Concussions (also known as mild traumatic brain injury) are common in young children. In some children, they can lead to short- and long-term difficulties. However, our knowledge of the exact consequences of injuries on young children's brains and behavior is limited. These consequences may be different in children under 6, as their brains are fragile and undergoing significant developmental changes.

The aim of this study is to determine the extent to which a concussion sustained before the age of 6 years is associated with changes in young children's brain structure, function and behaviours, using a brain imaging.

In this study, the results of a group of 30 children with a concussion will be compared to those of 30 children of the same age with an orthopaedic injury to the upper or lower limbs.

Inclusion Criteria:

• Patient group with mild traumatic brain injury (mTBI) :

  1. Children aged between 36 months (3 years) and 71 months and 31 days (5 years; before their 6th birthday)
  2. Presentation to the emergency department within 48 hours post-injury
  3. Documented, unintentional traumatic event (e.g. blow, fall, etc.) resulting in non-penetrating head injury
  4. Diagnosis of mTBI (World Health Organization (WHO) paediatric diagnostic criteria)

• Control group with orthopaedic injury:

  1. Children aged between 36 months (3 years) and 71 months and 31 days (5 years; before their 6th birthday)
  2. Presentation to the emergency department within 48 hours post-injury
  3. Documented, unintentional traumatic event (e.g. blow, fall, etc.) resulting in trauma to an upper or lower limb
  4. Diagnosis of simple fracture, sprain, contusion or unspecified trauma to a limb (mild).

Exclusion Criteria:

• Diagnosis of previous TBI (any severity, any age)
• Intentional injury,
• Administration of sedative drugs that can alter brain function
• Complications following injury
• MRI contraindication,
• Parent non-fluent in French,
• Prematurity,
• Diagnosis of a severe neurological, developmental, or psychiatric disorder
• Children in foster care at the time of recruitment

Children aged between 36 months (3 years) and 71 months and 31 days (5 years; before their 6th birthday) with mTBI.

Children aged between 36 months (3 years) and 71 months and 31 days (5 years; before their 6th birthday) with orthopaedic injury (simple fracture, sprain, contusion or unspecified trauma to a limb (mild))