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.
Brain cell death or malfunction: The cause of certain brain lesions, like those seen with Parkinson's disease, are due in part to the malfunction and death of brain cells that produce dopamine. However, the underlying cause may be related to genetics, toxic exposures, or various other combinations of potential causes.