Neurophysiological tests in children brain injured: when, how?

Abstract

Neurophysiological tests complete clinical and radiological assessments in brain-injured children. Electroencephalogram (EEG) is clearly helpful to diagnose seizures and brain death while auditory evoked potentials (EP) to assess brainstem dysfunction and predict poor neurological outcome in post-anoxic coma. During the acute phase of severe traumatic brain injury (TBI) and bacterial meningitis, early recognition and treatment of convulsive seizures is essential. The incidence of non-convulsive seizures remains, however, high, varying between 7 and 48%. Although costly and time consuming, continuous EEG monitoring techniques may allow improving seizure detection. Therefore, amplitude integrated EEG techniques have been developed; however, they still require assessment in paediatrics. Some EEG patterns are indicative of a final bad outcome, including burst suppression, isoelectric pattern, and status epilepticus. EEG predictive value remains limited and less useful than somatosensory EP (SEP). SEP have excellent predictive value in post-anoxic coma in adults as well as in children (94 to 100%), especially in combination to pupillary reflexes and motor responses assessed after 48 h. In contrast, their predictive value of a good outcome is less reliable. In severe TBI and bacterial meningitis, this performance is also limited. Investigation of cognitive EP or mismatch negativity (MMN) could improve awakening prediction.