Speech disorders after a stroke: Networks in the brain help each other to compensate for damage

After a stroke, many sufferers suffer from speech disorders. In the brain, functions such as language are located in networks. After a stroke, these networks are disrupted. In a recent study, neurologists from the University Hospital Leipzig (UKL) headed by Prof. Dorothee Saur investigated how the human brain compensates for this damage. The work was published in the March issue of the journal "BRAIN", one of the world's most important journals for neurology.

The results of the study from the working group led by Prof. Saur, Senior Physician at the Clinic and Polyclinic for Neurology of the UKL, and Dr. Anika Stockert as first author opens up a new understanding of language recovery after a stroke.
"We were particularly interested in how the disrupted network reorganized itself to compensate for the disruption," describes Prof. Saur. At the UKL's special stroke ward, patients with aphasia, i.e. a speech disorder, were examined with a so-called functional MRI in the first few days after a stroke: "This means that the patients receive simple sentences from us to listen to during the MRI examination . In this way, we can see which brain regions are actively communicating with each other while the patients hear these sentences," explains the neurologist.
Not only the structure, but also the functions of the brain can be represented in this way. If this happens at an early stage, the doctors can not only recognize the disruptions in the networks, but also their changes. "After two weeks and after half a year we repeat the whole thing and then see the development and recovery," says Prof. Saur.
The effort for the study was considerable. 34 selected cases were included in the final evaluation, each patient had to be examined three times in the specified periods.

What was particularly interesting was what could be observed in the course of time after the stroke: “In the acute state, we recognize significant network disturbances, depending on where in the brain the infarction took place. As a result, networks that were not destroyed by the infarction are mobilized,” she explains. "Even those who aren't even responsible for language help with recovery." Brain tissue close to the infarction only recovers later, after a few months. "This understanding is crucial," says Prof. Saur, "because only if we know the brain regions that are important for recovery can we specifically stimulate them and thus promote healing."

Following this idea, the UKL neurologists are now developing in cooperation with private lecturer Dr. Gesa Hartwigsen and joint doctoral student Sandra Martin from the neighboring Max Planck Institute (MPI) for Human Cognitive and Brain Sciences conducted a study in which the networks critical for speech recovery in stroke patients with chronic aphasia are stimulated with magnetic stimulation. "We see great potential for neurorehabilitation in the use of such individualized network therapies in addition to speech therapy," says Prof. Saur optimistically.

Source: Leipzig University Hospital press release from October 23.03.2020, XNUMX