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Optic chiasm involvement on MRI with ethambutol-induced bitemporal hemianopia
Vivian B Osaguona1, James A Sharpe, Samira A Awaji
1Neuro-Ophthalmology Section, Division of Neurology, Departments of Medicine, Ophthalmology and Vision Sciences (VBO, JAS, SAA, ANES) and Medical Imaging (RIF), University Health Network, University of Toronto, Toronto, Ontario, Canada.
Summary
Ethambutol optic neuropathy can cause bitemporal visual field loss. This study details unique magnetic resonance imaging findings in the optic chiasm associated with this rare side effect of ethambutol treatment.
Area of Science:
- Ophthalmology
- Neurology
- Radiology
Background:
- Ethambutol is a first-line medication for tuberculosis.
- Optic neuropathy is a known adverse effect of ethambutol.
- Bitemporal visual field defects are an uncommon presentation of ethambutol optic neuropathy.
Observation:
- A patient with ethambutol optic neuropathy presented with bitemporal visual field loss.
- Magnetic resonance imaging (MRI) revealed abnormalities in the optic chiasm.
Findings:
- The observed MRI abnormalities in the optic chiasm are novel in the context of ethambutol-induced optic neuropathy.
- These findings suggest a potential mechanism for bitemporal hemianopia in ethambutol toxicity.
Implications:
- This case highlights the importance of neuroimaging in diagnosing atypical presentations of ethambutol optic neuropathy.
- Understanding the pathogenesis of bitemporal visual field defects may improve patient monitoring and management.
- Further research is warranted to elucidate the relationship between ethambutol, optic chiasm abnormalities, and visual field defects.
