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.
North
K
K
Department of Neurology, Children's Hospital, Camperdown, Sydney, Australia.
Cochineas
C
C
Tang
E
E
Fagan
E
E
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