Abstracts

Rationale: The use of synchronous video and EEG recording is beneficial for recognition of seizures and artifacts. Characteristic findings on video review may even help confirm a diagnosis when scalp EEG findings are inconclusive. Simultaneous video-EEG recording has become standard in many settings; however, video recordings themselves are subject to risk of contamination by artifacts, albeit in a different manner than digital and analog EEG recordings. We present a case of an under-reported artifact (mirror image video artifact) that could have led to video-EEG misinterpretation. Methods: A 67-year-old male with renal cell carcinoma and right fronto-parietal brain metastasis (status post resection) initially presented in focal motor status epilepticus, with reported left arm twitching. The seizures temporarily resolved with intravenous lorazepam but subsequently recurred, and the patient had persistent left arm weakness. Continuous video-EEG was initiated; this EEG and clinical patient data were reviewed. Results: Initial EEG review showed right hemispheric sharp waves occasionally occurring in periodic trains, in the setting of generalized delta activity (at times, sharp waves had a bilateral posterior predominance, right > left). On video review, the patient appeared to have twitches and decreased movement of the right arm, though the technologist's annotations noted left arm twitching. However, multiple documented neurological examinations reported twitching and weakness in the left arm only; moreover, MRI confirmed the presence of right fronto-parietal post-operative changes. However, this could not explain the apparent new finding of right arm twitching on video. Discussion with the EEG technologist who performed the study confirmed that the clinical findings were truly left sided. We subsequently recognized other inconsistencies on video (wedding ring on "right" hand, inverted/mirrored hospital logo, and phone cord attached to the incorrect side of the base). Review of recording software settings led to the discovery that the video recording was inverted along the y-axis; the "horizontal flipping" setting was inadvertently toggled on, leading to the mirror image video artifact (see Figure). Conclusions: To our knowledge, this is the first report of mirror image video artifact. In this case, the artifact occurred due to inadvertent toggling of the y-axis inversion function of the recording software. It is possible that such toggling is included to allow correction for certain rotated camera positions. For example, a camera mounted upside down (180 degree rotation) would need inversion along both x- and y-axes to have accurate, upright images on video review. Each laboratory should be aware of such features in their equipment, as this artifact may have alternate causes and solutions depending on the specific hardware and software being used. In summary, video artifacts, such as mirror image, are important to recognize. Effective communication between reading neurologists, primary teams, and EEG technologists is critical to ensure such artifacts do not lead to video-EEG misinterpretation and improper patient management. Funding: n/a