Demyelination is often secondary to an infectious, ischemic, metabolic, or hereditary disorder or to a toxin (eg, alcohol, ethambutol). In primary demyelinating disorders, cause is unknown, but an autoimmune mechanism is suspected because the disorder sometimes follows a viral infection or viral vaccination.
For other uses, see Realm (disambiguation). A realm /ËrÉlm/ is a community or territory over which a sovereign rules; it is commonly used to describe a kingdom or other monarchical or dynastic state. The Old French word reaume, modern French royaume, was the word first adopted in English; the fixed modern spelling does not appear until the beginning of the 17th century.
A captivating subject, geography is a scientific field that is devoted to the study of the Earthâs landforms, oceans, environment and ecosystems, and the interactions between the human society and their environment. The word geography literally means âearth writingâ.