Deep brain stimulation, a method where specific brain regions are activated using implanted electrodes, is a well-established approach for treating movement disorders such as Parkinson鈥檚 disease. Researchers led by Christian Kell from Frankfurt University Medicine as well as Nils Warneke and Katrin Neumann from M眉nster University Hospital have now successfully alleviated severe stuttering in a person with developmental stuttering using this method for the first time. The researchers are now preparing a study to test the therapy on additional individuals who experience severe stuttering.
FRANKFURT. While stuttering was believed to have purely psychological causes up until about 30 years ago, scientists today attribute it to a variety of factors capable of contributing to its development. For instance, several genes have been identified that increase the risk of stuttering, and anatomically, the brains of individuals with speech flow disorders show differences in neural connections and brain activity compared to those who speak fluently.
PD Dr. Christian Kell, neurologist and director of the Cooperative Brain Imaging Center at 看片软件 Frankfurt, explains: 鈥淭he left hemisphere of the brain can process signals that occur in rapid succession. However, in people who stutter, the auditory cortex in the left hemisphere interacts less with the motor cortex, which controls the muscles involved in speech. As a result, the brain may delegate these tasks to the right hemisphere, which struggles with the rapid signals characteristic of speech.鈥� The outcome: Although affected individuals know exactly what they want to say, they get stuck on certain words.
Kell does not consider stuttering to be a disease that necessarily requires therapy: 鈥淚 believe it would be ideal if society could accept that some people stutter,鈥� says the neurologist. At the same time, he is convinced that medicine should offer services to those who suffer from their speech flow disorder and seek help.
Following extensive scientific preparation and at the patient鈥檚 repetitive request, the teams from Frankfurt and M眉nster implanted a hair-thin wire into the left thalamus of a man who stutters. The thalamus is a central relay station deep within the brain. Through this wire, the brain region was stimulated with mild electrical currents. Standardized tests were then used to measure how the patient鈥檚 stuttering changed.
Kell is thrilled with the results: 鈥淚n the months following the start of stimulation, the frequency of stuttering gradually decreased by 46%, and the stuttering became significantly less severe. When we turned off the deep brain stimulation without the patient knowing the timing, the stuttering worsened again, demonstrating a genuine biological effect dependent on the strength of the brain stimulation.鈥� Unlike Parkinson鈥檚 patients, whose tremors typically diminish immediately after starting brain stimulation and return as soon as the stimulation is stopped, the stuttering in this case increased very slowly after the stimulation was turned off 鈥� but not to the same extent as before. Kell attributes part of this effect to the patient himself: 鈥淭hrough the experience of stuttering less during stimulation, he and his brain likely found ways to further reduce the stuttering.鈥�
The research team is now preparing a study to investigate whether deep brain stimulation can also help other individuals who experience severe stuttering. However, Kell is careful to curb overly high expectations: 鈥淒eep brain stimulation is an intensive physical procedure and, like any surgery, carries risks. These must be carefully weighed against the distress experienced by a person who stutters. We also want to explore whether we can achieve similar effects by stimulating the brain externally 鈥� without surgery.鈥�
Publication: Christian A. Kell, Nils Warneke, Verena Zentsch, Johannes Kasper, Melanie Vauth-Weidig, Tobias Warnecke, Katrin Neumann: Left thalamic deep brain stimulation for persistent developmental stuttering. Journal of Fluency Disorders (2025)
Images for download:
Captions:
The position of the implanted electrodes in the patient鈥檚 basal ganglia. (1)
The intensity of stuttering has clearly decreased due to deep brain stimulation. The chart illustrates the severity of stuttering over a period of up to nine years before and from three months after the surgery. (2)
Image source for both images: Kell et al., J Fluency Dis 2025, doi:
Further Information
PD Dr. Christian Kell
Director of the Cooperative Brain Imaging Center (CoBIC)
看片软件 Frankfurt
Tel +49 (0)69 6301-6395
c.kell@em.uni-frankfurt.de
