Defining abnormal slow EEG activity in acute ischaemic stroke: Delta/alpha ratio as an optimal QEEG index.
OBJECTIVE To explore the relationship between three QEEG global indexes and their association with functional outcome after neurorehabilitation in non-acute acquired brain injury (ABI) patients (traumatic brain injury and stroke). METHODS Twenty-one adult ABI patients in post-acute phase were studied. Delta-alpha ratio (DAR), Power Ratio Index (PRI) and Mean Brain Symmetry Index (mBSI) were calculated from resting-state EEG taken at admission. These indexes and other clinical variables were correlated with functional recovery achieved after six months of neurorehabilitation. RESULTS DAR showed the highest strength of association with the functional outcome measure (rho=-0.65, P=0.002). The other QEEG indexes and clinical variables showed modest non-significant correlations. A posteriori group analysis showed higher DAR in patients with poor recovery as compared to good recovery patients. CONCLUSIONS Functional recovery after neurorehabilitation appears to be associated with a number of clinical and neurophysiological variables. Among the latter, the ratio between delta and alpha may play a significant role in predicting and monitoring functional rehabilitation outcome. SIGNIFICANCE Neurophysiological assessment of ABI patients may be an important tool in monitoring and predicting outcomes after neurorehabilitation.