic Atrophy in Children with Brain Tumors

In addition to the direct effect of the tumor itself, optic neuropathies may be seen in children with brain tumors due to several other potential etiologies (1) Toxic effect of chemotherapy (e.g., vincristine).799 Vincristine has been implicated in various ophthalmological disturbances including optic atrophy,799 transient cortical visual impairment, ptosis, and ophthalmoplegia. Disruption of the blood–brain barrier by both radiation and surgical manipulation may increase its toxic potential.799 (2) Paraneoplastic optic neuropathy. (3) Radiation optic neuropathy. Toxic optic neuropathy will be discussed later in this chapter.

Postpapilledema Optic Atrophy

Postpapilledema optic atrophy is often associated with specific ophthalmoscopic findings that suggest the underlying mechanism of injury (Fig. 4.9). Any of the following findings in association with optic atrophy suggest previous optic disc swelling (1) a fine fibrous sheathing of the retinal vessels as they emanate from the disc, (2) opaque fibrous tissue overlying the disc and obscuring the peripapillary retina, (3)

circumpapillary pigment changes (“high water marks”), and

(4) optociliary shunt vessels.

In addition to brain tumors (especially posterior fossa tumors, but also craniopharyngioma), major causes of postpapilledema optic atrophy in children include shunt failure, pseudotumor cerebri, and craniosynostosis, among others. These entities are detailed in Chap. 3. The efficacy of optic nerve sheath fenestration in preventing visual loss in patients with severe or intractable papilledema is now well established. The benefits of optic nerve sheath fenestration in children are now well established,858 and many cases of postpapilledema optic atrophy in children are now preventable with early intervention.

Paraneoplastic Syndromes

Optic atrophy may rarely result from paraneoplastic axonal degeneration. Paraneoplastic retinal degeneration is much more common in adults than in children. In contrast, paraneoplastic ocular motility disorders (e.g., opsoclonus-myo- clonus in neuroblastoma) are more common in children.40,773 Presumed paraneoplastic retinal degeneration and optic atrophy was recently described in a 6-year-old boy who had an embryonal rhabdomyosarcoma of the thorax.344 A few cases of presumed paraneoplastic optic neuropathy have been described in adult patients. In some such cases, retinal pigmentary abnormalities are absent, and marked arteriolar narrowing may be the only sign of underlying retinal dysfunction. The diagnosis is established by finding an attenuated or extinguished ERG signal.

Fig. 4.9  Postpapilledema optic atrophy in a patient with chronic pseudotumor cerebri. Note bilateral disc pallor with indistinct margins and circumpapillary “high-water” marks. There is prepapillary and

peripapillary glial proliferation which produces a wispy vascular sheathing and radial peripapillary striae