The National Spasmodic Dysphonia Association is strongly committed to understanding the science of SD and supporting research. Grants currently being funded by the NSDA include:
Parametric Analyses of Pathology and Treatment Effect in SD
Christian Kell, M.D.
Goethe University, Frankfurt, Germany
This proposed research will be conducted by a neurologist, Dr. Christian Kell, and is entitled, “Parametric analyses of pathology and treatment effect in spasmodic dysphonia”. This study will involve both structural and functional brain imaging in persons with spasmodic dysphonia before and after treatment with botulinum toxin injection. The purpose of this brain imaging research is to determine what parts of the brain are altered both structurally and functionally and may account for voice abnormalities in persons with spasmodic dysphonia. Because treatment with botulinum toxin is only effective for a short period and the symptoms reappear after the effects of the toxin wear off, the authors plan to identify brain regions that are abnormal in persons with spasmodic dysphonia regardless of symptoms or treatment with botulinum toxin. It is hoped that by finding both structural and functional abnormalities in the brain that are present regardless of treatment by botulinum toxin that the authors will identify the brain abnormality responsible for producing symptoms such as voice breaks in spasmodic dysphonia. Once this region is known, then future research can be aimed at changing this brain abnormality for long term treatment in SD.
In previous research, two studies found that functional differences occurred in brain activity in persons with spasmodic dysphonia (SD). One was a study conducted at the National Institute of Health by Ali et al., and published in the Journal of Speech-Language Hearing Research in 2006. The authors used Positron Emission Tomography (or PET) to measure activity in the brain and found that when persons with SD either whispered or did not have voice symptoms they had reduced brain activity in the region that receives sensory feedback from the larynx. Once the patients were treated with botulinum toxin injections this abnormality disappeared suggesting it might have been the result of symptoms rather than causing the symptoms. However, another brain abnormality was present in persons with SD both when they had symptoms and when they did not—reduced activity in the supplementary motor area (SMA). This area was identified as being involved in speech production many years ago by Dr. Wilder Penfield and colleagues in the 1940s and 1950s. Abnormalities in the SMA were present in the persons with SD even when they whispered, suggesting that this abnormality was always there. Another study by Haslinger et al., 2005 was conducted in Munich, Germany and published in the journal Neurology. These authors found reduced brain activation in the primary sensorimotor areas which was not altered by treatment. Only one study thus far has examined structural differences in the brains of persons with SD; this was conducted at the National Institutes of Health by Simonyan et al., and published in the journal Brain. These authors used high resolution structural imaging with a special technique, diffusion tensor imaging, and found reductions in the white matter tracts on the right side of the brain which were confirmed in a one post-mortem study of a brain from an SD patient.
The research to be supported by the NSDA and conducted by Kell et al., in Frankfurt Germany will be the first combined use of both functional and structural techniques in the study of the brain in persons with SD using high resolution imaging. This will involve a collaboration across two centers between Dr. Kell, a neurologist and Dr. Katrin Neuman, an otolaryngologist both at Goethe University in Frankfurt and Dr. de Jonckere, a speech language pathologist at the University of Utrecht in The Netherlands. Two years of support will be provided and this study should build on research that has already been done but provides a unique opportunity to learn which of the brain functional and structural abnormalities found by other scientists are always present in SD and should be focused on to develop long-lasting treatments for persons with SD.