Mild encephalitis/encephalopathy with a reversible splenial lesion in children

Abstract

Purpose: We aimed to present clinical and radiologic characteristics of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) in children.

Methods: Eight children (5 boys and 3 girls; median age, 5.9 years; age range, 8 months to 14.1 years) diagnosed with MERS between September 2015 and June 2017 were included in the study. We reviewed the patient's data, including demographic characteristics, prodromal and neurologic symptoms, neurologic examination, magnetic resonance imaging and electroencephalography findings, laboratory findings, treatment, and prognosis.

Results: Prodromal symptoms were nausea and vomiting (n=6), diarrhea (n=6), and fever (n=3). Initial neurologic symptoms were seizures (n=4), delirious behavior (n=1), drowsiness (n=1), ataxia (n=1), transient blindness (n=2), abnormal speech (n=2), and headache (n=1). Two patients had a suspected infective agent: urinary tract infection caused by Escherichia coli and gastroenteritis caused by rotavirus. Seven patients had type I lesions, comprising characteristic symmetric ovoid (n=6) and band-shaped (n=1) T2-weighted hyperintense lesions at the spenium of corpus callosum, and one patient had type II lesion with additional symmetric posterior periventricular lesions. The lesions were isointense to mildly hypointense on T1-weighted imaging and did not show enhancement. All lesions displayed restricted diffusion. In all patients, neurologic symptoms completely normalized < 48 hours from the onset of symptoms without any sequelae.

Conclusion: MERS has characteristic imaging features and favorable outcome.

Figure 1. a–d

A 7-year-old male presented with delirium and speech abnormality after vomiting and diarrhea. His first brain MRI showed central ovoid lesion at splenium of corpus callosum (arrows) (type I). Lesion was slightly hyperintense on T2-weighted image (a), hyperintense on diffusion-weighted image (b) and hypointense on ADC map related to diffusion restriction (c). Follow-up MRI showed complete resolution of the lesion on diffusion-weighted image (d).

Figure 2. a–c

A three and a half years old male presented with seizure after vomiting and diarrhea. His first brain MRI showed band-shaped lesion at splenium of corpus callosum (arrows) (type I). Lesion was slightly hyperintense on T2-weighted image (a), hyperintense on diffusion-weighted image (b) and hypointense on ADC map related to diffusion restriction (c). Follow-up MRI was not performed.

Figure 3. a–d

A 6-year-old male presented with speech abnormality and seizure. His first brain MRI showed symmetric posterior periventricular lesions in addition to splenial lesion (arrows) (type II). Lesion was slightly hyperintense on T2-weighted image (a), hyperintense on diffusion-weighted image (b) and hypointense on ADC map related to diffusion restriction (c). Follow-up MRI showed complete resolution of the lesion on diffusion-weighted image (d).