Acute necrotizing encephalopathy of childhood: correlation of MR findings and clinical outcome

Abstract

Background and purpose: The clinical outcome of acute necrotizing encephalopathy of childhood (ANEC), an encephalopathy characterized by symmetrical involvement of the thalami, has historically been poor, but recent studies have reported better outcomes. By devising a MR imaging scoring system, we determined the relationship between characteristic MR findings and clinical outcome of patients with ANEC.

Methods: MR studies of 12 patients with ANEC were retrospectively reviewed. A MR imaging score was calculated for each patient according to the presence of hemorrhage, cavitation, and location of lesions. Clinical outcome of the patients was assessed, yielding outcome categories based on health state utility value. Spearman rank test was used to correlate the MR imaging score with clinical outcome of the patients.

Results: Statistically significant correlation (r = 0.76, P = .001) was found between the MR score and the outcome category. The thalami were involved in all 12 patients, brain stem in 10, cerebral white matter in 8, and cerebellar white matter in 4. Hemorrhage was present in 5 patients and cavitation in 4. Clinical outcome category was 1 in 2 patients, 2 in 8 patients, and 3 in 2 patients. No patients were in category 4.

Conclusion: There is a significant and positive correlation between the clinical outcome and the MR imaging score in patients with ANEC. The relation between clinical outcome and each individual MR feature remains to be determined. Patients with ANEC may have a better clinical outcome than has been previously reported.

Fig 1.

A 1.3-year-old boy (patient 1) left with spasticity and decerebrate posture. A, coronal T2-weighted imaging (4000 ms/90 ms, repetition time [TR]/echo time [TE]) shows symmetrical hyperintensity in the thalami (arrows), the centrum semiovale (arrowheads), and the brain stem, including the midbrain (double arrowheads) and the pons (double arrows). Note swelling of the thalami. B, Postcontrast coronal T1-weighted imaging (630 ms/20 ms, TR/TE) shows irregular ringlike enhancement in the thalami (arrows).

Fig 2.

A 2.3-year-old boy (patient 12) with severe sequelae. A, Axial T1-weighted imaging (449 ms/12 ms, TR/TE) shows sharply marginated hypointensity in the cerebellum (arrowheads). B, Axial T1-weighted imaging shows hyperintensity in the thalami (arrows) and the right occipital lobe (double arrows). Sharply marginated hypointense areas are found in the cerebral white matter (arrowheads) and the internal capsules (small arrowheads). The lentiform nuclei also show mixed intensity (double arrowheads). C and D, Coronal T2-weighted imaging show mixed intensity in the thalami (arrows), and hyperintensity in the cerebral white matter, internal capsules (small arrowheads), and the cerebellum (double arrowheads). There are 2 types of white matter lesions: those in the central white matter and internal capsules showing hyperintensity comparable with the CSF (arrowheads) and those in the subcortical regions being less hyperintense (double arrows).

Fig 3.

A 10-year-old boy (patient 5) recovered with hand tremor. Follow-up coronal T2-weighted imaging shows shrunken bilateral thalami with cavitation (arrows).