MYELITIS. A medical term for destructive changes in volving the spinal cord. As the termination "itis" indicates, these changes formerly were regarded as inflammatory, but it is now known that although the spinal meninges are affected by inflam mation, nervous substance is rarely, if ever, "inflamed" because of its paucity of blood-vessels. On the other hand, its nutrition is readily impaired by morbid processes in its neighbourhood, and it degenerates or dies and undergoes softening. Myelitis is such softening of the spinal cord, local or widespread, affecting a por tion of the cord or its whole thickness, and the symptoms to which it gives rise depend upon the site and extent of the lesion. It may run a rapid or a chronic course, and in the latter instance the de generated nerve substance may be, in whole or in part, replaced by proliferated neuroglial tissue which is of the nature of a scar.
Any part of the cord may be affected, but it is commoner in the lower half. It leads to paralysis of lower limbs and other muscular parts by interference with conductivity in the white matter of the cord, and to nutritive changes by destruction of the cells in the grey matter. It causes loss of sensation below the level of damage, and often a zone of hyperaesthesia just above that level. If acute it is often followed with great rapidity by bed sores of great size and depth, and incontinence of urine and faeces, partic ularly when the lumbar cord is affected. The chief causes are in juries and diseases of the vertebrae or meninges leading to pres sure on the cord, particularly syphilis. The disease principally affects adults. As might be anticipated, treatment is unsatisfac tory and is directed towards relief of symptoms. (W. S. L.-B.)