# Horizontal Pendular Nystagmus and Ataxia Secondary to Severe Hypomagnesemia

## TL;DR

This paper presents a case of horizontal pendular nystagmus and ataxia caused by severe low magnesium levels, highlighting a rare neurological manifestation.

## Contribution

The paper reports a novel association between severe hypomagnesemia and horizontal pendular nystagmus.

## Key findings

- Horizontal pendular nystagmus was observed in a patient with acute cerebellar ataxia due to severe hypomagnesemia.
- Pendular nystagmus in this case was distinguished from ocular flutter and macrosaccadic oscillations by its slow phase characteristics.
- This is the first reported case linking severe hypomagnesemia with pendular nystagmus.

## Abstract

Severe hypomagnesemia is an increasingly recognized cause of acute and reversible cerebellar ataxia, often accompanied by cerebellar oculomotor signs such as jerky horizontal or downbeat nystagmus and very rarely ocular flutter.

This video illustrates horizontal pendular nystagmus in a patient with acute onset cerebellar ataxia associated with severe hypomagnesemia.

Acquired pendular nystagmus can be distinguished from macrosaccadic oscillations and ocular flutter in that the former is composed of two slow phases of equal velocity and the latter of two fast phases of saccadic type with or without intersaccadic interval, respectively. It is most commonly associated with demyelinating, toxic, metabolic, and genetic disorders, but has not been reported in association with severe hypomagnesemia.