Guidelines for the management of encephalitis in children

Indications for the performance of neuroimaging in children

Pediatric neurology relies on ultrasound, computed tomography (CT), and magnetic resonance (MR) imaging. CT prevails in acute neurologic presentations, including traumatic brain injury (TBI), nontraumatic coma, stroke, and status epilepticus, because of easy availability, with images of diagnostic quality, e.g., to exclude hemorrhage, usually completed quickly enough to avoid sedation. Concerns over the risks of ionizing radiation mean re-imaging and higher-dose procedures, e.g., arteriography and venography, require justification. T1/T2-weighted imaging (T1/T2-WI) MR with additional sequences (arteriography, venography, T2*, spectroscopy, diffusion tensor, perfusion, diffusion- (DWI) and susceptibility-weighted imaging (SWI)) often clarifies the diagnosis, which may alter management in acute settings, as well as chronic conditions, e.g., epilepsy. Clinical acumen remains essential to avoid imaging, e.g., in genetic epilepsies or migrainous headaches responding to treatment, or to target sequences to specific diagnosis, e.g., T1/T2-WI for shunt dysfunction (with SWI for TBI); DWI, arteriography including neck vessels, and venography for acute hemiplegia or coma; coronal temporal cuts for partial epilepsy; or muscle imaging for motor delay. The risk of general anesthesia is low; "head-only" scanners may allow rapid MRI without sedation. Timely and accurate reporting, with discrepancy discussion between expert neuroradiologists, is important for management of the child and the family's expectations.

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

AIM

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).

METHOD

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.

RESULTS

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).

INTERPRETATION

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.