I read that among various corruption risks is the filesystem corruption, that also affects TrueCrypt volumes, like any other system.I would like to know if it is possible that a corruption in some special small region can lead to lose the entire filesystem?
TrueCrypt: filesystem corruption: is it possible to lose all data at once
Yes, there is one critical part in a TrueCrypt volume that has to be present and valid otherwise your data is lost: The Volume Header
This is the reason why TrueCrypt has the possibility to back-up this small region and save it somewehere else:
Select Tools -> Backup Volume Header
The Volume Header is really small it's - the first 512 bytes of the TrueCrypt container.