Optic nerve gliomas represent approximately 4 % of all orbital tumors, 2 % of all intracranial tumors and 4 % of all gliomas.
Optic nerve gliomas outnumber Meningiomas 3 or 4 to 1.
The peak incidence is from 2 to 8 years of age with 75% manifesting in the first decade and 90% in the first two decade of life.
Spontaneous regression of an optic nerve glioma in patients with Neurofirbromatosis has been reported.
There is high association of up to 50% with Neurofibromatosis -1.
Calcifications are rare but may occur following radiation therapy, rarely tumors may extend into sphenoid sinus.
Enlargement of the optic canal is seen in more than 50% of cases.
Optic pathway gliomas are generally low-grade astrocytic tumors(pilocytic or fibrillary) that can involve the visual pathways spanning anywhere from the optic nerve to the visual cortex.
The NIH divide neurofibromatosis into :
Type 1 Von Recklinghausen syndrome, peripheral neurofibromatosis-Chromosome 17.
Autosomal dominant
Type 2- Acoustic neurofibromatosis or central neurofibromatosis. Chromosome 22
Loss of tumor suppresor function of neurofibromin leads to proliferation of neural tumors.
Neurofibromatosis 1
Diagnostic Criteria
Six or more café au lait spots
2 pigmented iris hamartomas ( Lish nodules)
Axillary, inguinal freckling
2 neurofibromas ( or 1 plexiform NF)
Optic nerve glioma 1st degree relative with NF1
Characteristic bone lesion (dysplastic greater sphenoid wing, pseudoarthrosis, cortical thinning in long bones or other distinctive osseous lesion)
Neurofibromatosis Type 2:
MISSME M-Multiple
I-Intracranial,Inherited
S-Schwannomas
M-Meningiomas
E_Ependymomas
Diagnostic Criteria for Type 2: Bilateral vestibular schwannomas
First degree relative with NF2 and 1 vestibular schwannoma
First degree relative with NF2 and 2 of the following:
Neurofibroma
Meningioma
Glioma
Schwannoma
Posterior subcapsular lenticular Opacity
Take Home Message:
Etiology for Hypertension in NF
Renal artery stenosis at its origin
Pheochromocytoma
Mid Aortic syndrome