Oculopalatal Tremor with Prominent Nystagmus, Bilateral Horizontal Gaze Palsy, and Bilateral Facial Palsies (Figure 1)

Figure 1, MRI T2 sequence demonstrating hyperintensities involving bilateral inferior olives of the medulla. This is a 50-year-old woman who experienced the acute onset of right sixth and seventh nerve palsies and left hemiparesis. Two cavernomas within the right pons (one in the region of the facial colliculus) were demonstrated by MRI. Five years after her initial presentation she developed recurrent right facial palsy and dysphagia. Imaging revealed acute pontine hemorrhage and she underwent surgical resection of the cavernoma. Post-operatively, she had facial diplegia and bilateral horizontal gaze palsies. Several months later, she experienced vertical oscillopsia. On examination, she had continuous large amplitude vertical pendular nystagmus and symmetric palatal myoclonus. She had bilateral horizontal gaze palsies with intact vertical movements. Convergence increased her ability to adduct OU slightly. Review of her MRI two months post-operatively revealed surgical changes to the floor of the fourth ventricle as well as marked hyperintensities of the bilateral inferior olivary nuclei. This patient presented with classic features of oculopalatal tremor (OPT), including vertical pendular nystagmus, palatal myoclonus, and MRI evidence of inferior (medullary) olivary hypertrophy. Given the proximity of the central tegmental tract to the abducens nuclei and facial nerve fascicles, she also had horizontal gaze palsy and facial diplegia. OPT develops weeks to months following an injury to the Guillain-Mollaret triangle, which is an imaginary triangle connecting the inferior olive of the medulla to the contralateral dentate nucleus of the cerebellum, with fibers then travelling from the dentate to the contralateral red nucleus (fibers wrap around the red nucleus) of the midbrain, and these fibers descend the central tegmental tract to synapse on the ipsilateral inferior olive. Increased (and synchronous) transmission via gap junctions between olivary neurons and maladaptive cerebellar changes have been implicated in generating OPT. Treatment options for her pendular nystagmus include gabapentin or memantine. [[See video case: https://collections.lib.utah.edu/details?id=1290929 ]]