Bilateral Radiation Optic Neuropathy Following Concurrent Chemotherapy and Radiation in Glioblastoma

Abstract

Radiation optic neuropathy (RON) is an iatrogenic complication that causes severe, irreversible vision loss within months to years following radiation to lesions close to the visual pathway. The authors describe a case of RON in glioblastoma after radio-sensitisation with temozolomide with sequential involvement of both optic nerves. This case provides a timeline for clinical and imaging findings with RON and specifically resolution of nerve enhancement. The authors also highlight the potential of an increase in incidence of RON in glioblastoma with advances in survival seen with greater use of second-line chemotherapy and even re-radiation.

Keywords: Glioblastoma; radiation optic neuropathy; temozolomide.

Figure 1.

Gadolinium-enhanced coronal (A) and axial (B) pre-surgical T1-weighted images demonstrating an irregular nodular and cystic mass in the right temporal lobe with associated shift to the left. Optic nerves (red arrowheads in A) are not displaced by the mass effect and do not enhance.

Figure 2.

Enhanced coronal post-surgical T1-weighted images showing optic nerve abnormalities following radiation and temozolomide treatment. The optic nerves are indicated by red arrows; white asterisks denote abnormal enhancement. (A) At 36 weeks after beginning of therapy, there is enhancement of the left optic nerve after exiting the optic canal. The optic tracts and intracanalicular and orbital regions of the nerve were unaffected (not shown). (B) Approximately 9 weeks after the scan shown in A, both optic nerves now enhance. Subtle enhancement of the left optic chiasm was present, but not in other regions of the nerve (not shown). (C) After a further 9 weeks, persistent but decreased enhancement is seen in the right optic nerve. (D) Isodose curves for delivered radiation to the tumour. Orange asterisks indicate optic nerve locations. Dose estimates on labeled curves: 1–30 Gy; 2–48 Gy; 3–54 Gy; 4–57 Gy.