MYELITIS ([Gk.] muelos, marrow) is a disease which by inflammation includes destructive changes in the tissues composing the spinal cord.

In the acute variety the nerve elements in the affected part become disintegrated and softened, but repair may take place; in the chronic form the change is slower, and the diseased area tends to become denser (sclerosed), the nerve-substance being replaced by connective tissue.

Myelitis may affect any portion of the spinal cord, and its symptoms and progress will vary accordingly. Its most frequent site is in the lower part, and its existence there is marked by the sudden or gradual occurrence of weakness of motor power in the legs (which tends to pass into complete paralysis), impairment or loss of sensibility in the parts implicated, nutritive changes affecting the skin and giving rise to bed-sores, together with bladder and bowel derangements. In the acute form, in which there is a first pain in the region of the spine and much constitutional disturbance death may take place rapidly from extension of the disease to those portions of the cord connected with the muscles of respiration and the heart, from an acute bed-shore which is very apt to form, or from some inter-current disease.

Recovery to a certain extent may, however, take place; or, again, the disease may pass into the chronic form. In the latter the progress is usually slow, the general health remaining tolerably good for a time, but gradually the strength fails, the patient becomes more helpless, and ultimately sinks exhausted, or is cut off by some complication.

The chief causes of myelitis are injuries or diseases affecting the spinal column, extension of inflammation form the membranes of the cord to its substance (see MENINGITIS), exposure to cold and damp, and occasionally some pre-existing constitutional morbid condition, such as a fever. Any debilitating cause or excess in mode of life will act powerfully in predisposing to this malady. The disease is most common in adults.

The treatment for myelitis in its acute stage is similar to that for spinal meningitis. When the disease is chronic the most that can be hoped for is the relief of symptoms by careful nursing and attention to the condition of the body and its functions. Good is sometimes derived form the employment of electricity, and the use of baths and douches to the spine.