Jerk Nystagmus

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is an example of jerk nystagmus due to a central vestibular lesion. The slow phase is the pathologic phase (to the left) which initiates the movement, and is followed by a fast position reset mechanism (to the right). Jerk nystagmus is named after the fast phase. This patient presented with the acute vestibular syn- drome due to a demyelinating brainstem lesion, which led to the diagnosis of neuromyelitis optica. She has spontaneous right-beating nystagmus (RBN), that stays unidirectional (RB) in all directions of gaze, even to the left. To the right, there is more intense RBN in accordance with Alexander's law (i.e., vestibular nystagmus will increase in the direction of the fast fast.) 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This is an example of jerk nystagmus due to a central vestibular lesion. The slow phase is the pathologic phase (to the left) which initiates the movement, and is followed by a fast position reset mechanism (to the right). Jerk nystagmus is named after the fast phase. This patient presented with the acute vestibular syndrome due to a demyelinating brainstem lesion, which led to the diagnosis of neuromyelitis optica. She has spontaneous right-beating nystagmus (RBN), that stays unidirectional (RB) in all directions of gaze, even to the left. To the right, there is more intense RBN in accordance with Alexander's law (i.e., vestibular nystagmus will increase in the direction of the fast fast)