The subject is written in a way to try and avoid any spoilers, if you think it should change: feel free.
What does Henry Injects to Adam's neck in order to paralyze him?
In the TV Series Forever S01E22 after Adam shoots Henry with the musket (that theoretically is the one responsible for Henry's immortal state) Henry injects something to Adam, which after, in the hostpital scene, we learn that Adam is now paralyzed.
What actually cause that effect?
Is it reversible?