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?
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.
According to the truecrypt FAQ, the cipherblock size is 16 bytes, so one bad bit will likely cause the loss of 16 bytes, but not the whole disk.