Setting aside the notion of determining the number of individual animals on the planet for a moment, merely determining the number of species on the Earth is challenging. Science has only been able to offer estimates thus far, and totals vary greatly.
A. A. A. Multiple sclerosis, or MS, is a long-lasting disease that can affect your brain, spinal cord, and the optic nerves in your eyes. It can cause problems with vision, balance, muscle control, and other basic body functions. The effects are often different for everyone who has the disease.
Devic's disease, or neuromyelitis optica, (NMO) is a type of inflammatory demyelinating disease.A demyelinating disease occurs when the myelin sheath, a protective covering that surrounds brain and spinal cord nerves is damaged. NMO is an example of an autoimmune disease. 2  Experts are not sure why autoimmune diseases, such as NMO occur. 3  The immune system of a patient with NMO attacks the myelin sheath, the protective blanket for the spinal cord and optic nerve.