PMC1351204_01
Representative record of downbeat nystagmus in Patient 1, which increased with convergence. Positive values indicated rightward, upward, or convergence movements.
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F1
Eye movement measurements confirmed downbeat nystagmus, which increased on lateral and down gaze, following head shaking (especially vertically) and during convergence (Fig. 1).
PMC1351204_02
MRI brain of patient 2 showing atrophy of cerebellum.
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F2
MRI of the brain and cervical spinal cord revealed mild atrophy of the cerebellum, particularly the superior aspects of the vermis (Fig. 2), and mild atrophy of the upper cervical cord.
Representative record from Patient 2, showing downbeat nystagmus on left-gaze and a burst of horizontal saccadic oscillations. On the inset at right, the saccadic oscillations are shown at a different time scale; note that an intersaccadic interval (marked by asterisk) is present for some, but not all, cycles. Same conventions as in Figure 1.
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F3
Eye movement measurements confirmed that she had downbeat nystagmus on lateral and downgaze (Fig. 3), but this did not increase with convergence, or after head shaking. In addition, she showed intermittent horizontal saccadic oscillations, occurring in bursts, at a frequency of about 5-6 Hz; brief intersaccadic intervals could be discerned for some, but not all, oscillation cycles (subplot in Fig. 3).