Anaesthetics activate

Print edition : November 30, 2012

SCIENTISTS at the Friedrich Schiller University and the University Hospital in Jena, Germany, are researching the use of anaesthetics in therapies for stroke patients.

In The Journal of Neuroscience the researchers presented the results of their study, showing how a local anaesthetic could distinctly improve the motor skills of patients after a stroke. Many stroke patients suffer from chronic impairment of the hand or of the complete arm, Professor Dr Thomas Weiss explained. The psychologist of the Department of Biological and Clinical Psychology at Jena University has, along with colleagues, been working on a specialised medical training therapy which enhances the mobility of stroke patients.

In the Constraint-Induced Movement Therapy, the healthy arm is restrained in a cuff, while the stroke-affected arm and hand are given intense training in fine motor skills. Patients are asked to stack small toy blocks or put tiny pins into a perforated board. Daily activities such as washing ones hand are part of the training. Nearly every affected person benefits from this training, said Prof. Dr Wolfgang Miltner, Weiss colleague.

In addition, the impact of the exercise therapy could be clearly enhanced when the sensitivity of the affected arm was lowered with an anaesthetic. In their study, the scientists examined 36 patients. Half of the patients had a local anaesthetic cream applied on their forearms, whereas the other patient group received a placebo. Both groups went into their exercise therapy for a day.

Unsurprisingly, the motor performance of all patients was strongly enhanced, noted Weiss. Beyond that, it became obvious that the patients who received the anaesthetic benefited even more than the placebo group. The researchers could show the reason for this effect using magnetoencephalographic (MEG) imaging of the patients. The temporary interruption of nerve impulses from the forearm leads to lower levels of activity in the brain areas processing these impulses. At the same time neighbouring brain cells are activated more strongly, he explained. Thus, the brain reacts to the missing impulses from the forearm with an increased sensitivity in the hand as the MEG images showed. Consequently, the motor performance improves as well. This process starts within minutes, said Weiss.

A subsequent study is going to show whether the combination of local anaesthetics and therapeutic exercise will improve the mobility of stroke patients in the long term.

Lyla Bavadam
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