Feasibility of Vision-Language Models for Detecting Physical Assistance as an Observable Criterion Defining GMFCS Levels in Children Aged 2 to 6 Years With Cerebral Palsy

The GMFCS sorts children with cerebral palsy into five levels of gross motor function. What mainly separates one level from the next is two things an observer can see: whether another person has to physically help the child move, and whether the child has to bear weight on something external, such as a walker, a support stand, or furniture. Scoring these takes an experienced clinician, and it is hardest between the ages of 2 and 6. This study asks a narrow question. Can a vision-language model, meaning an artificial-intelligence model that looks at images and answers questions about them, detect those two things from short video clips of a child moving? Twenty-six children with cerebral palsy aged 2 to 6 years were filmed at two hospitals. Each child performed everyday movements, including walking, crawling, rolling sideways, rising from the floor to standing, and lowering back to the floor, and up to three cameras recorded every attempt at the same time. Sixteen still frames were taken from each recorded attempt, always sixteen, and shown to the model without the child's identity, the name of the movement, or the child's GMFCS level. The model answers two yes-or-no questions and nothing else: did an adult touch the child, and did the child bear weight on an external object. A fixed rule, not the model, turns those answers into one determination per attempt, namely whether the child performed the movement unaided. These determinations are compared with what a human annotator recorded for the same clips while blind to clinical information. All rating is done with open-weight models running on hardware the investigators control, and every reported figure is tied to the specific model version that produced it. The study does not assign a GMFCS level, and it is not built to. It tests whether the two observations the GMFCS itself relies on can be read from video reliably. If they can, they can be placed in front of a clinician as evidence, which is where later work on supporting GMFCS assessment would start.

Inclusion Criteria: * Clinical diagnosis of cerebral palsy * Aged 2 to 6 years at the time of video recording * Under the care of the department of physical and rehabilitation medicine at Samsung Medical Center or Asan Medical Center * A GMFCS level assigned by the treating clinician * Written informed consent from a parent or legal guardian for video recording Exclusion Criteria: * Consent for video recording is not given * GMFCS level cannot be clearly assessed * The child or the parent or legal guardian declines to take part in the study Withdrawal Criteria: * The child or the parent or legal guardian requests withdrawal during the study * The collected video is not of adequate quality for analysis * The participant's health status changes substantially during the study period