waves with higher frequencies (0.3-4°, 0.3-1.5 cycles/second), which were superimposed on the lager amplitude and low frequency pendular oscillations (3.7-13°, 0.05-0.2 cycles/second, Fig). Without fixation, he showed subtle left beating nystagmus and minimal oscillation of the right eye. He showed an impaired convergence on attempted viewing a near target, probably due to the inability to fuse. Video-oculographic recording of the horizontal smooth pursuit also documented bilateral impairments. However, horizontal and vertical saccades were normal. Other findings of neurological examination were normal. He showed abnormal extorsion of the right eye (15.6- 24.8°, normal range: 0-12.6°), which worsened in downward gaze. Thyroid function tests, serum anti-acetylcholine antibody titer, and brain MRI were normal.