Diffusion-weighted MRI for early diagnosis of neonatal herpes simplex encephalitis

To determine the early changes and evolutions of brain diffusion-weighted imaging (DWI), and analyze prognostic factors of the early changes among patients with neonatal herpes simplex encephalitis (NHSE).

We selected patients who developed encephalitis by 28 d after birth; had herpes simplex infection; and who underwent magnetic resonance imaging, including DWI, ⩽7 d of symptom onset. Thirty-two DWI scans between 0 and 28 d after onset in 13 patients and the clinical data were recruited. The distribution, evolution of the lesions, and neurological outcome were analyzed.

DWI frequently showed multiple cortical lesions in both hemispheres in the early period and both hemispheres on DWI (8/9 scans at ⩽48 h, 7/7 patients). As time from onset increased, the cortical lesions tended to coincide with subcortical white matter lesions beneath the initial cortical lesions (p<0.01). Lesions from the cortex extended to the subcortical white matter in 7 patients. Deep cerebral lesions, involving basal ganglia, internal capsules, thalamus, were also found in 9 patients ⩽7 d of onset. The distributions of deep cerebral lesions (none/unilateral/bilateral) ⩽7 d of onset showed significant correlations with neurological prognoses (gross motor functions: p<0.01; developmental or intellectual quotient scores: p<0.01).

Cortical lesions were main findings of DWI in NHSE in the early period. Bilateral deep cerebral lesions ⩽7 d were highly indicative of poor motor and cognitive outcomes.