Multiple system atrophy

Multiple system atrophy (MSA) is a rare neurodegenerative disorder which causes autonomic dysfunction, tremors, slow movement, muscle rigidity, and postural instability due to dysfunction of the basal ganglia, and ataxia. 
This is caused by progressive degeneration of neurons in several parts of the brain including the basal ganglia, inferior olivary nucleus, and cerebellum.
The symptoms are closely related to Parkinson's disease.