Streptococcus pneumoniae is a common cause of bacterial meningitis, frequently leading to death or severe neurological impairment. We report an exceptional case of a 7-month-old child with meningoencephalitis caused by S. pneumoniae. Peculiar, widespread and unique signal abnormalities were found on magnetic resonance imaging (MRI) with extensive central nervous white matter injury as well as evidence of thrombosis of the lateral transverse sinus. These changes were observed very early in the course of the illness, presumably reflecting widespread cytotoxic edema, vasculitis and acute demyelination. These lesions occurred despite appropriate antibiotic and anti-inflammatory (glucocorticoid) therapy started very early in the course of the disease. Such diffuse white matter lesions in the early course of (pediatric) cases of S. pneumoniae meningoencephalitis have not been reported previously.