Multiple system atrophy (MSA) is a sporadic neurodegenerative disorder. MSA is dominated by autonomic/urogenital failure which may be associated with either Parkinsonism (MSA-P subtype) or with cerebellar ataxia (MSA-C subtype). The prognostic of this disease is bad because it ended with the patient's death few years later. No neuroprotective treatment has shown a real efficacy. 50% of patients suffering of MSA frequently experienced painful sensation. The origin of this pain is unknown. In Parkinson disease (PD) ; arguments suggest the implication of dopamine neuromediator pathway in integration and modulation of pain. Several studies suggest the existence of various influences with dopamine implication in the appearance of painful sensation and that would be inhibitory. That's why observed painful symptoms in MSA and PD could be due to a decrease of pain appearance threshold, secondary to a lost of control of sensitizes centres, to Parkinson control.

It is interesting to determine if MSA as PD is responsible for a decrease of pain threshold and to characterise the levodopa effect on the patient's pain threshold. Better physiopathology knowledge of pain in MSA is necessary to improve the therapeutic care. Because the efficacy of others treatments is low, it's important to improve the research for a better comfort of patients with a better understanding, analysing and treating of the pain.

Inclusion Criteria:

• Patients from 50 to 80 years old (Male and female)
• Patients suffering of a diagnosis possible or probable MSA-P with the international criteria (2008).
• Patients with clinical diagnosis of Parkinson's disease according to the criteria of the UKPDSBB (Gibb et Lees, 1988; Hughes et al, 1992)
• Patients with no cognitive troubles
• Patients who give their informed and signed consent.
• Patients affiliated to a social protection program

Exclusion Criteria:

• Patient suffering from an other parkinson syndrome than MSA and PD, by example progressive supranuclear palsy, corticobasal degeneration…
• Patient suffering of a diagnosis possible or probable MSA-C with the international criteria
• Patient suffering from another pathology causing chronic pain (rheumatic disease, traumatic or orthopedic pathologies…)
• Patient under tutelage, curatella or law protection