Aurora Semerano, MD

European Stroke Organisation-World Stroke Organization 2020 Virtual Conference
November 7-9, 2020

The Controversies sessions during the ESO-WSO 2020 Conference are intriguing live Q&A sessions focused on grey zones in stroke care, with stroke experts defending their points of view and facing each other in interesting rounds of discussion. On the second day of the conference, the session addressed the following topics about recovery and brain repair after stroke.

Round 1:

Brain Repair is the Right Target to Improve Outcome — John Krakauer (United States of America)
Basing on primate experimental stroke, Dr. Krakauer showed that a certain rate of spontaneous recovery exists after stroke; however, training helps to amplify, rescue, and maintain spontaneous recovery. The main question remains: How does it happen? According to Dr. Krakauer, training-induced recovery in monkeys is not driven by cortical reorganization. Conversely, brain repair occurs via training-induced strengthening of pre-existing alternative cortico-subcortical connections. The recipe for brain repair after stroke is traced: an integrated interaction between behavior, residual architecture, and plasticity.

Brain Repair Does Not Work, Reorganisation is Key — Belen R. Ballester (Spain)
Dr. Ballester dismantled in 15 minutes three common pessimistic beliefs about recovery after stroke. Behavior drives functional and structural reorganization and can meaningfully interact with spontaneous recovery. For this purpose, high repetitive task-oriented and task-specific training is needed. Possibilities for recovery extend well beyond the classical time window of 3-6 month, and plasticity by means of structural and connectivity changes is still present beyond 1 year after stroke. Finally, it is not an invariable destiny of stroke patients to deteriorate in the chronic phase; learning and training can prevent deterioration.

Round 2:

The More the Better — More Therapy Can Improve Recovery — Nick Ward (United Kingdom)
Dr. Ward discussed existing clinical trials by dose of intervention, illustrating that increasing time of therapy results in recovery improvement. It is calculated that the required amount of practice should be more than tripled from what is usually provided. However, therapy dose may act differently on the three domains of recovery (that is to say, improvement in body structures and function, activity and participation). He also illustrated his experience from the Queen Square Upper Limb Neurorehabilitation programme, a complex intervention delivering high-dose and high-intensity upper limb neurorehabilitation during a 3-week (90 hours) programme. The next step will be to define and differentiate treatments by the pattern of effects they have on a range of outcome measures, in order to better understand how we can combine them effectively.

It’s Just Spontaneous Recovery — Therapy Only Drives Behavioral Compensation — Gert Kwakkel (Netherlands)
Dr. Kwakkel’s talk focused on the impact of time on recovery. He calculated the impact of the progress of time, adjusted for covariates, on the biweekly observed improvement early after stroke: The time course of recovery is non-linear and plateaus within the first ten weeks, and, importantly, time alone explains about 90% of the variance of neurological and functional recovery within the first weeks after stroke. So, what is the impact of therapy? If intense and task-specific, therapy may be effective in determining the 5-10% of the variance in improvement of activities, however, this is mainly due to compensation strategies. Patients apply these strategies in order to be able to cope with the underlying neurological deficits.

Round 3:

Non-Invasive Brain Stimulation is Getting Close to Clinical Application for Stroke — Alexander Thiel (Canada)
According to Dr. Thiel, non-invasive brain stimulation is getting close to clinical application, at least for some patients. To get the most from these techniques, it is fundamental to identify the patients which may benefit from non-invasive brain stimulation, the right time for the treatment, and the right paradigm to use. Going to the existing evidence about inhibitory stimulation of contralateral hemisphere by rTMS, data suggest that we are on the right track. Treating patients with hemiparesis in the subacute phase, as well as the patients with aphasia in the subacute or chronic phase, yields better outcome than treating patients with rehabilitation only. The next step will be to generate class I evidence in large multicentric clinical trials.

Non-Invasive Brain Stimulation for Stroke Recovery Has Failed — Meret Branscheidt (Switzerland)
Dr. Branscheidt started with a quotation by Thomas Edison to describe the state of the art with non-invasive brain stimulation after stroke: “We haven’t failed. We have just found 10000 ways that won’t work.” She moved to resume data from comprehensive meta-analyses on tDCS and rTMS for stroke recovery, showing that little evidence exists for supporting the routine use of these techniques. What might be the problem? She identified different categories of factors that we should address in the future: conceptual factors about the rationale, technical problems, and pitfalls in the study design of the previous trials. In conclusion, we need to state our rationale very clearly, to systematically optimize technical factors, and to design our trial stressing the importance of acute/subacute interventions and long-term observation.