Long-term follow up of visual pathway gliomas in neurofibromatosis type 1

Background Optic gliomas are frequently associated with neurofibromatosis t ype 1 (NF1) and belong to the diagnostic criteria of NF1. Different growth rates require differentiated strategies for screening and observation. Patients and Methods 29 patients (25 children <11 years, 4 adults >18 years ) with visual pathway tumors and NF1 were examined neurologically, ophthalm ogically, by means of MRI and VEP. Results were set into context with prece ding investigations (mean follow up time 6.5 years). Results 11 children showed a stable condition, 14 an unfavorable process wi th substantial loss of vision. Children with an unfavorable process showed a lower age at diagnosis (3.2 versus 5.8 years; p< 0.05), more frequently s trabism (11/14 versus 1/11; p < 0.05), optic atrophy (12/14 versus 1/11; p < 0.05), pathological VEP (9/9 versus 2/10; p = 0.001),visual field defects (9/9 versus 1/9) and involvement of the optic chiasm (11/14 versus 3/11; p < 0.05) than children with a stable condition. 3 of 4 adults had no visual symtoms despite involvement of the optic chiasm. Conclusions The crucial prognostic factor is the patient's age at the time of diagnosis. Optic gliomas wich become symptomatic in early childhood (< 6 years) grow rapidly and require frequent ophthalmologic investigations and MRI. Tumors diagnosed in late childhood (>6 years) do not progress, allowi ng for gradual extention of intervals between ophthalmological investigatio ns.