Inherited Leukoencephalopathies

Leukoencephalopathies are disorders that selectively involve the white matter of the brain. Acquired causes of leukoencephalopathy include inflammatory, infectious, vascular, neoplastic, and toxic disorders. Hereditary leukoencephalopathies encompass conditions characterized by progressive destruction or loss of previously acquired central myelin (leukodystrophies) and conditions associated with impaired formation of myelin (dysmyelination or hypomyelination). The study of clinical features, neuroimaging patterns, and biochemical and neuropathologic features of leukoencephalopathies has led to the discovery of the genetic defects responsible for many of these conditions. Variations in phenotype-genotype correlation can make prediction of the underlying condition challenging. Despite recent advances in molecular studies, approximately 50% of patients with hereditary leukoencephalopathies remain without a diagnosis. A systematic approach to guide investigations is important for a diagnosis.

Osmotic Demyelination: From an Oligodendrocyte to an Astrocyte Perspective

Osmotic demyelination syndrome (ODS) is a disorder of the central myelin that is often associated with a precipitous rise of serum sodium. Remarkably, while the myelin and oligodendrocytes of specific brain areas degenerate during the disease, neighboring neurons and axons appear unspoiled, and neuroinflammation appears only once demyelination is well established. In addition to blood‒brain barrier breakdown and microglia activation, astrocyte death is among one of the earliest events during ODS pathology. This review will focus on various aspects of biochemical, molecular and cellular aspects of oligodendrocyte and astrocyte changes in ODS-susceptible brain regions, with an emphasis on the crosstalk between those two glial cells. Emerging evidence pointing to the initiating role of astrocytes in region-specific degeneration are discussed.

Myelin Oligodendrocyte Glycoprotein Antibody Associated Transverse Myelitis

Antibodies against myelin oligodendrocyte glycoprotein cause inflammatory lesions of central myelin – in optic nerves, of the brainstem, and spinal cord. There are characteristic changes of CNS white matter, protein-cytological association in cerebrospinal fluid, MOG IgG antibodies, a very important differential diagnosis and a relatively mild course.