In its classic definition, by FranÃ§ois-Louis Ganshof (1944), feudalism describes a set of reciprocal legal and military obligations among the warrior nobility revolving around the three key concepts of lords, vassals and fiefs.
The exact cause of intracardiac echogenic foci remains unclear; however, they appear to be caused by small deposits of calcium in the papillary muscle of the fetal heart.
1 NMO most often causes visual changes in both eyes and symptoms caused by long lesions in the spinal cord.  Acute disseminated encephalomyelitis (ADEM) â A brief but intense attack of inflammation in the brain, spinal cord and occasionally the optic nerve that causes damage to myelin. Symptoms of ADEM come on quickly, often beginning with behavior changes.