engleski

ECHOGRAPHIC PICTURE OF OPTIC NERVE GLIOMA IN NEUROFIBROMATOSIS TYPE-1

Purpose: To present echographic picture of orbital part of low-grade pilocytic astrocytoma involving optic nerve and/or chiasm and optic tract (optic pathway glioma or visual pathway glioma). Design: case series Participants: 4 children with neurofibromatosis type-1 complicated with optic pathway glioma diagnosed earlier with magnetic resonance were examined with ultrasound. Methods: Standardised A-scan technique was used for optic nerve width measurement. The 30° test and B-scan (axial, transverse and longitudinal sections) of both eyes and orbits were performed as well. Main Outcome Measures: Both eyes optic nerve width measurement, the 30° test, echographic characteristics of orbital part of the optic pathway glioma in axial, transverse and longitudinal section. Results: The optic nerve diameter in our cases ranged from 4,48 to 8,5 mm. Two children had left side optic pathway glioma, one boy had the right side optic pathway glioma and in one tumour was bilateral. Transversal section of the nerve revealed dark oval and in more perpendicular sections round void of the nerve. As the beam is swept towards the orbital apex void become more fusiform. The nerve and its sheaths are markedly widend. An abnormal increase in reflectivity and irregularity of the spike’s pattern is exibited as well. No calcification along the sheaths are noticed. Transverse section of the tumor demonstrated an “inverse doughnut” sign. The outer whiter outline of the widened sheaths surrounds an inner darker circle. This is due to characteristic tumor growth pattern. Longitudinal section revealed optic nerve head continuing into the widened optic nerve. The 30° test was negative. The differential diagnosis of meningeoma, optic neuritis and orbital cysticercosis should be considered. Conclusion: Ultrasound as cheap, safe, easily repeatable imaging method should become a method of choice for screening for optic nerve tumours in neurofibromatosis type-1, especially in children, as well as for follow-up after treatment.

echography; optic nerve glioma; neurofibromatosis type-1

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