Abstract
Purpose:
: Detection of progressive tumor volume in children with optic pathway gliomas (OPG) using visual acuity and visual evoked potentials (VEP).
Methods:
Patients (ranging from 0.3 to 13 years age at presentation) who were treated with chemotherapy (n = 31) or radiotherapy (n= 4) were compared to patients with stable disease and no subsequent treatment (n = 19). Patients were followed by serial magnetic resonance imaging, age-corrected visual acuity measurements in log minimum angle of resolution (logMAR), and pattern VEP. Longitudinal visual outcome data was on average 7.9 years (range 0.5 - 16 years). Sensitivity and specificity of visual acuity and VEP data were used to detect tumor volume progression as defined by 25% or greater increase in volume. We also measured longitudinal variation of acuity in patients with stable disease.
Results:
Visual acuity had poor sensitivity and specificity for detecting tumor volume progression. True positives (visual decline with tumor progression) were less frequent than false positives (visual change without tumor progression). Sensitivity/specificity improved if the analysis used a subset of patients with 0.6 logMAR acuity in the better eye, but remained poor (Sensitivity = 0.50, specificity = 0.77). VEPs were slightly better than visual acuity (sensitivity = 0.82, specificity = 0.56). In patients with stable MRI findings, longitudinal visual acuity fluctuated from -0.55 to 0.55 logMAR from the prior examination (mean = 0.0; s.d. = 0.15 log MAR).
Conclusions:
Decreased visual function does not reliably detect tumor progression. Conversely, tumor progression does not reliably indicate decreased visual function. Objective visual function and serial MRIs are complementary in management of OPG. Multiple factors can account for suboptimal sensitivity/specificity. First, visual function can decline when tumor volume is stable. Second, children with radiological stable disease show large variation in visual acuity between visits. Third, increase in tumor volume may not directly affect the visual pathway.
Keywords: 507 electrophysiology: clinical •
612 neuro-ophthalmology: diagnosis •
624 oncology