A Rare Association of Hypomagnesemia and Posterior Reversible Encephalopathy Syndrome (PRES)

Posterior reversible encephalopathy syndrome (PRES) is a rare neurologic disorder that presents with variable symptoms and symmetrical abnormal white matter signaling most commonly of the occipital and parietal lobes on magnetic resonance imaging (MRI). PRES, also known as reversible posterior leukoencephalopathy syndrome (RPLS) is commonly associated with hypertension. Hypomagnesemia’s association with PRES has been rarely reported. Here, we report a patient with severe hypomagnesemia that presented with PRES syndrome that improved with magnesium replacement. Hypomagnesemia should be considered an underlying etiology in patients presenting with PRES syndrome and should be promptly treated. The presentation can often be concerning for acute cerebrovascular accidents with symptoms of dysarthria and upper motor neuron symptoms, such as facial droop, dysarthria, and gait instability. Differential diagnosis of PRES often includes rostral brainstem infarction, transient ischemic attack, infectious encephalopathy, and metabolic/toxic encephalopathy, which is evaluated in the description of the case. The most common presentation of RPLS/PRES includes altered mental status, drowsiness, seizure, vomiting, alterations in speech including dysarthria, and visual disturbance. The first signs noted are commonly lethargy and somnolence. In this case, the patient presented notably with initial symptoms of dysarthria of speech and facial droop, with serum hypomagnesemia in which symptoms corrected rapidly with the administration of intravenous magnesium sulfate.