Our Sorcerer was hit by massive Int drain, to the point that she had an effective Int of 2. Between then and the time we could fix her Int drain, could she cast spells?
There are two obvious factors:
To cast a spell, you must be able to speak (if the spell has a verbal component)...
Having a low Intelligence means that you can't understand language:
Creatures of animal-level instinct have Intelligence scores of 1 or 2. Any creature capable of understanding speech has a score of at least 3.
Thus, she would not understand the words necessary to fulfil the verbal components of her spells.
However, the Sorcerer:
can cast any spell she knows without preparing it ahead of time. To learn or cast a spell, a sorcerer must have a Charisma score equal to at least 10 + the spell level.
Thus, the verbal components need not necessarily be intelligible speech, just words that "feel right" for the spell (borrowing from the Dresden-verse a bit). And, while she didn't understand language, she still had all of the physical equipment to produce language's sounds.
Tactics, targeting, etc. aside, do RAW speak specifically to an extremely-low Int spontaneous caster's ability to cast?