Cerebellar Syndrome Induced by Hypomagnesemia: A Treatable Cause of Ataxia Not to be Missed. Report of Three Cases and a Review of the Literature.

Background: Magnesium is an important intracellular cation involved in essential enzymatic reactions. It is necessary for neuronal function and its depletion can produce neurological symptoms such as cramps or seizures. Clinical consequences of its deficit in the cerebellum are less known and the diagnosis can be delayed because of the lack of awareness on this condition.

Cases: We present three cases of cerebellar syndrome (CS) due to hypomagnesemia: A midline CS with myoclonus and ocular flutter and two cases of hemispheric CS, one of them entailed a Schmahmann's syndrome and the other suffered a seizure. MRI findings revealed cerebellar vasogenic edema and the symptoms improved after magnesium replacement in all cases.

Literature Review: We reviewed 22 cases of CS due to hypomagnesemia, all with subacute onset (days to weeks). Encephalopathy and/or epileptic seizures were common. MRI findings were vasogenic edema involving the cerebellar hemispheres, the vermis, or the nodule. Up to 50% of patients presented hypocalcemia and/or hypokalemia. All the patients showed symptomatic improvement after magnesium replacement, but 50% showed significant sequelae, and 46% relapsed.

Conclusions: Hypomagnesaemia should always be considered in the differential diagnosis of CS as it has a potential treatment, and its early recognition can avoid recurrences and permanent cerebellar impairment.