You get into Intensive Treatment same way you did late in the story - line across to the upper entrance from one of the sniper towers. You could also get in via the caves through the door where you saw Croc earlier. Same thing for door to Arkham West, go through the hole you blasted with the gel shortly after you first obtained it.
Full Answer
What is the intensive treatment center in Arkham Asylum?
The Intensive Treatment Center was the initial building of Arkham Asylum. It housed Holding Cells, a Patient Pacification Chamber, and even a Decontamination Room. Originally, the center was a factory before the asylum had been constructed.
What is Batman Arkham Asylum?
Batman: Arkham Asylum brings the universe of DC Comics’ detective to life with stunning graphics.
How do I get to the upper entrance to Arkham North?
The upper entrance in the south area of Arkham North can be accessed by Line Launching from one of the sniper towers. 1. Joker Teeth x10 2. Joker Teeth x5
How do I get to intensive treatment for riddle solving?
To return to Intensive Treatment for Riddle solving later in the game, you'll need the Line Launcher. The upper entrance in the south area of Arkham North can be accessed by Line Launching from one of the sniper towers. 1. Joker Teeth x10 2. Joker Teeth x5 3. Chronicle of Arkham
3. Chronicle of Arkham
In the Transfer Loop, search for a grate up high in the eastern area (use Detective Mode to reveal it in orange). It leads into the center of the tall shaft at this end of the area. Pull it down with the Batclaw when you get it and grapple up. Follow the shaft back to the marker.
4. Chronicle of Arkham
In the destroyed elevator shaft in Secure Transit, near the top you'll find a Chronicle of Arkham marker along the wall in plain sight.
5. Chronicle of Arkham
About half way up Secure Transit Area shaft you'll find a platform with a low-hanging beam. Crawl under this and move towards the south wall to find some destructible panels. Mine them with Explosive Gel and scan the marker behind on of them.
6. Joker Teeth x20
You can find some of these tricky teeth in the south end of the Transfer Loop and in the halls north of Decontamination. There are teeth in offices near the very start of the game as well.
9. Riddler Trophy
Processing Corridor -- You'll see a vent along the bottom of the wall highlighted in orange. Approach it, remove it and crawl inside to find a Riddler Trophy. This unlocks the Riddler Character Profile.
10. Riddler Trophy
In the northeast section of Decontamination is a security door. Hack it with the Cryptographic Sequencer (once you get it) to gain access to the office beyond. Climb up the ladder to score a Riddler Trophy.
13. Mystery (Intensive Care Secrets Map)
After you open the very bottom portion of the Secure Transit area (beat the third Scarecrow sequence -- in Intensive Care), take the stairs up into the control room on the north side. Here you'll find the Intensive Treatment Secrets Map sitting on a desk.
What was the initial building of Arkham Asylum?
The Intensive Treatment Center was the initial building of Arkham Asylum. It housed Holding Cells, a Patient Pacification Chamber, and even a Decontamination Room. Originally, the center was a factory before the asylum had been constructed. There had been many suicides reported there.
Who liberated the Intensive Treatment Center?
Batman followed Scarecrow back into Secure Transit and defeated the remaining henchmen. The Intensive Treatment Center was liberated by the GCPD as the police retook control of Arkham Island after the Joker's defeat.
Who was the Joker holding hostage in the decontamination chamber?
Joker continued to the Decontamination Chamber while the remaining security personnel were preoccupied with trying to recapture Victor Zsasz, who had already murdered a guard in the Patient Pacification Chamber and was holding another, Mike, hostage.
Who was the security guard in Batman?
Another security guard, Henry Smith, attempted to follow them, and found that someone had jammed the elevator controls. On the upper level, a team of Joker's Henchmen had seized control of the elevator area, which had been further disabled by Harley Quinn in an effort to slow Batman down.
How did the Joker escape?
The Joker escaped through Extreme Isolation, and the sole surviving security guard was not able to allow Batman through, due to the fact the Joker had rendered the computerized transport system to Extreme Isolation unusable.
Intensive Treatment
Just as you enter the area, head into the nearby vent after removing the grate. Crawl north and enter the next vent towards the visible Riddle Trophy. Hop up onto the vent and drop into the cage with the Riddler Trophy to snag it ( Intensive Treatment #30) .
The Scarecrow Part III
Just inside the next area DON'T PANIC -- and do not adjust your video game console! The Scarecrow now will introduce a cutscene of his own insidious devising. Just walk forward and play along.
Killer Croc
Killer Croc is adept to using this watery environment to his advantage. As Batman walks the boards, he'll be able to sense your movement -- this means you shouldn't run unless you want to attract trouble. You can, however, crouch to move quickly without causing too many sound waves.