The white matter of the brain are the nerve fibres (coated in myelin sheaths) that conduct nerve impulses quickly throughout the brain and spinal cord. The white matter connects various grey matter areas of the brain to each other. The myelin acts as an insulator, and increases the speed of the nerve impulses.
White matter disease (WMD) describes the changes in the white matter of the brain caused by Chronic Small Vessel Disease (CSVD), and therefore has the same risk factors (ageing, high blood pressure, diabetes)
In older people, white matter changes are a normal part of aging. In younger people, it is indicative of a disease process. Possible causes include stroke, migraine headaches, inflammation, multiple sclerosis and other demyelinating diseases.
White matter disease also significantly increases a person’s risk of having a major stroke. The factors vary from study to study, with the lowest estimates being twice the normal risk. One study states white matter disease is responsible for one fifth of all strokes. White matter disease also increases the risk of developing vascular dementia or Alzheimer’s disease.
What are the Symptoms of White Matter Lesions
Once thought to be a benign finding, recent studies have shown that white matter changes are associated with:
Increased risk of stroke and death
The severity and type of symptoms is dependent on the number and location of the white matter lesions. Some cases are very mild with no symptoms, while others are more severe.
Causes of periventricular white matter lesions
Age is the most common cause. White matter lesions are a natural consequence of ageing. Studies have shown that 30% of people over 65 will have white matter changes on MRI, and the incidence rises with age.
It is much more unusual in a younger person, however. Other causes include:
High blood pressure/Small strokes: Multiple small Strokes caused by high blood pressure are strongly associated with periventricular white matter disease. Small bleeds in the deep areas of the brain cause damage to the small arterial vessels, and cause white matter lesions.
Diabetes: High glucose levels cause damage to the small vessels in similar ways to high blood pressure, above.
MS and demyelinating diseases: Multiple sclerosis and other similar demyelinating diseases cause white matter lesions of the brain.
Inflammation: Studies show white matter disease is a common finding on MRI in patients with Systemic Lupus Erythematosus, as are lacunar infarcts.
Treatment of white matter disease
Treatment is aimed at reducing risk factors; controlling high blood pressure and lowering cholesterol and blood sugar.