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.
Geography (from Greek Î³ÎµÏÎ³ÏÎ±ÏÎ¯Î±, geographia, literally earth description) is a field of science devoted to the study of the lands, the features, the inhabitants, and the phenomena of Earth. The first person to use the word Î³ÎµÏÎ³ÏÎ±ÏÎ¯Î± was Eratosthenes (276â194 BC).