New-onset Oscillopsia in a Patient With a History of Pontine Stroke

A 69-year-old man with a history of pontine hemorrhage 2 years ago noticed binocular vertical diplopia after the stroke. On examination, there was a small-angle incomitant left hyperdeviation that did not fit the 3-step test for fourth nerve palsy and incyclotorsion of the higher eye. On motility testing, there was an obvious pendular nystagmus. Resting tremor of the right hand was noticed on neurological examination. Examination of the oropharynx revealed rhythmic oscillations of the soft palate synchronous with the eye oscillations and hand tremor. These findings established a diagnosis of oculopalatal myoclonus (OPM). Although OPM is a well-described entity, this case is unique because the patient was completely asymptomatic from OPM and did not complain of oscillopsia but was very bothered by vertical diplopia because of skew deviation. It also demonstrates that OPM may coexist with skew deviation because anatomically vestibulo-ocular pathway is close to the triangle of Guillain-Mollaret and patients with lesions in one pathway should be examined for abnormalities in the other. Finally, it reminds us about the importance of monitoring patients with a history of brainstem insults for emergence of synchronous tremors years later and that simple maneuver-like ex/amining oropharynx may provide a clear diagnosis.