Oculopalatal Tremor and One-and-a-Half Syndrome Due to Pontine Hemorrhage

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a 65-year-old man who was put on a blood thinner, and shortly thereafter experienced a midline pontine hemorrhage, which was more dense on the left side. Immediately afterwards, right hemiparesis and hemi-anesthesia, left lower motor neuron (LMN) facial palsy and ophthalmoparesis were noted. Months later, he experienced oscillopsia as well. At the time that this video was taken, he was about 6 months from the pontine hemorrhage. There was mainly vertical pendular nystagmus noted in the left eye, and there were vertical and horizontal (convergent-divergent) components in the right eye, along with palatal tremor, which is known as oculopalatal tremor (OPT). Vertical movements were normal and horizontal motility exam demonstrated a left internuclear ophthalmoplegia (INO -damage to the left medial longitudinal fasciculus [MLF]) and left horizontal gaze palsy (damage to left 6th nucleus affecting fibers destined for left lateral rectus and interneurons destined for right medial rectus via right MLF), and a partial right 6th nerve palsy, related to injury of the right 6th fascicle. The combination of left INO and left horizontal gaze palsy is also referred to as a one-and-a-half syndrome. Disjunctive nystagmus is common in OPT, and given the proximity of the descending central tegmental tract (CTT) to the fascicle/nucleus of CN6 and MLF, horizontal motility deficits may cause disjunctive horizontal components as in this patient who couldn't adduct or abduct OS (i.e., nystagmus was pure vertical OS). Typically, pendular nystagmus in OPT is vertical, torsional, or vertical-torsional, although there may be horizontal components as well, sometimes with a convergent-divergent pattern. Review of a recently obtained MRI showed hyperintensity of the left inferior olive (IO) on MRI T2/FLAIR sequences due to hypertropic olivary degeneration (HOD). In his case, HOD was related to injury of the descending central tegmental tract (CTT) as it passed through the pons, thereby removing normal inhibition of the IO by the CTT (https://collections.lib.utah.edu/details?id=1278831). 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This patient suffered a midline pontine hemorrhage (left>right) shortly after being put on a blood thinner. Immediately afterwards, right hemiparesis and hemi-anesthesia, left lower motor neuron (LMN) facial palsy and ophthalmoparesis were noted. Months later, he experienced oscillopsia as well. At the time that this video was taken, he was about 6 months from the pontine hemorrhage. There was mainly vertical pendular nystagmus noted in the left eye, and there were vertical and horizontal (convergent-divergent) components in the right eye, along with palatal tremor, which is known as oculopalatal tremor (OPT). Vertical movements were normal and horizontal motility exam demonstrated a left internuclear ophthalmoplegia (INO -damage to the left medial longitudinal fasciculus [MLF]) and left horizontal gaze palsy (damage to left 6th nucleus affecting fibers destined for left lateral rectus and interneurons destined for right medial rectus via right MLF), and a partial right 6th nerve palsy, related to injury of the right 6th fascicle. The combination of left INO and left horizontal gaze palsy is also referred to as a one-and-a-half syndrome. Disjunctive nystagmus is common in OPT, and given the proximity of the descending central tegmental tract (CTT) to the fascicle/nucleus of CN6 and MLF, horizontal motility deficits may cause disjunctive horizontal components as in this patient who couldn't adduct or abduct OS (i.e., nystagmus was pure vertical OS). Typically, pendular nystagmus in OPT is vertical, torsional, or vertical-torsional, although there may be horizontal components as well, sometimes with a convergent-divergent pattern. Review of a recently obtained MRI showed hyperintensity of the left inferior olive (IO) on MRI T2/FLAIR sequences due to hypertropic olivary degeneration (HOD). In his case, HOD was related to injury of the descending central tegmental tract (CTT) as it passed through the pons, thereby removing normal inhibition of the IO by the CTT. (Video and legend created with the assistance of Dr. Tony Brune) https://collections.lib.utah.edu/ark:/87278/s6wh6sfc