Rowan has been diagnosed with PTA - Post Traumatic Amnesia. This is a normal phase people with brain injuries go through with a number of possible behaviours. Rowan may experience none, some, or all of the behaviours to some degree or another ... it just depends. Each patient is different.

As you know, his is a severe brain injury, he's not responding to command, and he's not really communicating, so his PTA phase will be longer than if it were a mild brain injury, but there's no way of knowing exactly how long it might be. Likely "weeks".

During this time, it is recommended that visitors ...

• Talk in soft, calm voices.
• Speak slowly and clearly to him, and be prepared to repeat things.
• Read calm material quietly. Listen to soft, slow music. Show him photos.
• Have some familiar items in the room, but not clutter.
• Don’t bombard him with stimulus. For example, TV or movies would probably not be a good idea right now.
• Keep room quiet and lights dim.
• Restrict visitors.

There is lots on Google about PTA.