Dural Ectasia of the Optic Nerve: A Rare Presentation in Neurofibromatosis Type I

Neurofibromatosis Type 1 (NF-1) is a common neurocutaneous syndrome with a characteristic spectrum of pathologies affecting the optic pathway. Optic pathway glioma and optic nerve meningioma are two such common afflictions of the optic nerve in NF-1. Dural ectasia of the optic nerve also known as optic nerve meningocele is a rare manifestation of optic nerve involvement in NF-1. Magnetic resonance imaging (MRI) is an excellent modality to accurately identify, characterize, delineate, and differentiate dural ectasia of the optic nerve from the commoner lesions such as optic glioma and meningioma in NF-1. We describe a case of a young woman with NF and a large recurrent palpebral neurofibroma. MRI evaluation of the orbits revealed extensive ectasia of the dura lining the cerebrospinal fluid sheath around all the segments of the optic nerve and around the optic chiasm.