Acute necrotizing encephalopathy in Korean infants and children: imaging findings and diverse clinical outcome

Abstract

Objective: The purpose of our study was to describe acute necrotizing encephalopathy in Korean infants and children, and we sought to evaluate the prognostic factors.

Materials and methods: Acute necrotizing encephalopathy was diagnosed in 14 Korean infants and children. We retrospectively analyzed the neuroimaging findings including the follow-up changes. The clinical course of the disease was graded, and we evaluated prognostic factors including age, serum level of the aminotransferase, hemorrhage, and localized atrophy of the brain.

Result: This encephalopathy predominantly affected the bilateral thalami (n = 14), pons (n = 12), and midbrain (n = 10) in a symmetrical pattern. Hemorrhage was observed in eight patients (57%). On the follow-up images (n = 12), the brain lesions were reduced in extent for all patients, and generalized atrophy was seen in six patients. Localized tissue loss was observed in five patients and a complete resolution occurred for one patient. All the patients survived and two recovered completely; mild (n = 6) to severe (n = 6) neurological deficits persisted in the remaining 12 patients. The significant prognostic factors identified in this study were the presence of hemorrhage (p = 0.009) and localized atrophy (p = 0.015).

Conclusion: Acute necrotizing encephalopathy in Korean patients showed the characteristic patterns of the post-infectious encephalopathy as described in the literature. The high survival rate and the relatively favorable clinical course observed for the present study suggest a more diverse spectrum of disease severity than was previously described. The presence of hemorrhage and localized tissue loss on MR images may suggest a poor prognosis.

Fig. 1

MRIs of a 10-month-old girl (patient 4) who was left with severe sequelae. A, B. Initial MR images obtained on the day following the hospital admission. T2-weighted axial images (A, B) show increased signal intensity in the thalami, the posterior internal capsule, putamen, periventricular white matter and the tegmen of the pons (arrows). C, D. Follow-up MR images obtained after one month of initial study. The T1-weighted image (C) shows shrunken thalami, localized low signal intensity that was similar to the cerebrospinal fluid in the periventricular white matter, and generalized atrophy of the cerebral hemispheres. The patches of bright signal intensity in the bilateral thalami (open arrows) suggest a subacute stage of hemorrhage. The localized bright signal intensity in the periventricular white matter and in the right thalamus on T2 weighted images (D) suggest the cystic evolution.

Fig. 2

MRIs of a 5-month-old boy (patient 5) who recovered completely. A, B. The initial T2-weighted images reveal the bilateral thalamic swelling. The posterior limb of the internal (arrowheads) capsule, external capsule (arrows), and the pons (arrow, B) are also involved. C, D. Follow-up images obtained 18 days later show the thalamic swelling has subsided and disappeared as compared to the abnormal signal intensity noted on prior MR images. E. Generalized cerebrospinal fluid space widening is seen 6 months after the initial MR scan.