VEP Pattern in Brain Injured Patients According to the Involvement of Visual Pathway

J Korean Assoc EMG Electrodiagn Med 2002;4(2):67-72.
Published online May 10, 2002.

Abstract

Objectives: The purpose of this study is to investigate the VEP patterns and its clinical usefulness in assessing the involvement of visual pathway. Methods: Twenty-eight patients (17 men and 11 women) who complained of decreased visual acuity after brain injury were investigated. There were ten patients with hemorrhagic stroke, eight with cerebral infarction, and ten with traumatic brain injury. The control group were twenty-five adult without opthlamologic problem and neurologic abnormality. On the basis of the findings of brain CT and MR images, the patients were divided into two groups with the lesion on visual pathway (n=8) or without that (n=20). Full-field VEP study with the stimulation of pattern reversal and recording at Oz (center of occiput) and 5 cm lateral to Oz (O1, O2) were performed. P100 latency and N75-P100 amplitude were obtained and compared between groups. Results: There was no difference in visual acuity between the patients with visual pathway involvement and patients without involvement. The patients with visual pathway involvement showed significantly prolonged P100 latency compared with the control group (p<0.01) and the patients without visual pathway involvement (p<0.05). Conclusion: In patients who have decreased visual acuity after brain injury, VEP can be helpful to detect whether visual pathway is injured or not.

Key Words: VEP, Brain injury, Visual pathway