Periodic Alternating Nystagmus and Perverted Head-shaking Nystagmus in Cerebellar Degeneration

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a 60-yo-woman with several years of worsening imbalance, diplopia (hers was actually unrelated to cerebellar pathology [although she did have an esotropia greater at distance that was cerebellar in origin] and due to thyroid eye disease) and blurry vision (due to her spontaneous nystagmus). There was also corectopia OD and she was status post cataract surgery in this eye. Examination demonstrated alternating right-beating and left-beating nystagmus every 90 or so seconds (with a null period in between) consistent with periodic alternating nystagmus (PAN). PAN localizes to the nodulus and uvula, and is occasionally seen with cerebellar degenerations (SCA 6 among others). Baclofen can be helpful for PAN, and therapy was initiated in this particular patient. She also had hypermetric saccades, choppy smooth pursuit and VOR suppression, gaze-evoked nystagmus, as well as perverted nystagmus with head-shaking - i.e., with horizontal head-shaking, vertical nystagmus (downbeating) was apparent). This is another central vestibular/ocular motor sign, and can also be seen with nodulus/uvula pathology - this finding can be seen at the end of the video. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This patient presented with progressive imbalance and oscillopsia over years, and examination demonstrated alternating right-beating and left-beating nystagmus every 90-120 seconds (with a null period in between) consistent with PAN. PAN localizes to the nodulus/ ventral uvula, and is occasionally seen with cerebellar degenerations (SCA 6 among others). Baclofen can be helpful for PAN, and therapy was initiated in this particular patient with mild improvement. She also had hypermetric saccades, saccadic smooth pursuit and vestibulo-ocular reflex suppression, gaze-evoked nystagmus, as well as a cross-coupled response with head-shaking - i.e., with horizontal head-shaking, vertical nystagmus (downbeating) was apparent). This is another central vestibular/ocular motor sign, and can also be seen with nodulus/uvula pathology as well as with flocculus/paraflocculus involvement - this finding can be seen at the end of the video. This patient had a pan-cerebellar syndrome involving the vestibulocerebellum as well as the fastigial nucleus (saccadic hypermetria) and other regions. https://collections.lib.utah.edu/ark:/87278/ s62k013r