Serial pattern evoked potential recording in a case of toxic optic neuropathy due to ethambutol.
Visual evoked potentials (VEPs) were studied in a patient who developed visual impairment during ethambutol treatment. The ERG and the flash VEP were normal at the time of maximal visual loss, whereas pattern reversal VEPs 2 and 5 months after onset revealed evidence of severe bilateral optic nerve involvement, especially affecting macular fibres. Seven months after onset paramacular PNP complexes with a late positivity (scotomatous response) were recorded after pattern reversal and half-field stimulation, suggesting involvement of fibres subserving central vision. At the time when visual acuity was normal there was still electrophysiological evidence of a mild involvement of the anterior visual pathway. The papillomacular bundle seems to be especially involved in ethambutol eye toxicity.
D000368:Aged; D004977:Ethambutol / Q000009:adverse effects*; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D009901:Optic Nerve Diseases / Q000139:chemically induced* / Q000503:physiopathology; D010364:Pattern Recognition, Visual; D014795:Visual Pathways / Q000503:physiopathology
D004977:Ethambutol