Well, mana storms tend to have limited durations. When the storm ends, the spell effects end as well. At least, the sustained ones end. A flamethrower manastorm would stop tossing flames, but dead is dead. So you COULD have a manstrom which allowed (or rather force) victims to astrally project. Now imagin having that happen to you and some nasty Storm Wraiths riding the storm and waiting for you on the astral plane. OUCH!. And if the storm lasts for more hours than you have Essence, then you just die no matter what.
Gabriel