Patients who suffer from multiple sclerosis (MS) typically present with centers of inflammation in the brain and spinal cord, which cause symptoms that range in severity depending on site and size. For example, sufferers feel a tingling sensation in their extremities, they stumble more or they have difficulties seeing. In extreme cases, they become incapable of moving around on their own and are confined to a wheelchair.
How the brain compensates for damage
The brain, however, often manages to minimize the functional damage caused by such centers, i.e. the damage that is noticeable to the patient. It has various “tools” at its disposal for this purpose: firstly, processes that are based on a rapid reinforcement or reduction of nerve cell contacts; secondly, the transfer (usually with a delay) of certain tasks from the damaged region of the brain to a healthy one. “Plasticity” is the name science has given to this ability on the part of the brain to adapt to changed conditions.
The answer to the question as to which mechanisms actually underlie this compensation in MS patients is of great clinical value. If medicine were to manage to boost the compensation mechanisms in a suitable location with the help of drugs or physiotherapy, it might be possible to delay or even prevent the onset of disabilities that are caused by MS.
Plasticity in the locomotor system
Now scientists from the University of Würzburg have managed to make some progress in the search for the processes responsible. Together with colleagues from Bamberg and Leipzig they have taken are closer look at a variant of the neuroplastic processes that begin rapidly: the so-called excitability-decreasing plasticity, which is significant in the focus on certain movements. The team led by the medics Professor Joseph Claßen and Dr. Daniel Zeller has now published its findings in the online journal BioMed Central – Neurology.
“We were able to show that an early form of neuroplasticity is fully retained in the locomotor system of patients slightly to moderately affected by MS despite pre-existing inflammatory damage,” concludes Daniel Zeller, physician at the university’s Department of Neurology.
14 MS patients and a control group of 14 healthy participants were examined by the scientists as part of this study. With the help of Transcranial Magnetic Stimulation (TMS), they temporarily “paralyzed” an area of the brain that is responsible for hand movement and then examined whether “healthy brains” and “MS brains” differ in their response to this. “Studying this form of plasticity in multiple sclerosis is especially interesting,” says Zeller. After all, it directly targets those mechanisms that limit the excitability of neurons. This means that it might be possible to translate the results directly into treatment strategies.
So, what do these results reveal? “Together with the findings of an earlier study we conducted we can say that there is no evidence that the early stages of MS are accompanied by a disruption of the initial compensation steps in the brain,” says Zeller.
In terms of rehabilitation for sufferers this means that it would be better if corresponding approaches were aimed at boosting later forms of plasticity, such as the recruitment of other regions of the brain for the execution of a certain task.
About multiple sclerosis
The “disease with 1000 faces” is how multiple sclerosis (MS) is sometimes described. The reason for this name is that the clinical picture can differ dramatically from patient to patient – in terms of both the progression of the disease and the symptoms suffered.
However, there is one finding that is the same in principle for everyone: multiple sclerosis is an autoimmune disease where one particular type of brain cell, known as an oligodendrocyte, is destroyed by the immune system. Oligodendrocytes form an insulating layer around the extensions of nerve cells that is required for efficient impulse conduction. If this conduction is disturbed as a consequence of damage to the insulating layer, the nerves cannot transfer relevant “messages” as effectively as before.
According to the Multiple Sclerosis Society of Germany, around 2.5 million people worldwide have MS. The latest projections indicate that some 130,000 sufferers live in Germany; around 2,500 people are diagnosed with the disease each year.
Excitability decreasing central motor plasticity is retained in multiple sclerosis patients. Daniel Zeller, Su-Yin Dang, David Weise, Peter Rieckmann, Klaus V Toyka, Joseph Classen. BMC Neurology 2012, 12:92 doi:10.1186/1471-2377-12-92
Dr. Daniel Zeller, T: +49 (0)931 201-23115, e-mail: Zeller_D@klinik.uni-wuerzburg.de