Kazumitsu Amari1, Yosuke Kudo2, Kosuke Watanabe2, Masahiro Yamamoto2, Koji Takahashi3, Osamu Tanaka3, Ken Johkura4. 1. Department of Neuroendovascular Therapy, Yokohama Brain and Spine Center, Yokohama, Japan. 2. Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan. 3. Department of Clinical Laboratory, Yokohama Brain and Spine Center, Yokohama, Japan. 4. Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan. Electronic address: ke00-johkura@city.yokohama.jp.
Abstract
BACKGROUND AND PURPOSE: Lateral medullary infarction (LMI) sometimes causes long-lasting dizziness. However, the characteristics of nystagmus in patients with post-LMI dizziness are unknown. We undertook a prospective, comparative study of nystagmus in patients with and without post-LMI dizziness to determine the characteristic pattern of nystagmus of chronic post-LMI dizziness. METHODS: We evaluated and compared nystagmus under spontaneous, head-shaking, and positional testing conditions in 12 patients with post-LMI dizziness and in 6 patients without post-LMI dizziness. RESULTS: In the dizziness group, contralateral spontaneous nystagmus, ipsilateral head-shaking nystagmus, and horizontal direction-changing geotropic positional nystagmus were observed in patients in whom the LMI had occurred <60days previously (subacute period). In patients with dizziness in whom the LMI had occurred >90days previously (chronic period), the nystagmus was ipsilateral under all conditions. In the non-dizziness group, ipsilateral nystagmus was observed in 1 of the 2 subacute patients only after head-shaking and in 1 of the 4 chronic patients only during positional testing. CONCLUSIONS: Ipsilateral nystagmus observed under all spontaneous, head-shaking, and positional testing conditions characterizes chronic post-LMI dizziness.
BACKGROUND AND PURPOSE: Lateral medullary infarction (LMI) sometimes causes long-lasting dizziness. However, the characteristics of nystagmus in patients with post-LMIdizziness are unknown. We undertook a prospective, comparative study of nystagmus in patients with and without post-LMIdizziness to determine the characteristic pattern of nystagmus of chronic post-LMI dizziness. METHODS: We evaluated and compared nystagmus under spontaneous, head-shaking, and positional testing conditions in 12 patients with post-LMIdizziness and in 6 patients without post-LMIdizziness. RESULTS: In the dizziness group, contralateral spontaneous nystagmus, ipsilateral head-shaking nystagmus, and horizontal direction-changing geotropic positional nystagmus were observed in patients in whom the LMI had occurred <60days previously (subacute period). In patients with dizziness in whom the LMI had occurred >90days previously (chronic period), the nystagmus was ipsilateral under all conditions. In the non-dizziness group, ipsilateral nystagmus was observed in 1 of the 2 subacute patients only after head-shaking and in 1 of the 4 chronic patients only during positional testing. CONCLUSIONS:Ipsilateral nystagmus observed under all spontaneous, head-shaking, and positional testing conditions characterizes chronic post-LMIdizziness.