Spontaneous Torsional Nystagmus and Ocular Tilt Reaction

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a 70-year-old man who experienced "a delay in focusing" with "some twisting movement" that began about 18 months prior to this video with mild progression over days or weeks. For the same period of time, he experienced intermittent vertical diplopia. MRI done months after the onset was unremarkable, as was a second contrast-enhanced MRI done several months prior to this video. Evaluation for neoplastic/paraneoplastic, infectious, inflammatory, autoimmune disorders was unrevealing and his symptoms had been subjectively stable for over a year. Discussions about possible genetic testing (e.g., spinocerebellar ataxias) is ongoing. Oscillopsia - There was spontaneous torsional nystagmus (top poles beating toward the right ear) in primary gaze with a very slight downbeat (DB) component. The torsional nystagmus is unidirectional in all directions of gaze, although there was more DB in right gaze. Gabapentin or baclofen trial was discussed and deferred given the mild nature of his oscillopsia (mainly experienced in right gaze). Diplopia - There was a small-angle right hypertropia of 1 PD in primary gaze that measured 2 PD in right gaze and was otherwise comitant on 3-step testing. Ocular counterroll (OCR, top poles toward the left ear) was present on fundus photos, and with bucket test, there was a 5 degree leftward tilt in subjective visual vertical (SVV). Taken together, he had evidence of a partial ocular tilt reaction (OTR) including skew deviation, OCR, and SVV (a perceptual consequence of the OTR), but without a noticeable static head tilt. The slow phase of his torsional nystagmus caused the top poles to rotate toward the left ear, which was also in the direction of the OCR from his partial OTR - therefore, imbalance in the utricle-ocular motor pathways explained his OTR and could be an explanation for his torsional nystagmus as well (no clear jerky or hemi-seesaw nystagmus was seen). Or, in addition to central utricle pathway damage, fairly symmetric central damage to posterior and anterior semicircular pathways could be responsible for his mainly torsional nystagmus. Otherwise, there were no other neuro-ophthalmic or neurologic signs to suggest a lesion in the lateral medulla, medial longitudinal fasciculus or interstitial nucleus of Cajal (any of which could cause OTR and spontaneous torsional or vertical-torsional nystagmus). 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This patient experienced "a delay in focusing" with "some twisting movement" that began about 18 months prior to this video with mild progression over days or weeks. For the same period of time, he experienced intermittent vertical diplopia. MRI done months after the onset was unremarkable, as was a second contrast-enhanced MRI done several months prior to this video. Evaluation for neoplastic/paraneoplastic, infectious, inflammatory, autoimmune disorders was unrevealing and his symptoms had been subjectively stable for over a year. Oscillopsia - There was spontaneous torsional nystagmus (top poles beating toward the right ear) in primary gaze with a very slight downbeat (DB) component. The torsional nystagmus is unidirectional in all directions of gaze, although there was more DB in right gaze. Gabapentin or baclofen trial was discussed and deferred given the mild nature of his oscillopsia (mainly experienced in right gaze). Diplopia - There was a small-angle right hypertropia of 1 PD in primary gaze that measured 2 PD in right gaze and was otherwise comitant on 3-step testing. Ocular counterroll (OCR, top poles toward the left ear) was present on fundus photos, and with bucket test, there was a 5 degree leftward tilt in subjective visual vertical (SVV). Taken together, he had evidence of a partial ocular tilt reaction (OTR) including skew deviation, OCR, and SVV (a perceptual consequence of the OTR), but without a noticeable static head tilt. The slow phase of his torsional nystagmus caused the top poles to rotate toward the left ear, which was also in the direction of the OCR from his partial OTR - therefore, imbalance in the utricle-ocular motor pathways explained his OTR and could be an explanation for his torsional nystagmus as well (no clear jerky or hemi-seesaw nystagmus was seen). Or, in addition to central utricle pathway damage, fairly symmetric central damage to posterior and anterior semicircular pathways could be responsible for his mainly torsional nystagmus. Otherwise, there were no other neuro-ophthalmic or neurologic signs to suggest a lesion in the lateral medulla, medial longitudinal fasciculus or interstitial nucleus of Cajal (any of which could cause OTR and spontaneous torsional or vertical-torsional nystagmus). https://collections.lib.utah.edu/ark:/87278/s6vt71tc