Description

A 52-year-old woman with mental retardation and diabetes mellitus was hospitalized for a bronchial asthma attack. As the wheezing subsided with dexamethasone, empagliflozin was restarted on the second day, leading to polyuria and an increase in serum sodium to 191 mEq/L by the fourth day. Following discontinuation of empagliflozin, her Na level dropped to 145 mEq/L by the 11th day, but she remained unsteady. On the 13th day, a head Magnetic Resonance Imaging (MRI) showed high-signal areas in the middle cerebellar peduncles on diffusion-weighted images and disappearance of cerebral sulci on fluid-attenuated inversion recovery, suggesting cerebral edema due to hypernatremia correction (Figure 1). Her symptoms improved with rehabilitation, and a repeat MRI on the 30th day showed resolution (Figure 2). In adults, it is generally recommended that hypernatremia correction should not exceed 12 mEq/L per day [1]. However, this guideline is derived from observational studies in infants and children, with limited direct evidence in adults. Reports suggest that even when sodium levels are corrected faster than 12 mEq/L per day in adults, no consistent associations with mortality, seizures, altered consciousness, or cerebral edema have been observed [2]. Nevertheless, slow correction of hypernatremia in adults may be prudent to minimize potential risks.

Figure 1: (A) Diffusion-weighted Magnetic Resonance Imaging (MRI) of the head shows high-signal areas in the middle cerebellar peduncles (yellow arrows). (B) On the fluid-Attenuated Inversion Recovery (FLAIR) sequence of the head MRI, a disappearance of the cerebral sulci is observed (small yellow arrows).

Figure 2: (A) The high-signal areas in the middle cerebellar peduncles observed on diffusion-weighted MRI of the head have disappeared. (B) The sulci that had disappeared on the FLAIR image of the head MRI normalized, suggesting an improvement in brain edema.

References

1. Kim SW. Hypernatemia: Successful treatment. Electrolyte Blood Press. 2006; 4: 66-71.
2. Chauhan K, Pattharanitima P, Patel N, et al. Rate of Correction of Hypernatremia and Health Outcomes in Critically Ill Patients. Clin J Am Soc Nephrol 2019; 14: 656-63.