Mirror Image Video Artifact: An Under-Reported Digital Video-EEG Artifact

Synchronous video recording can be helpful in EEG recordings, especially in recognition of seizures and in rejection of artifacts. However, video recordings themselves are also subject to the risk of contamination by artifacts. We report a unique case in which a digital video artifact was identified, occurring during synchronous video-EEG recording, albeit independently of the EEG tracing itself. A synchronous digital video-EEG recording was performed on a 67-year-old male who presented in focal motor status epilepticus. During the initial review of the data, right-sided abnormalities on EEG apparently corresponded with (ipsilateral) right arm motor activity on video, suggesting a nonsensical anatomical localization. However, review of the patient's chart and discussion with the EEG technologist led to the recognition that the video data recorded a mirror image of the true findings of left arm motor activity. Review of the software settings led to the discovery that the video recording was inverted along the vertical axis, leading to mirror image video artifact. Recognition of this video artifact allowed for accurate interpretation of the study-that right hemispheric EEG abnormalities correlated appropriately with (contralateral) left arm twitching. Effective communication between the EEG reading physician, the treating team, and the EEG technologist is critical for recognition of such artifacts, for proper EEG interpretation, and for appropriate patient management. Mirror image video artifact affirms that bedside evaluation, astute technologists, and attentive EEG reading physicians remain important, even in the presence of video recording.