Prognostic value of evoked potentials and sleep recordings in the prolonged comatose state of children. Preliminary data

Objectives - Sleep recordings and evoked potentials (EPs) were, used in fiv e comatose children to evaluate their predictive value for outcome followin g a severe comatose state. Methods and subjects - The protocol included EEG , Brainstem Evoked Responses (BERs), Somatosensory Evoked Potentials (SEPs) and polysomnography. From 10 to 15 days post-coma (D10 to D15), EEG and cl inical examinations were carried out every second day, then one day in four from 15 to 30 days post-coma (D15 to D30), and one day in seven from D30 t o six months (M6). Evoked potentials and Polysomnography were recorded on D 10-D15 or D30 in the second month (M2) and in M6. Of the five children, thr ee were in anoxic coma and two in traumatic coma. All had extensive lesions and a Glasgow Coma Scale (GCS) score of less than five. The results of the EEG, polysomnographic and EP recordings were compared to the clinical outc ome. Results and conclusion - In the three anoxic comas we observed BER abn ormalities and the absence of SEP N20 associated with wide cortical lesions with brainstem extension. Sleep recordings showed major alterations of the wake-sleep cycle without any improvement in M6, Abnormalities included los s of the normal REM-sleep pattern associated with alteration of NREM sleep and periods of increase in motor activity without EEG arousal. This sleep p attern appeared to be associated with involvement of the brainstem. in the two traumatic comas, alterations of the early cortical SEP responses were l ess severe and the BERs were normal. Some sleep spindles were observed as w ell as the persistence of sleep cycles in the first weeks post-coma. The co mbined use of EEG, EPs and polysomnography improved the outcome prediction in comparison with the use of just one modality. EPs and sleep recordings w ere far superior to clinical evaluation and to GCS in the appreciation of t he functional status of comatose children. The reappearence of sleep patter ns is considered to be of favorable prognosis for outcome of the coma state , as is the presence of sleep spindles in post-trauma coma. This study show ed that EPs and sleep recordings help to further distinguish between patien ts with good or bad outcomes. (C) 2001 Editions scientifiques et medicales Elsevier SAS.