Optic nerve glioma

Diagnosis

Optic nerve gliomas are diagnosed using magnetic resonance imaging (MRI) and CT scans. The tumor adopts a fusiform appearance, appearing wider in the middle and tapered at the ends. Enlargement of the optic nerve along with a downward kink in the mid-orbit is usually observed. While CT scans allow for optic nerve evaluation, MRI allows for intracranial evaluation to observe if the tumor has extended to other regions such as the optic chiasm and hypothalamus.

Treatment

The main goal of treating optic gliomas is to preserve vision for as long as possible. The tumor's slow and self-limiting growth indicates that it is not immediately problematic in most benign cases, with long-term studies showing that people with optic glioma may still have stable functional vision without intervention. As a result, the first and preferred course of action is usually observation of optic glioma over time.

Once the first signs of visual deterioration and/or tumor progression are observed, interventional treatments will then commence. These include radiation therapy, chemotherapy and surgical excision. While being the most effective therapy, radiation has shown damaging effects on the already compromised intellect as well as an increase in vascular issues and second tumor formation in children with neurofibromatosis 1. However, fractionated stereotactic radiation therapy (FSRT) is gaining traction as the most preferred interventional treatment for optic nerve glioma due to its combination of the therapeutic efficiency of radiation therapy without the negative side effects. Chemotherapy has also been shown to be a safer alternative to most radiation therapies and surgery for very young children (under the age of 3). However, the optimal chemotherapeutic therapy has not been defined, with risks of different toxicities still observed in older children. Surgery is considered the final choice of treatment, due to the high risk of blindness and damage to the affected eye. It is considered in only certain scenarios, such as relieving a cosmetically unappealing bulging eye (exophthalmos), removing an enlarging and/or expanding tumor or a combination of both.

Prognosis

Optic gliomas alternate between periods of inactivity and growth, making their clinical presentation variable and clinical course unpredictable. Once the optic chiasm is involved, the prognosis for life and vision worsens.

References

References

1. (1994). "The neurofibromatoses: a pathogenetic and clinical overview". Chapman & Hall.
2. Skelley, Tao Le, Vikas Bhushan, Nathan William. (2012-03-12). "First aid for the USMLE step 2 CK". McGraw-Hill Medical.
3. Goldman, Lee. "Goldman's Cecil Medicine". Elsevier Saunders.
4. (2014). "An 80-year experience with optic nerve glioma cases at the Armed Forces Institute of Pathology: evolution from museum to molecular evaluation suggests {{notatypo". Transactions of the American Ophthalmological Society.
5. (December 2011). "Diagnosis and management of optic nerve glioma". Journal of Clinical Neuroscience.
6. (16 April 2014). "Optic nerve glioma: an update". International Ophthalmology.
7. (November 2004). "Primary tumours of the optic nerve and its sheath.". Eye.