The analysis of up and down-beating nystagmus on electronystagmography

Up-and down-beating nystagmus reminds us of central vestibular deficits, such as spino-cerebellar degeneration and Arnold-Chiari malformation. However, in our routine medical care, we frequently meet cases with vertical nystagmus, which are finally diagnosed as being a certain peripheral vestibular deficit. In this manuscript, we studied the medical records of cases visiting our neuro-otological specialty outpatient clinic since January 2011 to April 2015 (1,770 cases), and detected patients who exhibited vertical nystagmus in ENG recordings (58 cases). Detailed diagnosis, clinical findings including VOG recordings, and the course of the nystagmus were verified. These consisted of 27 with central deficits, 18 with peripheral deficits, accompanied by 2 with vestibular schwannomas and 11 without a confirmed diagnosis. Eighteen cases demonstrated vertical nystagmus on ENG, reconfirmed with VOG recordings in their clinical courses, which included 6 with peripheral deficits. Findings of several cases support an inclusion of a rotational component of nystagmus, which was interpreted as vertical on ENG. On the other hand, in some cases, possible pure-vertical nystagmus caused by a peripheral vestibular deficit was also suggested.