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The MRI of patients with VWM shows a well defined leukodystrophy. These MRIs display reversal of signal intensity of the white matter in the brain. Recovery sequences and holes in the white matter are also visible. [4] Over time, the MRI is excellent at showing rarefaction and cystic degeneration of the white matter as it is replaced by fluid.
Demyelinating lesions begin with the appearance of some areas named NAWM (normal appearing white matter) which despite its name, is abnormal in several parameters. These areas show axonal transections and stressed oligodendrocytes (the cells responsible for maintaining the myelin), and randomly, they show clusters of activated microglia named ...
A fourth area called DAWM (diffusely abnormal white matter) has been proposed [116] and can help to differentiate PPMS and SPMS. [117] Abundant extracellular myelin in the meninges of patients with multiple sclerosis has been found [118] Brain tissues with MRI-hidden problems are usually named Normal Appearing.
It is not known what causes MS. Several problems appear together with the white matter lesions, like cortical lesions and normal-appearing tissues. Several theories have been proposed to explain it. Some areas that appear normal under normal MRI look abnormal under special MRI, like magnetisation transfer MTR-MRI.
White matter is the tissue through which messages pass between different areas of grey matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons). This myelin is found in almost all long nerve fibers, and acts as an electrical insulation.
T2 weighted axial scan of a human brain at the level of the caudate heads demonstrates marked loss of posterior white matter, with reduced volume and increased signal intensity. The anterior white matter is spared. Features are consistent with X-linked adrenoleukodystrophy. Specialty: Neurology
The volume and frequency is strongly associated with increasing age. [2] They are also seen in a number of neurological disorders and psychiatric illnesses. For example, deep white matter hyperintensities are 2.5 to 3 times more likely to occur in bipolar disorder and major depressive disorder than control subjects.
MRI image: Leukoaraiosis in a 90-year-old patient with cerebral atrophy. Head CT showing periventricular white matter lesions. Leukoaraiosis is a particular abnormal change in appearance of white matter near the lateral ventricles. It is often seen in aged individuals, but sometimes in young adults.