橋出血後に出現した ocular myoclonus 例

The patient, a 65-year-old man who presented with a history of dizziness 2 years after suffering a pontine hemorrhage, was referred to our department for a thorough examination. Examination of the nystagmus revealed pendulum-like eye movements, regardless of the gaze or head position. A head CT obtained at the time of the pontine hemorrhage showed a high-density area almost in the pontine midline, and T1-weighted MRI showed a high-intensity area in the periphery and a low-intensity area within the same area. Because of the development of abnormal eye movements 2 years after the pontine hemorrhage, we suspected ocular myoclonus and performed electro-oculography, pharyngolaryngoscopy, and MRI. Electrooculography showed pendulum-like eye movements with both horizontal and vertical components. Pharyngolaryngoscopy revealed myoclonus of the soft palate and larynx synchronized with the rhythm of the eye movements. T2-weighted MRI showed a high-signal area to the right of the medulla oblongata that was not seen in the images obtained two years earlier, and enlargement of the right anterior medulla oblongata, and we considered the possibility of hypertrophic olivary degeneration. Considering the MRI findings along with the finding of abnormal eye movements with myoclonus in multiple areas synchronized with the eye movements developing after pontine hemorrhage, we diagnosed the patient as having ocular myoclonus. We initiated treatment with clonazepam and gabapentin, but the abnormal eye movements and subjective symptoms failed to improve. The symptoms showed neither improvement nor worsening until 3 years later, and the follow-up was terminated. Ocular myoclonus, a type of abnormal ocular oscillation, is a 1.5- to 5-Hz vertical eye movement that presents as a sustained periodic pendulum-like oscillation of the eye and includes horizontal and rotatory components. It is often accompanied by myoclonus of the soft palate and may be accompanied by extensive involuntary movements of the tongue, facial muscles, pharynx, larynx, and diaphragm. It usually appears after a latency of 2–48 months after brainstem or cerebellar hemorrhage.