Parkinson's Disease is sometimes also called Idiopathic Parkinson's Disease, basically meaning of unknown origin, while PS or parkinsonism mainly refers to a condition on the Parkinson's spectrum that has a known origin, like exposure to particular chemicals, maybe from industrial or work related exposure, or medication, or as a result of TIA's,injury or illness,etc. among several other things. PS is sometimes considered to be either less responsive or non-responsive to dopamine replacement therapies dependent on origin of the condition. There are also Parkinson's plus conditions, of which there are several. They are a range of symptomatically similar conditions that over time differentiate into more recognizable and nameable conditions, that have characteristics of their own. PD itself is by no means clearly defined or definable, and when a diagnosis is unclear it is quite often called atypical, though that is a word that can sometimes be used for PS and P+ type conditions too, making the terminology slightly confusing. All in all IPD is difficult to diagnose, MRI's are used to exclude other conditions, and PET scans are used to firm up an IPD diagnosis or rule it out. Even so a diagnosis is usually arrived at through a combination of scans and long term observation, unless there are unequivocal signs that PD or another parkinson's type condition is present, which does sometimes happen!

Many of us have learned through experience that diagnosis and treatment can take time to get 'right', and some of us live with a 'possible' or 'probable' diagnosis. If your mother responds well to the medication (sinemet) she has been prescribed it is likely, though not definite, that she has PD.

While there is a process of elimination that goes on, it is unlikely that 'all other options' can be excluded completely at such an early stage, so the aim will be to get as close as possible and find a treatment regime that gives the best possible quality of life.

Hope this helps
Lindy