Treatment of paresis

Abstract

The vast majority of current ideas and practices for the treatment of cerebral paresis are rooted in stroke research. Consequently, the consensus is that 95% of patients reach their optimum overall neurological function by 3 months from an incident. It is also believed that motor recovery reaches a plateau 3-6 months after the incident, and additional gains with current standard therapies are relatively minor. This mindset has now been greatly challenged by emerging neuromodulatory approaches, in particular by repetitive (rTMS). Three potential roles have been described for rTMS in rehabilitation: (1) inhibiting, i.e., downregulating, the nonlesioned side (low frequency, 1 Hz rTMS), (2) exciting the lesioned side (high frequency, =10 Hz rTMS), and (3) combining both approaches to reach the optimal excitation-inhibition balance in motor systems for relearning lost motor skills. All neuromodulatory approaches without exception require integrated occupational therapy or physiotherapy for motor relearning; as such, no current standardized therapy protocol shows proven superiority with respect to the others. Despite the enthusiasm for neuromodulatory approaches and several promising early results, rTMS neuromodulation is still in its translational stage of moving from research to clinical practice. Brain lesions leading to paresis can be extremely variable by location, size, and the amount of completely destroyed vs. damaged but still viable tissue in the vicinity of the lesion. Motor lesions can also cause symptoms and signs from remote parts of the interconnected motor network, leading to diaschisis. Most importantly, the majority of studies utilizing transcranial neuromodulatory approaches face methodological uncertainties; the exact location of stimulus delivery is often not known, the intensity or "dose" of stimulus is not uniform across the subjects, the patient sample sizes are small, and combining the study results is impossible because of methodological differences-there are simply too many unknowns. These problems could potentially be solved by utilizing navigated rTMS (nrTMS) to minimize the inaccuracies of stimulus delivery, by conducting multicenter projects concentrated on stratified patient groups, and by securing a priori agreements on test protocols to gain large enough comparable datasets. The ultimate goal for adjuvant therapies such as nrTMS is to provide a more receptive neuronal environment through which behavioral therapies may be imparted.