Bilateral Pseudo-abducens Palsies Due to Midbrain Stroke

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a man who suffered right>left midbrain strokes due to endocarditis complaining of ptosis and inability to move his eyes as well as hallucinations (peduncular hallucinosis). There was a presumed nuclear 3rd nerve palsy on the right (i.e., responsible for his mydriatic pupil, absent supra- and infraduction, adduction, complete ptosis OD and incomplete ptosis OS, and probably responsible for at least some of his supraduction paresis OS), with partial 3rd (fascicular) nerve palsy possibly explaining infra- and supraduction paresis, unreactive pupil OS and perhaps incomplete ptosis OS. There was abducting nystagmus OS suggestive of right MLF damage or gaze-evoked nystagmus without adducting nystagmus OD due to his medial rectur palsy. In addition to adduction and vertical deficits attributable to midbrain ischemia, he also had right>left abduction pareses thought to represent pseudoabducens in the absence of pontine ischemia on several MRIs (done weeks apart), and no pontine neurologic signs on his examination. Interestingly, despite his pseudoabducens pareses being due to a presumed "supranuclear" etiology, they could not be overcome by VOR which has previously been reported. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This is a man who suffered right>left midbrain strokes due to endocarditis, who complained of the inability to move his eyes as well as dream-like hallucinations (due to peduncular hallucinosis). There was a presumed nuclear 3rd nerve palsy on the right (i.e., responsible for his mydriatic pupil, absent supra- and infraduction, adduction, complete ptosis OD and incomplete ptosis OS, and probably responsible for at least some of his supraduction paresis OS), with partial 3rd (fascicular) nerve palsy possibly explaining infra- and supraduction paresis, unreactive pupil OS and perhaps incomplete ptosis OS. In addition to adduction and vertical deficits attributable to midbrain ischemia, he also had right>left abduction pareses that were attributed to pseudo-6th or pseudoabducens palsies in the absence of pontine ischemia on several MRIs (done weeks apart), and no pontine neurologic/ ocular motor signs on his examination. Interestingly despite his pseudoabducens pareses being due to a presumed "supranuclear" etiology, they could not be overcome by VOR. This has been reported, and perhaps due to the fact that the VOR/ head impulse test is simply not a strong enough vestibular stimulus (compared to cold water calorics for instance) https://collections.lib.utah.edu/ark:/87278/s6642zc1