Selective Saccadic Palsy After Cardiac Surgery

A unique gaze palsy selectively affecting saccades while sparing smooth pursuit, vergence, and vestibular reflex eye movements has been described following uncomplicated cardiac (and especially ascending aortic) surgery . This 69 year-old man reported persistent visual complaints immediately after a type A aortic dissection repair twelve years ago. He was previously in good health with no known neurologic deficits but after developing chest pain and transient lower extremity paraparesis was found to have acute aortic dissection. He underwent ascending aorta replacement with subsequent RCA bypass graft for right ventricular failure, after which he developed difficulties with eye movement, speech, and swallowing. These deficits were initially attributed to a perioperative ischemic stroke but multiple MRIs showed no evidence of brainstem ischemia. This presentation is typical of a syndrome characterized by severe saccadic slowing and hypometria with spared smooth pursuit, vergence, and vestibulo-ocular reflex eye movements that occurs following ascending aortic and cardiac surgery . Similar to other cases, this patient also developed dysarthria, ataxia, and postural instability resembling progressive supranuclear palsy (PSP); he also developed localization-related epilepsy two years after his initial presentation. Given the sudden onset of isolated ocular motor deficits in the absence of imaging abnormalities, this selective saccadic palsy after cardiac surgery is unlikely to be due to perioperative thromboembolic events, diffuse cerebral hypoxia, or exacerbation of an unrecognized PSP-like neurodegenerative disorder. Rather, autopsy studies of similar patients suggest that selective injury to saccade-generating excitatory burst neurons and omnipause neurons (which are among the most highly metabolically active neurons in the body) or their extracellular support structures (also known as perineuronal nets) in the brainstem may be responsible for this phenomenon . In this video, we demonstrate the stable ocular motor deficits present in this patient twelve years after symptom onset. Video Description: First, the patient is asked to look left, right, up, and down but is unable to generate voluntary saccades. Next, he is asked to maintain fixation during passive head movement, demonstrating intact vestibulo-ocular reflexes. Finally, smooth pursuit is tested in all directions and is largely preserved except in upgaze.