reduced.

Table 26-2

Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH), or pseudotumor cerebri, is characterized by increased ICP with normal-sized or small ventricles on neuroimaging, and normal cerebrospinal fluid. IIH is uncommon in childhood but can occur at any age. It may be associated with viral infections, drug use (tetracycline, corticosteroids, vitamin A, nalidixic acid, thyroid medications, and growth hormone), and cerebral venous sinus thrombosis. Prepubescent children with IIH have a lower incidence of obesity compared with adult IIH patients, and the male to female ratio is approximately equal. Postpubescent children with IIH have a clinical profile similar to that of adults, with a higher incidence of obesity and female sex preponderance. Down syndrome is also associated with IIH.

Common presenting symptoms are headache, vision loss, transient visual obscurations, and diplopia. Papilledema may be noted on routine examination of an asymptomatic child. Ocular examination frequently reveals excellent visual acuity with bilateral papilledema. Unilateral or bilateral sixth nerve palsy may be present. The patient should be monitored closely for decreased visual acuity, visual field loss, and worsening headaches. Visual field tests can be difficult to interpret in children but should be obtained if possible.

Treatment of IIH begins with discontinuation of any causative medications. Medical treatment includes acetazolamide and topiramate. Surgical treatment options include optic nerve sheath fenestration or shunting procedures (lumbar or ventriculoperitoneal), both of which can reduce the incidence of vision loss. Shunting procedures are preferred for patients with good visual function and severe headaches unresponsive to medical management. With treatment the visual prognosis is excellent for most patients, although vision loss can occur secondary to chronic papilledema. In most cases, spontaneous resolution occurs within 12–18 months after initial treatment.

Pseudopapilledema

Pseudopapilledema refers to any elevated anomaly of the optic disc that resembles papilledema (see Table 26-2). Disc anomalies that are frequently confused with papilledema in children include drusen, hyperopia, and prominent glial tissue. Pseudopapilledema can be differentiated from true papilledema by the absence of disc hyperemia and retinal hemorrhages and exudates and by the lack of systemic

findings associated with increased ICP (Fig 26-12A). Pseudopapilledema is associated with anomalous branching of the large retinal vessels.

Figure 26-12 A, Pseudopapilledema. There is anomalous branching (arrows) of the large retinal vessels without disc hyperemia, retinal hemorrhages, or exudates. B, Optic nerve head drusen seen as refractile opacities on disc surface (arrows). C, Ultrasonographic image of bright spot in nerve (arrows) consistent with drusen. (Parts A and B courtesy of Paul Phillips,

MD; part C courtesy of Edward G. Buckley, MD.)

Most children with pseudopapilledema do not have other related ophthalmic or systemic abnormalities. However, pseudopapilledema is associated with Down syndrome, Alagille syndrome, and retinitis pigmentosa. Down syndrome is associated with IIH as well; thus, an elevated optic disc in a child with Down syndrome should not be assumed to be benign. If there are clinical symptoms and signs of elevated ICP (headaches, sixth nerve palsy, true papilledema), neuroimaging followed by lumbar puncture should be obtained.

Drusen

Intrapapillary drusen, the most common cause of pseudopapilledema in children, can appear within

the first or second decade of life (Fig 26-12B). Drusen are frequently inherited (autosomal dominant); thus, examination of the parents is helpful when drusen are suspected in children.

Clinically, the elevated disc does not obscure the retinal arterioles lying anteriorly and often has an irregular border suggesting the presence of drusen beneath the surface. There is no dilation of the papillary network, and superficial retinal hemorrhages and exudates are absent. Peripapillary subretinal hemorrhages and subretinal neovascular membranes rarely occur. When drusen are not buried, they appear as shiny refractile bodies visible on the disc surface, with a gray-yellow translucent appearance. Visual field defects are frequently associated; inferior nasal field defects are common. Concentric narrowing, an arcuate scotoma, and central defects can also occur. These defects can be slowly progressive. Central visual acuity is rarely affected.

In some patients, fundus evaluation can identify drusen as the cause of the swollen disc appearance. Occasionally, however, such identification cannot be made with certainty, and B-scan ultrasonography can be helpful in detecting bright calcific reflections at the optic nerve head (Fig 26-12C). Computed tomography can also detect these drusen.

Most children with optic disc drusen do not have other related ophthalmic or systemic abnormalities. However, children with pseudoxanthoma elasticum or retinitis pigmentosa have a higher incidence of optic disc drusen compared with the general population.