A new way of assessing whether remyelination is taking place may have been discovered by scientists in a study on cats.
Researchers at the University of Wisconsin-Madison measured the speed of the signals sent by the nerves in the eye to the brain using a non-invasive test called visual evoked potential (VEP). This measures the electrical signal passing from eye to brain in response to stimulation with light. It’s commonly used on human subjects and involves electrodes being placed on the scalp which then track the brain activity after the light stimulus.
This test is sometimes used in the diagnosis of multiple sclerosis (MS). An increased delay, known as latency, in the time between a light flash and brain activity indicates myelin damage. But researchers say their experiment could mean that VEP test could demonstrate when remyelination is happening because their research shows a decreased latency.
Remyelination therapy interest is growing, but at the moment the only way to check for the presence of myelin in the central nervous system is to take a sample of nerve tissue, which is too damaging and invasive for patients.
For the research, cats were fed irradiated food and underwent substantial myelin loss, including in their optic nerves. When they returned to a normal diet, the felines recovered lost myelin. VEP measurements were taken throughout the process, and the scientists found improved VEP scores closely correlated with recovery of myelin. This was then confirmed by taking tissue samples.
Researchers say VEP testing could be useful in clinical trials for drugs that aim to repair the myelin, as it’s a viable and non-invasive way to see if the drugs are working. This is particularly important for progressive MS currently has few therapy options.