Although children 6 years of age and younger with NF1 are at greatest risk for the development of an OPG, new symptomatic OPGs may also arise in older children and adults. If neuroimaging is performed on all children with NF1 at the time of diagnosis, 15–20% of these children will harbor an OPG. However, only half of these tumors will ever become symptomatic, giving an overall incidence of symptomatic OPGs of 7%.
NF1-associated OPGs are usually to the anterior visual pathway, including the intraorbital optic nerve, intracranial optic nerve, and the optic chiasm (Figure 53.2). In contrast, sporadic OPGs not associated with NF1 commonly involve the optic tracts and postchiasmatic optic radiations as well. Bilateral intraorbital OPGs are virtually pathognomonic of NF1 (Figure 53.3A).Figure not available in preview mode
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Symptomatic OPGs may become apparent in one of several ways. Approximately 30% of such tumors will present with the rapid onset of unilateral proptosis and significantly decreased visual …