Leukoaraiosis is a form of cerebral small vessel disease. It is also referred to as white matter hyperintensity (WMH) or white matter lesions.
The term leukoaraiosis was first reported by Binswanger and his student, Alzheimer in the late 19th century.
It has been referred in 1986 by Hachinski, Potter and Merskey to describe a rarefaction (“araiosis”) of the white matter (leuco) located around the ventricles.
These changes are observed using brain imaging techniques such as magnetic resonance imaging or computed tomography.
Leukoaraiosis is not specific to a precise pathological condition. It occurs frequently in elderly patients with ischemic stroke, but also in those with hypertension, vascular dementia, intermittent claudication, or mood disorders.
Several infarcts of small vessels located in the subcortical white matter may be the cause of the condition. Patients may develop subcortical dementia syndrome.
It is estimated that almost all patients with vascular dementia (and about 30 to 50% of Alzheimer’s patients) have leukoaraiosis.
It is also associated in individuals with:
- chronic kidney disease,
- metabolic syndrome,
- coronary artery disease,
- high levels of homocysteine,
- low levels of vitamin B12 and
- high levels of C-reactive protein (a marker of inflammation).
The prefrontal cortex would be particularly sensitive to leucoaraiosis which seems to reduce the speed of information processing in the individual.
Finally, leukoaraiosis is associated with an increased risk of ischemic stroke and cerebral hemorrhage, but also of cognitive decline and impaired gait and motor function, which are clinical hallmarks of subcortical vascular dementia. Up to 80% of patients with leukoaraiosis have gait disturbances.
The risk of dementia increases with the severity of leukoaraiosis.
Leukoaraiosis could be due to poor irrigation of the white matter supplied by the vessels. This poor irrigation is however insufficient to create ischemia.
- female sex,
- high blood pressure,
- heart disease,
- type 2 diabetes,
- abdominal obesity,
- carotid stenosis,
- tobacco use,
- chronic kidney disease.
Some studies have found an association between leukoaraiosis and depression. Patients with leukoaraiosis is varied and includes motor deficits, frequent falls, parkinsonism and pseudobulbar syndrome.
Classification of leukoaraiosis
The Fazekas classification is one of the most widely used. in clinical practice and research. It distinguishes periventricular lesions (around a ventricle) from deep and subcortical lesions. There are 3 grades depending on the severity of the lesions.
- Grade 1: minimal lesions in the form of points (punctiform) or lines. They are isolated or grouped and are less than 20 mm.
- Grade 2: moderate lesions (solitary lesions and more intense areas less than 20 mm in diameter).
- Grade 3: severe lesions (solitary lesions with more intense areas of more than 20 mm in diameter).
This classification distinguishes between periventricular and deep involvement.
Leukoaraiosis is an important risk factor for ischemic stroke and recurrent stroke as well as neurological and cognitive disorders.
Patients with leukoaraiosis therefore require special care.