Extrapontine Myelinolysis following Extreme Hypernatremia and Hyperosmolarity

Abstract

We present a case of a nearly 3-year-old girl who was admitted to hospital due to severe hypernatremia (196 mmol/l). Her medical history included central hypothyreosis and growth hormone deficiency. Rehydration and normalization of sodium was achieved according to guidelines. On the fourth day of hospitalization, the patient developed tremor, ataxia, and rigor. Cranial magnetic resonance imaging (cMRI) was performed and (mis)interpreted for meningoencephalitis, with corresponding diagnostic and therapeutic implications. The patient had extrapontine myelinolysis. The child recovered completely after hospitalization for nearly 2 weeks.

Figure 1

Sodium values over the course of hospitalization (in mmol/l, reference range 136–146 mmol/l).

Figure 2

DWI—bilateral diffusion impairment in the basal ganglia, corpus callosum, and subcortical regions with slightly dilated lateral ventricles.

Figure 3

T2-FLAIR—discrete signal modulation in the corresponding T2-FLAIR sequence.

Figure 4

T2-FLAIR—unremarkable pons.