Multimodal neuroelectrophysiological studies to predict outcome in paediatric patients with traumatic brain injury

Introduction

A prognostic tool is needed in the early assessment of paediatric patients with traumatic brain injury (TBI). The combination of electroencephalography and evoked potentials may help predict outcome.

Methods

We enrolled patients with TBI admitted to the Paediatric Critical Care Unit with an initial GCS of 12 or less. Patients had an electroencephalogram (EEG), visual evoked potentials (VEPs) and somatosensory evoked potentials (SEPs) done within 60 hours of admission to the PICU, and repeated within 7 days. A CT scan was done on admission. EEG, VEP and SEP were scored. The EEG was analyzed for synchrony using the Hilbert transform. Outcome was measured at 3 months using the Paediatric Cerebral Performance Category Score (PCPC).

Results

Seven patients aged 3–13 were enrolled. Lowest recorded GSC ranged from 5 to 12. Three of the seven patients developed intracranial hemorrhage. Four of the seven patients sustained diffuse axonal injury; these patients had encephalopathic EEG patterns. Children whose EEG had normal background activity had better outcomes at 3 months. Those who regained normal background activity on the second EEG had intermediate outcomes. Children having the worst scores for EEG and SEP had worst functional outcome. EEG score did not show a correlation with change in the PCPC. Encephalopathic EEGs showed increased synchrony compared with EEGs having a normal background (Fig. 1). Increased SEP latency in cortical to cortical relays correlated with poor functional outcome. SEP score did correlate with change in the PCPC (Pearson coefficient r = 0.82, P = 0.02). Children whose EEG showed attenuated occipital background patterns had large-amplitude VEPs. Current scoring systems for VEPs do not account for this observed increase.

Figure 1

Synchrony pattern from EEG electrode C3 of patient 2 in the delta frequency range. Red, maximal synchrony; blue, minimal synchrony. Patient demonstrates synchrony between C3 and between electrodes 1–3, 8–11 and 18. Synchrony is pathological.

Conclusions

Our results indicate that SEP correlates directly with outcome. EEG synchrony correlates with outcome. High-amplitude VEPs may reflect neuronal hyperexcitability The significance of this needs further investigation.