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Radiological Interpretation in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Chirag Kamal Ahuja, Paramjeet Singh
The two major neoplasms related to the optic nerve are ONG and optic nerve sheath meningioma (ONSM). Nearly all ONGs are juvenile pilocytic astrocytomas (grade I) manifesting in childhood. The former presents as a cylindrical/fusiform thickening of the nerve with no significant enhancement (Figure 22.13). It is important to determine the extent of the lesion posteriorly along the optic nerve till the chiasma for management purpose (12). MRI is the imaging modality of choice. These lesions are isointense on T1W and iso- to hyperintense on T2W sequences with variable enhancement. Calcifications are rare. Sometimes a rim of T2 hyperintensity is seen at the tumor periphery which is leptomeningeal infiltration and not expanded CSF space, as is often thought. In NF-1, the optic nerve is tortuous, kinked, buckled and diffusely enlarged. The nerve is not separately seen from the tumor unlike meningioma. ONSM usually occurs in older adults with painless, slowly progressive loss of vision and optic nerve atrophy. It may be eccentric but is usually partially circumferential causing indentation/compression of the optic nerve, many a times leading to a “tram-track” appearance (13). The enhancement is moderate to intense (Figure 22.14). The imaging differences between the two are highlighted in Table 22.2.
Orbital malignant meningioma: a unique presentation of a rare entity
Published in Orbit, 2018
Dane H. Slentz, Sunil Bellur, M. Reza Taheri, M. Isabel Almira-Suarez, Jonathan H. Sherman, Tamer N. Mansour
Primary optic nerve sheath meningiomas originate from the meninges surrounding the optic nerve sheath. Secondary orbital meningiomas originate from the meninges of the brain parenchyma and erode through orbital bone, or infiltrate the orbit through orbital foramina. The rarest variant, orbital PEM, arises independent from the meninges of the brain and optic nerve sheath and is thought to originate from arachnoid differentiation of orbital mesenchyme, ectopic travel of arachnoid cells along orbital nerves/vessels, or entrapment of arachnoid cells in cranial sutures during childbirth or trauma.2–6,12 The tumor presented was completely separate from the optic canal and optic nerve, excluding a diagnosis of primary optic nerve sheath meningioma. Differentiating between a secondary orbital meningioma versus a PEM was more challenging.
Neuro-Ophthalmic Literature Review
Published in Neuro-Ophthalmology, 2020
David A. Bellows, Noel C.Y. Chan, John J. Chen, Hui-Chen Cheng, Peter W. MacIntosh, Jenny A. Nij Bijvank, Panitha Jindahra, Michael S. Vaphiades
Being an uncommon intraorbital tumour, optic nerve sheath meningioma (ONSM) does not only pose diagnostic but management difficulties to physicians. In the past, surgical treatment and conventional radiation usually resulted in visual loss, leaving conservative management the mainstay treatment strategy for this group of patients. However, in the recent decade, stereotatic radiotherapy (SRT) has proven its role in the management of this disorder. SRT uses fractionated irradiation to deliver a uniform dose within the radiation field. Another stereotactic irradiation technique, intensity-modulated radiation therapy (IRMT), delivers a non-uniform dose within the radiation field. Being a new technology, its role in the treatment of ONSM remains uncertain.
Optic nerve sheath meningioma
Published in Clinical and Experimental Optometry, 2019
Optic nerve sheath meningioma is a neoplasm stemming from the meningothelial cells around the optic nerve sheath. A rare condition, it accounts for two per cent of orbital tumors.2007 It is slow growing, typically monocular, and almost exclusively benign, with no deaths reported in the literature. Predilection is predominately middle‐aged women.1980 Those with neurofibromatosis type 2 have a slightly higher occurrence rate. Optic nerve sheath meningioma is rare in children, but also more aggressive.2015