Can TMS of forearm muscles improve prediction of dexterity after stroke?

In the acute phase after stroke, active finger extension is a strong predictor of long-term dexterity. Transcranial magnetic stimulation (TMS) with surface electromyography of proximal arm and intrinsic hand muscles has proven to be of additional prognostic value to clinical assessment, especially in patients unable to follow instructions. The current study aimed to determine whether TMS of the extensor digitorum communis (EDC) further improves the prognostic accuracy. Motor evoked potentials (MEPs) of the EDC at rest and Fugl-Meyer Assessment (FMA) of the upper extremity were measured in 18 participants within 4 weeks after stroke, and included as independent variables in a multiple linear regression analysis with the FMA at 26 weeks after stroke as dependent variable. The data demonstrated that the EDC resting MEPs had no additional value over clinical predictors, but a large MEP amplitude increased the likelihood of a high FMA score at 26 weeks. An absent EDC resting MEP did not preclude return of dexterity.