Optic gliomas in neurofibromatosis type 1: role of visual evoked potentials.
Optic gliomas occur in 15% of patients with neurofibromatosis type 1 (NF 1) and are a significant cause of morbidity. Of these tumors, 20-30% become symptomatic, usually before age 10 years. Previous studies have suggested that visual evoked potentials (VEPs) are a sensitive method for the detection of asymptomatic optic gliomas. Because routine neuroimaging of children with NF 1 is currently not recommended, the role of pattern-shift VEPs (PS VEPs) as a screening test for optic gliomas was evaluated. PS VEPs were performed on 10 children with NF 1 and optic gliomas and 20 children with NF 1 and normal visual pathways (as defined on MRI). PS VEPs had 90% sensitivity for detecting optic gliomas, with an increase in sensitivity to 100% when hemifield stimulation was used. The specificity of the test was 60%. Four of 20 children without optic gliomas had thickened optic nerves on computed tomography which represented dural ectasia with normal visual pathways on MRI; PS VEPs were normal in these patients. The efficacy of PS VEPs as a routine screen for optic gliomas is limited by the age at which children will cooperate with the test procedure and the high incidence of false-positive results; however, VEPs do provide a useful adjunct to routine clinical ophthalmologic assessment in the detection of optic gliomas in children with NF 1. Abnormal test results provide a stronger indication for neuroimaging. The early detection of optic gliomas allows for close monitoring of tumor progression and earlier intervention prior to significant visual loss.
Department of Neurology, Children's Hospital, Camperdown, Sydney, Australia.
K
K
North
C
C
Cochineas
E
E
Tang
E
E
Fagan
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003390:Cranial Nerve Neoplasms / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D003937:Diagnosis, Differential; D004292:Dominance, Cerebral / Q000235:genetics / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000235:genetics / Q000502:physiology*; D005260:Female; D005910:Glioma / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009456:Neurofibromatosis 1 / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D009900:Optic Nerve / Q000503:physiopathology; D009901:Optic Nerve Diseases / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D011930:Reaction Time / Q000235:genetics / Q000502:physiology; D014795:Visual Pathways / Q000503:physiopathology