Central fiber contribution to W-shaped visual evoked potentials in patients with optic neuritis
✍ Scribed by Jelka Brecelj; Martin Štrucl; Marko Hawlina
- Publisher
- Springer-Verlag
- Year
- 1990
- Tongue
- English
- Weight
- 334 KB
- Volume
- 75
- Category
- Article
- ISSN
- 0012-4486
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✦ Synopsis
We studied W-shaped waveforms that occurred in full-field responses to pattern large-field stimulation in patients who had optic neuritis. Affected eyes showed no absolute scotomata; visual acuity was normal at the time of recording. To evaluate the contribution of macular-and paramacular-derived components to the development of the W-shaped waveforms in the patients, half-field and central full-field stimulation was used. The responses were compared with those obtained with the use of experimental scotomata in healthy subjects.
The W-shaped waveforrns recorded in the patients closely resembled the responses observed in healthy subjects after the introduction of experimental scotomata. In all affected eyes, half-field stimulation showed absence of the ipsilateral P100 component or its interaction with the P 135 component. Enhanced paramacular N105 and P 135 components were seen over the contralateral hemisphere. Responses to central full-field stimulation were an attenuated and prolonged P100 in the majority of affected eyes.
Results of our study showed that W-shaped waveforms in response to large full-field stimulation may reflect impaired function of macular fibers. These electrophysiologic findings, however, were not always associated with evidence of a central field defect demonstrated by Friedmann perimetry.