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Valeria L N Fu, Ellen Mitchell, Anagha Medsinge, Kanwal Nischal; Electrophysiological Monitoring in Chidren with Optic Nerve Glioma. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6234.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate value of Pattern Visual Evoked Potential (VEP) as an initial tool for diagnosis and monitoring optic nerve glioma (ONG).
In a retrospective study, all children who had been diagnosed with Neurofibromatosis Type 1(NF1) were tested where possible with VEP within a mean interval of 4.4 months. Pattern VEP was performed on 23 children (age 1.1 to 13.2 years old; median age = 6.9 years old; mean age = 6.3 years old). Six children had unilateral ONG and 10 children had bilateral ONGs. Seven children had no ONG. Forty eyes were tested. Five children had multiple VEPs. All children had at least one neuroimage (MRI) taken. ONGs were confirmed with MRI scan. Visual acuity (HOTV or matching HOTV) was assessed in children older than 3 years old.
In the 16 children (age 1.6 to 13.2 years old; median age = 4.9 years old; mean age= 5.9 years old) with ONGs, seventeen of 36 eyes (47%) showed a delay in VEP latency and 18 of 36 eyes (50%) displayed a decrease in VEP amplitude. All (age 1.1 to 10.5 years old; median age=8.5 years old; mean age = 7.5 years old) but 2 children without ONG had normal VEP responses. These 2 children with abnormal VEP without ONG were found to have optic nerve pallor and anomalous optic nerves. In children with ONG (26 eyes), only 4 eyes (15%) which had abnormal visual acuity (>0.4 logMAR) showed prolongation in VEP latency and 2 eyes (17%) had abnormal visual acuity showed reduction in VEP amplitude. In a longitudinal study of 5 children with ONG who had at least 2 consecutive VEP showed that those children either displayed gradual decrease in VEP amplitude (20%) or gradual decrease in VEP amplitude and prolongation in VEP latency (80%) in a period of 2.4 to 14.4 months (average 7.2 months).
Most children with ONG displayed abnormal Pattern VEP. However, consecutive VEP revealed a gradual deterioration in VEP responses even when visual acuities remained stable. On the contrary, children with NF1 without ONG showed normal VEP responses. In summary, Pattern VEP can be considered as a helpful initial tool for assessing function of visual pathway in children with ONG.
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