Abnormalities of the pattern evoked potential in compression of the anterior visual pathways

Abstract

The great majority of patients with compression of the anterior visual pathways of sufficient severity to give rise to visual symptoms have abnormal pattern evoked potentials, even in the absence of the usual objective signs of optic nerve damage. The technique promises to be of particular value in the early detection of involvement of the second eye. While asymmetry of the P.E.P. suggests compression rather than primary demyelinating disease, there are no specific features which allow one to distinguish with certainty between optic neuritis and tumor. The observation of abnormal responses with normal acuity, discs and fields is in accord with the findings in multiple sclerosis, and together the results indicate that the evoked potential technique provides a uniquely sensitive means of detecting optic nerve damage. The cause of the damage cannot be decided electrically and can only be established by the clinical context.