Original
Multiple system atrophy was previously known by several different names. It was originally thought to be three separate diseases: 1. Striatonigral degeneration - showing mainly parkinson like symptoms 2. Shy-Drager Syndrome - showing mainly autonomic symptoms such as low blood pressure when standing or urinary incontinence 3. Olivopontocerebellar Atrophy - showing mainly cerebellar or ataxia symptoms such as loss of balance and speech and swallowing dysfunction
In 1969 the term multiple system atrophy was adopted to include these three disorders. In 1998 it was discovered that all three diseases had the same brain autopsy finding of alpha-synuclein glial cytoplasmic inclusions (GCIs). These were observed as a build up of toxic alpha-synuclein protein within the oligodendroglial cells (glial cells are a form of helper cells to the neurons that make up the myelin sheath or outer insulating coating of the neurons) within the brain and spinal cord.
Multiple system atrophy is now classified as two separate types: MSA-P (parkinson like symptoms) and MSA-C (cerebellar ataxia symptoms). Both types include autonomic or urinary dysfunction as a defining symptom. You can read the full diagnostic criteria for multiple system atrophy at this link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2676993/