There are essentially two general situations. The first one is the patient that has already a diagnosed neurodegenerative disorder – multiple system atrophy, Parkinson’s disease, usually a synucleinopathy, but not necessarily always these type of neurodegeneration – and he develops then symptoms that are suggestive of RBD. In this case it is, in the presence of a typical history, relatively clear that the patient most probably suffers of RBD...
There are essentially two general situations. The first one is the patient that has already a diagnosed neurodegenerative disorder – multiple system atrophy, Parkinson’s disease, usually a synucleinopathy, but not necessarily always these type of neurodegeneration – and he develops then symptoms that are suggestive of RBD. In this case it is, in the presence of a typical history, relatively clear that the patient most probably suffers of RBD. The diagnosis can, pragmatically speaking, try to be made just on history and based off the history, and then it’s more the question of treatment, and treatment today is usually the start of a medication such as clonazepam. This is, I would say, the one situation.
The second one is the patient usually in the second half of his life, 40, 50, 60 years old, that start having symptoms that may be suggestive of RBD, but in the absence of a diagnosis or symptoms suggestive of a neurodegenerative disease. And in this case the diagnosis should be definitely confirmed by video polysomnography. There is a differential diagnosis of RBD. Sometimes nightmares can lead to the wrong diagnosis of RBD. Sometimes nocturnal epilepsy can present with overactivity in terms of behavior and shouting and thrashing around. So in this case, it is important to make a definite diagnosis, and to make a definite diagnosis you cannot just use a history or a questionnaire, but you need to make a video polysomnography. Why? Because if at the end of the diagnostic workup you end up having a definite diagnosis of RBD, then we know that the patient may develop subsequently a neurodegenerative disease, so there is a need to plan further testing and also a follow-up, which may be and is different if the neurodegenerative diseases is already known.