Extrapontine myelinolysis caused by electrolyte imbalance during the management of suprasellar germ cell tumors. Report of two cases.

Extrapontine myelinolysis (EPM) is caused by marked fluctuation of the serum electrolyte level. Patients with suprasellar germ cell tumors frequently present with diabetes insipidus, which is often aggravated by administration of steroid hormone. In addition, cisplatin-based chemotherapy is sometimes accompanied by marked serum electrolyte fluctuation because it needs massive hydration to prevent renal damage. Two children with suprasellar germ cell tumors in whom EPM developed secondary to profound hyponatremia and was rapidly corrected are described. The central pons was spared in both cases. Clinically the children showed transient neurological deficits including confusion, pseudobulbar palsy, and deterioration of consciousness. MRI demonstrated bilateral symmetrical, high-signal-intensity (HSI) lesions on T2-weighted images (T2WI) at the basal ganglia and adjacent cerebral cortex. Follow-up T1WI a few months later revealed newly developed HSI lesions in the basal ganglia. The patients gradually improved, but the neurological deficits did not completely disappear. During the perioperative management of suprasellar germ cell tumors, EPM should be considered when a patient has a significant electrolyte imbalance and neurological deficits, especially confusion and pseudobulbar palsy.