[perihelions]

It's a neurological sign associated with traumatic brain injury. That unnatural reflex of the arms you can see in that video.

https://en.wikipedia.org/wiki/Fencing_response ("Fencing response")

[rossant]

Thank you. So haunting.

[perihelions]

It's useful to recognize that pose! It's often people who could benefit from quick medical attention, if someone notices the symptom.