Optic Nerve Glioma

Optic Nerve Glioma
SYMPTOMS Ocular symptoms: Progressive loss of vision (about 85% of patients will have vision loss with about 60% seeing worse than 20/300), Proptosis, Diplopia, Orbital pain
Systemic symptoms: Headaches, Vomiting, Nausea
SIGNS Typically unilateral
Optic nerve edema, Optic nerve hyperemia, Loss of the cup, Blurring of the optic disc margins, Obscurations of the small vasculature at or around the optic nerve, Thickened and edematous retinal nerve fiber layer, Opacification of the retinal nerve fiber layer, Loss of sharp light reflexes around the optic disc, Splinter retinal hemorrhages, Cotton wool spots
Ultimately there will be optic nerve pallor with cupping and optocilliary shunt vessels following resolution of an optic nerve glioma or if optic nerve glioma is chronic
WORK-UP Cranial nerve testing, Pupils (decrease in direct light response and an APD in the eye with the optic nerve glioma), EOMs (may see restrictions or a nystagmus), Color vision (typically abnormal), Exophthalmometry (proptosis), Visual field (variable field loss that can be complete, centrocecal, an arcuate pattern, and an enlarged blind spot), Red cap test (reduced color brightness on side of the optic nerve glioma), Blood pressure evaluation (in order to rule out malignant hypertension), Slit lamp examination, Dilated retinal exam, Fundus photos, OCT, Fundus autofluorescence (typically normal or slight decrease in AF that extends beyond the optic disc margins), Fluorescein angiography (leakage from dilated capillaries starting in the venous stage and extending into the late stage)
OCT (Optic nerve analysis with EDI and RNFL analysis): *Elevation of the neuroretinal rim thickness *Smooth optic nerve contour *Elevation of the optic disc with involvement of the retinal nerve fiber layer with a smooth, hill-like appearance *Anterior displacement of the Bruch's/RPE complex especially near the Bruch's membrane opening *Presence of peripapillary hyper-reflective ovoid-mass like structures (PHOMS) which represent bulging optic nerve axons *Presence of subretinal fluid (presence of “lazy V sign” especially at the Bruch’s membrane opening) *Thickening of the of the RNFL with typically the nasal side being > 86 microns, temporal side being > 97 microns, superior side being > 149 microns, and inferior side being > 165 microns (Nasal RNFL thickening has the greatest specificity and sensitivity) *Subretinal hyporeflective space between the optic disc and Bruch's membrane opening (SHYPS) is >464 microns
TREATMENT Refer to a neuro-ophthalmologist/ER STAT for additional testing and treatment
Treatment includes chemotherapy and radiation
FOLLOW-UP After resolution of the optic nerve glioma, patient should be followed-up every 4-6 months
ADDITIONAL LAB | TESTS Testing will typically be ordered through the neuro-ophthalmologist/ER: MRI of the brain and orbits with and without contrast
ETIOLOGY A benign central nervous system tumor that arises from astrocytes of the optic nerve and visual pathway
DIFFERENTIAL DX Ischemic optic neuropathy, Papilledema, Optic neuritis, Diabetic papillopathy, Hypertensive optic neuropathy, Optic nerve meningioma
NOTES These type of gliomas can also involve the optic chiasm, optic tracts, optic radiations, and hypothalamus
Typically affects children (First seen between the ages of 2-6)
Accounts for about 5% of all childhood brain tumors
Commonly associated with neurofibromatosis type 1 (About 15-20% of patients with NF1 will develop an optic nerve glioma)
OCT will go from showing swelling of the RNFL to thinning of the RNFL as optic atrophy develops
Treatment typically does not result in an improvement in vision
The prognosis is typically good in children with neurofibromatosis type 1
The adult form of an optic nerve glioma has a poor prognosis as it is more likely to be malignant and metastasize
Optic Nerve Glioma: Axial MRI of a right optic nerve glioma https://www.ncbi.nlm.nih.gov/books/NBK441874/figure/article-18547.image.f1/