Severe hypomagnesemia associated with reversible subacute ataxia and cerebellar hyperintensities on MRI

Hypomagnesemia has been associated with various neurological symptoms including ataxia. Reversible changes in cerebellar function have been described due to hypertensive changes, eclampsia, and immunosuppressive therapy in the context of posterior reversible encephalopathy syndrome. In this report we document isolated, reversible cerebellar findings with the corresponding neuroimaging correlates associated with critically low magnesium levels.

A 72-year-old male with metastatic colorectal cancer and short gut syndrome presented with subacute ataxia and cerebellar T2 hyperintensities on magnetic resonance imaging. The patient showed rapid clinical and radiologic improvement in his cerebellar findings after receiving only magnesium supplementation.

Our report suggests that low magnesium levels may mimic the vascular endothelial dysregulation that is seen in the context of rapid rises in blood pressure in both posterior reversible encephalopathy syndrome and eclampsia. This rare case suggests a potential role of magnesium in stabilizing the vascular endothelium and, when deficient, in contributing to cerebral edema of the posterior circulation territories.