Microstructural and Sodium 7 Tesla Brain MRI in Idiopathic REM Sleep Behaviour Disorder

Microstructural Brain MRI Biomarkers in Patients With Idiopathic REM Sleep Behaviour Disorder at 7 Tesla

By 2030 the number of patients with Parkinson's Disease (PD) would increase by 56% affecting 1 out of 120 people older than 45 years-old. It is known that 10-15 years before the onset motor symptoms such as tremor, rigidity and akinesia, patients often experience a specific sleep trouble called REM sleep behaviour disorder (RBD). Follow-up of those subjects showed there was a conversion rate to PD and related disorders (called synucleinopathies) over 80%.

The pathophysiology of RBD is poorly understood. The development of cutting-edge technologies such as 7 Tesla MRI and the optimisation of image processing methods made it possible to non-invasively explore in vivo small brain structures involved in sleep and movement disorders.

The investigators hypothesize that brain and brainstem microstructure, composition, sodium homeostasis and connectivity may change in 15 isolated RBD (iRBD) subjects compared with 15 healthy controls and that these changes may be correlated with clinical scores.

This study would help fill the gap in early diagnosis of synucleinopathies, by contributing to better targeting patients who could be included in therapeutic trials with a neuroprotective effect. Besides, the exploration of original pathophysiological pathways such as sodium homeostatis could provide the necessary arguments for the development of new target therapeutics.

Inclusion Criteria for patients with REM Sleep Behaviour Disorder :

• Patient aged between 40 and 80 years old
• Patient fulfilling the diagnostic criteria for RBD (International Classification of Sleep Disorders version 3, American Academy of Sleep Medicine, 2014) with polysomnographic confirmation (which will be carried out as part of the routine work-up);
• UPDRS Part III score under or equal to 5
• The patient is enrolled in the French social security system
• The patient understood and signed the consent to participate in the study.

Inclusion Criteria for control group :

• Patient aged between 40 and 80 years old
• Score under or equal 4 for the RBD screening questionnaire
• UPDRS Part III score under or equal 5
• The patient is enrolled in the French social security system
• The patient understood and signed the consent to participate in the study.

Exclusion Criteria :

• Patient / Subject with a history of central nervous system disease (e.g. PD, Alzheimer's disease, stroke, brain tumour, multiple sclerosis, amyotrophic lateral sclerosis, etc.). If a doubt exist, this criterion will be left to the judgement of the principal investigator, who is a neurologist.
• Contraindications to 7T MRI: presence of a metal in the body or in the eye, patient with a pacemaker or neurostimulator, cochlear implants or any implanted electronic medical equipment in general, metallic heart valve, aneurysm clips.
• Claustrophobia.
• Montreal Cognitive Assessment Test (MOCA) < 25/30
• Pregnant or breast-feeding woman or protected person (under guardianship, curatorship, deprived of liberty).