Why did headbutting Gaara make Shukaku disintegrate?


When Naruto is fighting Gaara in the invasion of Konoha, Gaara takes on the
Perfect Possession form of Shukaku. When Naruto punches Gaara in the face, it
wakes him up, breaking the Possum Jutsu and making Shukaku no longer be
released. When Naruto headbutts Gaara, however, Shukaku disintegrates. What
causes this difference in effect?




I think Gaara just lose control over the chakra flow when Naruto headbutted
him. With that, he couldn't keep the jutsu which showed the body of Shukaku.

