The aim of our working group is to understand better the pathophysiology of speech fluency disorders, especially stuttering that develops in childhood.

To succeed in this endeavour, we use neuro-radiological (structural and functional MRI) and neurophysiological methods, in particular transcranial magnetic stimulation and electroencephalography, depending on the research question.

Stuttering is a widely recognised speech fluency disorder of unexplained cause. It is characterized by involuntary repetitions and prolongations of sounds and syllables, and speech blocks.¹ Verbal or situational avoidance behaviour and involuntary movements may develop over time.²

Approximately 7 million people in Europe stutter. Stuttering affects at least 5% of all children and has an astonishing rate of early recovery. After puberty, recoveries are extremely rare and about 1% of all adults stutter.^{3, 4} Stuttering that persists into adulthood can lead to significant restrictions in quality of life and social and professional development.⁵

For centuries,⁶ it was not clear why stuttering develops, nor why it disappears more or less spontaneously in many affected children. In the last 20 years, our group has contributed to generating evidence from neuroscience that stuttering is associated with both morphological and functional changes in the brain.⁷ Neuroscientific studies have provided insights into the brain structure and pathophysiology of stuttering, and its interaction with speech therapy.^{8, 9} New real-time MRI technologies allow a better understanding of aberrant movements during stuttering events. Ultrasound examination of the midbrain allows quantification of iron deposits in the substantia nigra.¹⁰ Testing whether this has any prognostic value is an endeavour currently getting underway. External neurostimulation reveals disturbed interactions of inhibitory and facilitatory control circuits in the motor cortex of adults who stutter.¹¹

In recent years, large epidemiological data sets show atopic diseases as previously unrecognised comorbidities.¹² Coping strategies and social anxiety receive more attention and may be independent treatment goals.¹³

The aim of our working group is to uncover further neurobiological processes of stuttering and its development. From the perspective of neurological movement disorders, we are interested in the temporary loss of motor control in stuttering, and how this changes through therapy or spontaneously. We investigate neurological correlates and causes of this loss of control using neurophysiological and imaging methods.

1.         American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 5th edition ed. Washington, D.C.: American Psychiatric Association, 2013.

2.         Mulligan HF, Anderson TJ, Jones RD, Williams MJ, Donaldson IM. Dysfluency and involuntary movements: a new look at developmental stuttering. Int J Neurosci 2001;109(1-2):23-46.

3.         Yairi E, Ambrose NG. Early childhood stuttering I: persistency and recovery rates. J Speech Lang Hear Res 1999;42(5):1097-1112.

4.         Sommer M, Waltersbacher A, Schlotmann A, Schröder H, Strzelczyk A. Prevalence and Therapy Rates for Stuttering, Cluttering, and Developmental Disorders of Speech and Language: Evaluation of German Health Insurance Data. Front Hum Neurosci 2021;15:645292.

5.         McAllister J, Collier J, Shepstone L. The impact of adolescent stuttering on educational and employment outcomes: evidence from a birth cohort study. J Fluency Disord 2012;37(2):106-121.

6.         Leon-Sarmiento FE, Paez E, Hallett M. Nature and nurture in stuttering: a systematic review on the case of Moses. Neurol Sci 2012;2012.

7.         Sommer M, Koch MA, Paulus W, Weiller C, Buchel C. Disconnection of speech-relevant brain areas in persistent developmental stuttering. Lancet 2002;360(9330):380-383.

8.         Korzeczek A, Primaßin A, Wolff von Gudenberg A, et al. Fluency shaping increases integration of the command-to-execution and the auditory-to-motor pathways in persistent developmental stuttering. Neuroimage 2021;245:118736.

9.         Neef NE, Korzeczek A, Primaßin A, et al. White matter tract strength correlates with therapy outcome in persistent developmental stuttering. Hum Brain Mapp 2022;43(11):3357-3374.

10.       Liman J, Wolff von Gudenberg A, Baehr M, Paulus W, Neef NE, Sommer M. Enlarged Area of Mesencephalic Iron Deposits in Adults Who Stutter. Front Hum Neurosci 2021;15:639269.

11.       Elfers A, Hommel S, Neef N, Wolff von Gudenberg A, Paulus W, Sommer M. 1207 Motor intracortical excitability before speech onset in adults who stutter. Movement Disorders 2019;34(Suppl. S2):S500.

12.       Ajdacic-Gross V, Rodgers S, Müller M, et al. Hay Fever is Associated with Prevalence, Age of Onset and Persistence of Stuttering. Advances in Neurodevelopmental Disorders 2020;4:67–73.

13.       Menzies RG, Packman A, Onslow M, O'Brian S, Jones M, Helgadóttir FD. In-Clinic and Standalone Internet Cognitive Behavior Therapy Treatment for Social Anxiety in Stuttering: A Randomized Trial of iGlebe. J Speech Lang Hear Res 2019;62(6):1614-1624.

If you stutter and would like to participate in our research for a better understanding of stuttering, write an email to Prof. Sommer msommer(at)gwdg.de

People who stutter with questions about therapy and therapy satisfaction please contact the independent counselling centre of the Bundesvereinigung Stottern & Selbsthilfe e.V., Zülpicher Straße 58, 50674 Köln, phone: 0221 139-1106, fax: 0221 139-1370, email: info(at)bvss.de This association maintains a very informative website (www.bvss.de) with a variety of information about stuttering. This association is not a public institution, but an association supported by people who stutter and other committed people. It depends on your support and can make good use of donations.