Neurocrit Care https://doi.org/10.1007/s12028-018-0550-8 NEUROIMAGE Insight into Ping‑Pong Gaze in the Neurosciences Intensive Care Unit Devon A. Cohen, Ali Daneshmand and Eelco F. M. Wijdicks* © 2018 Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society Keywords: Ping-pong gaze, Periodic alternating gaze, Bilateral hemispheric infarction Case Description A 76-year-old, right-handed-woman presented with leftgaze deviation, right homonymous hemianopia, global aphasia, and right-sided hemiplegia with severe sensory loss. A computed tomography (CT) head scan head showed a dense left middle cerebral artery (MCA) stroke sign. Mechanical thrombectomy achieved recanalization of the left common carotid artery and MCA. She required intubation and did not recover after recanalization, showing no eye opening to pain and a combination of flexion and extension responses without clinical improvement. Repeat CT showed a maturing MCA territory infarct. The second day, she developed smooth side-to-side horizontal movements consistent with ping-pong gaze (PPG) or short-cycle periodic alternating gaze deviation (Supplementary video), as first described by Fisher in 1967 [1]. Magnetic resonance imaging (MRI) of the brain was performed to evaluate for additional infarcts given known bilateral hemispheric localization of PPG. An MRI revealed multiple territorial infarctions with large left MCA, bilateral occipital, and smaller right basal ganglia/capsulostriatal infarcts (Fig. 1). PPG has predominantly been described in bilateral basal ganglia and hemispheric lesions, though has also occurred in midbrain and vermis lesions and toxic metabolic encephalopathies (carbon monoxide poisoning, hepatic encephalopathy, and serotonin syndrome) [2]. PPG has been attributed to cerebral disconnection from horizontal gaze centers in the relatively intact brainstem. PPG can be smooth or saccadic [3]. Smooth PPG consists of continuous conjugate eye movements between lateral *Correspondence: wijde@mayo.edu Division of Critical Care Neurology, Department of Neurology, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905, USA extremes, whereas saccadic PPG features reduced eye deviation amplitudes with a rapid lateral deviation phase and slow centripetal phase. A transition from smooth to saccadic PPG has occurred with clinical improvement [3], but there is no definitive prognostic dichotomy. A patient with smooth PPG secondary to carbon monoxide poisoning recovered [2], whereas a patient with saccadic PPG secondary to hypoxia remained in a coma [3]. Neurointensivists should recognize this eye movement abnormality as it points toward bilateral hemispheric involvement, particularly in the absence of metabolic derangements. Fig. 1 Diffusion-weighted (magnetic resonance) imaging showing large areas of restricted diffusion in middle cerebral artery stroke territory and opposite basal ganglia Electronic supplementary material The online version of this article (https​://doi.org/10.1007/s1202​8-018-0550-8) contains supplementary material, which is available to authorized users. Informed Consent Informed consent was obtained from all individual participants included in the study. Authors Contribution DAC wrote the manuscript, AD helped with the concept, EFMW is a consulting physician and the editor of the manuscript. Source of Support No funding. Compliance with Ethical Standards Conflict of Interest The authors declare that they have no conflict of interest. Human and Animal Rights All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. References 1. Fisher CM. Some neuro-ophthalmological observations. J Neurol Neurosurg Psychiatry. 1967;30(5):383–92. 2. Ishikawa H, Ishikawa S, Mukuno K. Short-cycle periodic alternating (pingpong) gaze. Neurology. 1993;43(6):1067–70. 3. Johkura K, et al. Saccadic ping-pong gaze. J Neuroophthalmol. 1998;18(1):43–6.