This is a retrospective cohort study aiming to determine whether the use of Dexmedetomidine (DEX) to sedate children prior to MRI scanning is more or less effective in children with autism spectrum disorders or other neurodevelopmental disorders compared to other children.

Performing brain MRI on children under 5, or in cases of autism or disability, is often complex. In fact, this examination requires total immobilization of the child for at least 20 minutes. The noise and the fact that the child is lying in a sort of tunnel add to the child's stress.

General anesthesia with propofol is widely used in France, but requires invasive orotracheal intubation or mask ventilation. There are no national or international recommendations for pediatric MRI sedation procedures.

Intranasal dexmedetomidine (DEX) is used for brain MRI, cardiac ultrasound, ophthalmology, dental treatment and brain computed tomography (CT) in patients aged 3 months to 12 years. Its superior efficacy has been demonstrated in a number of studies compared with the most commonly used medicated procedural sedation techniques, but only one study in France has prospectively analyzed the efficacy of DEX IN for performing cerebral MRIs, but without assessing efficacy and tolerance in subgroups of children: with or without neurodevelopmental disorders, epilepsy, autism, age.

Inclusion Criteria:

• patients under 18 years of age sedated with DEX IN prior to MRI.

Exclusion Criteria:

• incomplete or missing medical records

patients under 18 years of age sedated with DEX IN prior to MRI.

According to the French law and the French Data Protection Authority (CNIL), it is not possible to share publicly individual participant data, but only their conclusions through peer-reviewed publications and conferences.