Optic pathway glioma in children: does visual deficit correlate with radiology in focal exophytic lesions?

Purpose: Unlike pilocytic astrocytomas in other parts of the brain, optic pathway gliomas (OPG) are usually diffuse lesions involving the anterior optic pathways and hypothalamus. Their infiltrative nature often precludes complete surgical resection. We sought to determine whether careful magnetic resonance (MR) analysis, correlated with visual deficits, could be sufficient to identify those focal lesions that may be amenable to more aggressive surgical resection at presentation. Methods: We retrospectively reviewed the medical records of patients from two sites: children under 20 years of age treated for OPG between 1985 and 2009 at St Jude’s Children’s Research Hospital and children under 16 years of age treated at Great Ormond Street Hospital, London, UK, between 1984 and 2011. Patients with isolated optic nerve tumors were excluded. Visual acuity and visual field data at presentation were reviewed and correlated with MR characteristics, including extent of optic pathway involvement, symmetry, and lateral extension. Results: Two hundred and one children were treated for OPG between 1984 and 2011 in the two institutions; 74 had neurofibromatosis 1 (NF1). At presentation, visual loss was symmetrical in 132 patients and asymmetrical in 69. Potential correlation between pattern of visual loss and tumor characteristics on routine MRI was found in only 13 patients with asymmetrical vision. There was no difference between patients with and without NF1. Conclusion: The decision for aggressive surgical resection for optic pathway gliomas should be based on clinical criteria, particularly in children with good vision in one eye and poor vision in the other, as current MRI results do not reliably predict visual field deficits.