Downbeat nystagmus caused by hypomagnesemia : A case report

Abstract

We report a case of downbeat nystagmus (DBN) and tremor in a patient who visited our hospital 6 months after the onset of dizziness. Hypomagnesemia was considered as a possible cause based on the results of a serum magnesium examination. Intravenous magnesium sulfate was therefore administered to correct the patient's serum magnesium level. The DBN and tremor almost completely disappeared the following day. Although there have been several case reports of dizziness in association with hypomagnesemia, the authors did not mention DBN. This report is considered to be the first DBN case caused by hypomagnesemia in Japan. Cases of hypomagnesemia, which may be induced by several factors－including excessive diet, long-term proton-pump inhibitor (PPI) intake, and type 2 diabetes－are increasing. In cases of DBN, a serum magnesium examination is as important as head MRI.