Peculiar venous lesions in fatal hyponatremic brain edema.

A 19-year-old woman with a 3-year history of schizophrenia suddenly began to vomit, and rapidly developed a coma an hour after the onset of vomiting. A brain CT scan showed diffuse brain edema with compression of the ventricles. Laboratory tests showed a low serum sodium concentration of 117 mmol/L. She died 67 h after the onset of the first symptom. A postmortem examination showed diffuse swelling of the brain with bilateral uncal and tonsillar herniations. Histologically, no necrotic, hemorrhagic or encephalitic changes were seen. However, microvacuolar changes with lymphocytic infiltration were found in the venous walls (media and adventitia) mainly in the basal ganglia, thalamus and brainstem. To our knowledge, this is the first demonstration of venous alterations in fatal hyponatremic brain edema. These changes may have participated in the exacerbation of the brain edema due to functional disturbance of venous drainage.