Mumps-virus-associated Clinically Mild Encephalopathy With a Reversible Splenial Lesion

Mumps virus infection primarily involves the parotid glands and most frequently affects young children during the winter and spring months. It is known that mumps virus infection may be accompanied by neurological manifestations, including meningitis and encephalitis. However, few cases of acute encephalopathy have been reported to date. We report a case of a 4-year-old girl with clinically mild encephalopathy with a reversible splenial lesion associated with mumps virus infection. She had swelling of the bilateral parotid glands. She was admitted to our hospital because of reduced level of consciousness, seizures, and vomiting. Cell counts in the cerebrospinal fluid (CSF) were normal. She had a low serum sodium level on admission. Brain computed tomography showed mild cerebral edema. Electroencephalography showed partial high-voltage slow waves at the occipital lesion, and diffusion-weighted magnetic resonance imaging demonstrated a transient abnormality in the splenium of the corpus callosum. We diagnosed clinically mild encephalopathy with a reversible splenial lesion associated with mumps virus infection. She recovered well, and exhibited no neurological sequelae. Mumps virus RNA was not detected in the CSF, suggesting that the reversible splenial change was caused by indirect effects on the central nervous system subsequent to viral infection. Her low serum sodium level also indicates that this change can occur with hyponatremia. doi: http://dx.doi.org/10.4021/ijcp51w