figure 1
figure 2
figure 3
figure 1 MRI T1 weighted image, mass appears isointense to brain & optic nerve tissue.
figure 2 MRI T2 weighted image, mass appears slightly hyperintense.
figure 3 MRI T1 weighted image with fat saturation after intravenous administration of gadolinium, mass presents a homogeneous intense enhancement, showing an appearance of a "tram track" around the hyperintense optic nerve.
The mass shows no intracranial or surrounding structure invasion. This tubular mass was found in the right orbit.
The patient was a 75 year old male. He was seen six years earlier with outside proptosis (forward displacement or bulging) of the right orbital bulb. Finally after six years a MRI series was done and he was diagnosed.
Primary optic nerve sheath meningioma (ONSM) account for about 1/3 of primary optic nerve tumors and 5% to 10% of orbital tumors.
The growth may be tubular, globular, fusiform or focal.
The symptoms include ipsilateral visual loss, color vision disturbance, visual field defect, proptosis, optic disc oedema and motility disturbance.
ipsilateral : same side
optic disc oedema: swelling of the optic nerve at the point where the nerve joins the eye
In 1614 Felix Plater described meningiomas during an autopsy. In 1938 Harvey Cushing described them as a separate category of extraparenchymal tumors.
These meningioma tumors are believed to arise from arachnoid cap cells. Commonly they are attached to the dura. They can form from any location where meninges exist (nasal cavity, paranasal sinuses, middle ear, mediastinum).
"In children the more common locations include the orbit, the temporal region, the foramen magnum, the tentorial region, the subfrontal base, the sellar region, and the ethmoidal air sinus." (Gossman, emedicine).
http://emedicine.medscape.com/article/1217466-overview (Gossman emedicine)
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