随意的に制御可能な先天性眼振の1例

抄録

We report an unusual case of congenital nystagmus in a patient who could both suppress and release her nystagmus at will. A 37-year-old woman complained of blurred vision on right lateral gaze. Initially, she had pendular nystagmus only on right lateral gaze. Nystagmus was considered congenital, because the patient showed unilateral inversion of OKN, the wave form of nystagmus coincided with the asymmetric pendular type of Dell'Osso's classification and no gaze-dependent nystagmus was observed with closed eyes. On follow up, nystagmus also appeared on left lateral gaze and downward gaze. Furthermore, she acquired the ability to control her nystagmus, starting and stopping voluntarily. She could stop her nystagmus by taking the eye position for near fixation. ENG showed left monocular adduction when she stopped her nystagmus. To release the nystagmus, she appeared to focus at a distance with vacant eyes. However, the patient did not show spontaneous nystagmus in the dark, so we speculated that some visual input was needed for the release of nystagmus.