The article that I saw said that as she was ducking back into the car her head was knocked into the lever by the shock wave of the explosion. I don't see any reason why that would be implausible, although I am a little surprised that they said that she wasn't hit by any shrapnel. However if her head was at the level of the roof of the car at the time of the explosion, she may well have been protected from shrapnel by the edge of the roof (the bomber was on a motorcycle and would be below the roof line).
I'm not quite sure I see why the precise location of the deadly wound matters at this point.
It is not the location of the wound I find interesting.
It is the changes in stories of what caused the wound.
I am very skeptical of “The Pakistani Interior Ministries” reports.