July 5, 2019

Deep Brain Stimulation and Dystonia: The Vercise™ Dystonia Registry

Interview with Prof. Joachim Krauss, Director of the Department of Neurosurgery at the
Medizinische Hochschule Hannover, Germany

Prof. Krauss, a pioneer in surgical dystonia treatment, has been involved in deep brain stimulation (DBS) therapy since its development in the early 1990s. Under his stewardship as the Director of the Department of Neurosurgery at the Medizinische Hochschule Hannover (MHH) in Germany for the past 15 years, the centre has become one of the leading DBS centres for dystonia-treatment and research in the world. Together with Prof. Alberto Albanese (Instituto Clinico Humanitas, Rozzano, Italy) he is currently the coordinating investigator for an ongoing registry to better understand the treatment of dystonia with DBS. We caught up with him to learn more about this registry.

What is your background in dystonia and DBS?
Actually, my interest to help people that are suffering from dystonia was triggered during my residency in the 1980s, many years before I started performing DBS. I got involved in deep brain stimulation in 1995 in Houston, Texas, where Rick Simpson and I introduced the therapy together for people with essential tremor and Parkinson’s disease. Later, when I started working in Switzerland at the Inselspital (university hospital) in Bern, I introduced DBS for treatment of cervical dystonia. We demonstrated its remarkable therapeutic benefits for dystonia and published our first results in The Lancet in 1999. 

Can you explain how DBS works?
DBS therapy is a very complex topic because it triggers a variety of effects. In dystonia, the mechanism of DBS is even more difficult than we initially thought. The clinical effect of DBS stimulation is delayed, especially for the tonic elements of dystonia, which are secondary to sustained muscle contractions. At the same time, when the therapy is maintained, other phenomena are observed like alterations in inhibition and long-term neuroplasticity, which is the ability of neuronal networks to change their functional capacity. We now understand that the delayed effect with DBS is not only secondary to the effect of the chronic stimulation of local neurons and nerve fibres but also to widespread changes in the basal ganglia network and the cortex. We can even record activity from the basal ganglia and demonstrate how the interaction within the network via oscillations in different frequency bands changes. As I said, it is a complex topic.

Is there a need for more research?
Yes, there is. Over the last decades, I have been part of many major studies on DBS and dystonia. Moreover, it has become one of my major points of interest for further research. When a new therapy is first introduced, very few believe the results immediately. However gradually, the DBS-treatment for people with dystonia was getting more widely accepted and about 10 to 15 years after it was introduced, new randomised studies confirmed the initial results. Most of these studies however, have the limitation that they are only conducted for one or two years with no specific focus on long-term follow-up. There is a clear need for more data as we still do not know enough about what will happen after that initial study period. 

In times where research is becoming more expensive and more demanding, registries provide a new window of opportunity; they allow clinicians to monitor patients for a longer time in a formal setting. When Boston Scientific proposed to collaborate on a long-term observational registry including endpoints specifically for people with dystonia, I was very pleased. With professional support, we are able to obtain this important data. 

How does the Vercise™ Registry for Dystonia work?
Back in 2014, Prof. Alberto Albanese and I discussed how we could design such a registry. We agreed we needed to follow at least 200 patients from various hospitals across Europe for 3 years post implantation. In addition, there would be a need to have clear measurable endpoints in place. For this registry, we use a variety of scales to measure these endpoints, such as:

  • Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS – for generalized dystonia)
  • The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS – for cervical dystonia)
  • The Clinical Global Impression of Change Scale
  • Measurements on cognitive function 
  • Measurements on quality of life (QoL)

What makes this registry so important?
We really need this registry as it provides a structured approach to follow-up patients long-term from many medical centres across Europe. In other words, the Vercise™ DBS Dystonia Registry provides us with what is called real-world data, meaning that patients are being treated according to standard of care – personally, I don’t like the term “real-world data”, because it sounds as if clinical studies are not realistic – suggesting that data from these patients under special and controlled study conditions are less valuable.