Merkuri
Explorer
Aphasia: The affected person loses the ability to understand and communicate spoken or written words.
One mechanical way to represent this may be that the affected character never counts when figuring out flanking. Perhaps the character also cannot be affected by certain bonuses from other party members (such as warlord powers, which are often PR'd as encouraging language).
Obsessive - You repeat the same standard action each turn. If you could not normally repeat it because the power wasn't at-will, you do repeat it, but lose a healing surge.
That one could be dangerous to game balance. Someone who happens to be obsessively repeating a daily could easily break the game. Losing a healing surge may not be enough of a detriment to cancel that out.