Somatosensory Evoked Potentials as a Predictor for Functional Recovery of the Upper Limb in Patients with Stroke

Background: Predicting motor recovery in the arm of patients with stroke is generally based on clinical examination. However, neurophysiologic measures may also have a predictive value. Objective: We sought to assess the value of somatosensory evoked potentials (SSEPs) in predicting motor recovery of the upper limb and to determine whether any of the SSEPs components can predict the severity of the deficit so that it can document the size of the stroke (lacunar or large-vessel stroke). Method: In all, 22 patients who had had a first-ever stroke and presented with obvious motor deficit of the arm were examined in terms of 3 clinical variables (motor performance, muscle tone, and overall disability) and for SSEPs. Clinical (Medical Research Council [MRC] scale and Barthel index scores) and neurophysiologic examinations were done at entry to the study (first week poststroke) and 3 months after stroke. Results: Significantly low mean MRC scale score was found at first week versus after 3 months of stroke and in patients with large-vessel as compared with lacunar stroke both at first week and after 3 months. The mean Barthel index score was significantly higher after 3 months than at first week, whereas it was significantly lower in large-vessel as compared with lacunar stroke both at first week and after 3 months of stroke. Significantly prolonged N-20 latency, low peak-to-peak amplitude (PPA), and low amplitude ratio were found in patients with stroke as compared with control subjects. None of the neurophysiologic parameters were different in the patients with stroke between first week and third month. The MRC score and PPA were correlated well with the Outcome MRC and Barthel index scores after 3 months. N-20 latency correlates with the outcome MRC score but not with the outcome Barthel index score. Interestingly, the N-20 latency was significantly different in lacunar from large-vessel stroke. Conclusion: The muscle power (MRC score) is the main outcome predictor in patients with stroke. PPA is the main SSEPs component with high prognostic value in stroke. The SSEPs N-20 latency can predict (even roughly) the size of cerebral infarction (whether lacunar or large-vessel stroke).