Gaze-evoked and Rebound Nystagmus in a Cerebellar Syndrome

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: 30-yo-man with the subacute onset of a cerebellar syndrome. After extensive evaluation and progression, it was thought that this represented an autoimmune process and there was some improvement with immunosuppression. He had a variety of cerebellar ocular motor findings, including gaze-evoked nystagmus with rebound (e.g., left-beating nystagmus in left gaze, transitioning to right-beating when he looks back to primary), saccadic smooth pursuit and failure of VOR suppression, and saccadic dysmetria. In some cases, the distinction between physiologic end point nystagmus (EPN) and pathologic gaze-evoked nystagmus (GEN) can be difficult. Findings suggestive of EPN include relatively small amplitude, fatigues, abates in ¾ eccentric position (far enough in that both eyes can view the target), and the absence of rebound nystagmus (occasionally, normal people may have a beat or two), often with a horizontal-slight torsional (towards the ipsilateral ear) component. Findings suggestive of GEN include larger amplitude, doesn't fatigue, still present in ¾ eccentric position (far enough in that both eyes can view the target), and presence of rebound or centripetal nystagmus. Centripetal nystagmus is a nystagmus in eccentric gaze, in which the fast phase beats ""centripetally"" towards primary gaze. Video shows patient with cerebellar disease demonstrating gaze-evoked and rebound nystagmus. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This patient presented with a cerebellar degeneration of unknown etiology, and had a variety of cerebellar ocular motor findings, including gaze-evoked nystagmus with rebound (e.g., left-beating nystagmus in left gaze, transitioning to right-beating when he looks back to primary), saccadic smooth pursuit and failure of VOR suppression, and saccadic dysmetria. In some cases, the distinction between physiologic end point nystagmus (EPN) and pathologic gaze-evoked nystagmus (GEN) can be difficult. Findings suggestive of EPN include relatively small amplitude, fatigues, abates in ¾ eccentric position (far enough in that both eyes can view the target), and the absence of rebound nystagmus (occasionally, normal people may have a beat or two), often with a horizontal-slight torsional (toward the ipsilateral ear) component. Findings suggestive of GEN include larger amplitude, doesn't fatigue, still present in ¾ eccentric position (far enough in that both eyes can view the target), and presence of rebound or centripetal nystagmus. Centripetal nystagmus is a nystagmus in eccentric gaze, in which the fast phase beats "centripetally" toward primary gaze https://collections.lib.utah.edu/ark:/87278/s6089dz6