Our brains consist of grey matter and white matter. Grey matter contains the nerve cells, while white matter is composed of nerve fibres, which connect the nerve cells and are protected by myelin. Myelin is needed for our nerves to work properly.
When the myelin sheath is damaged, the flow of impulses along nerve fibres slows down or fails completely. As a result, brain functions become hampered or are lost.
MS has long been considered a disease of white matter, but more recent studies have highlighted the importance of grey matter demyelination.
Grey matter is classed as either superficial or deep. The superficial grey matter, also called brain cortex, is on the outside of the brain. The deep grey matter is made up of neurons from which originate deep nerve fibres. These neurons tend to form clumps of basal nuclei.
The presence of lesions in deep grey matter nuclei has been described in several studies.
MRI studies, for example, have shown atrophy in the deep grey matter of people with MS. Furthermore, atrophy of the basal nuclei has been linked with clinical disease progression.
Recent studies have suggested that a number of factors, like iron accumulation, may be involved in MS plaque formation and damaging grey matter cells. We also know that the basal nuclei have the highest iron content in the human brain.
In a study recently published in the Journal of Neurology, Neurosurgery and Psychiatry, researchers from the Medical University of Vienna analyzed deep grey matter from brain autopsies of 75 MS patients and 12 people without MS.
The researchers showed that the deep grey matter is profoundly involved in the disease progression of MS patients and appears to contribute significantly to the build-up of disability.