Motor evoked potentials in predicting motor and functional outcome after stroke

Abstract

The use of motor evoked potentials (MEPs) in predicting motor and functional outcome represents the central issue of this thesis. The thesis is divided into 3 parts. Two pilot studies are described in part I. Part II consists of 2 systematic reviews, and the prospective cohort studies are described in part III. Both pilot studies indicated that evoked potentials predict the occurrence of motor recovery of upper extremity paralysis in acute stroke patients. The first systematic review focuses at motor recovery after stroke. The purpose of the study was to collect and integrate existing data concerning the occurrence, extent, time course and prognostic determinants of motor recovery after stroke. The initial grade of paresis is the most important predictor for motor recovery (ORs, > 4). Objective analysis of the motor pathways by motor evoked potentials (MEPs) showed even much higher ORs (ORs, >20). We concluded that our knowledge of motor recovery after stroke in more accurate, quantitative and qualitative terms is still limited and a precise prediction of motor recovery in an individual acute stroke patient is not possible. MEPs seem to be promising within this context. In the second systematic review we addressed specifically the use of MEPs in predicting motor and functional outcomes. We concluded that evidence exists for the prognostic value of MEPs with respect to motor and functional recovery. The specificity was consistently very high for subgroups of patients with paralysis or severe paresis, and this test property might be used in clinical practice. The predictive value of MEPs with respect motor recovery of the upper and lower extremity, and functional recovery, was obvious in the 3 prospective cohort studies (last part of the thesis), which agrees with the paradigm that postinfarctional motor recovery is strongly dependent on a critical residual sparing of corticospinal function