Narration script software for MS Powerpoint?


I am currently doing a number of PowerPoints which require narration. Out of sheer laziness, I just type down straight into the Comments section. However, the difficulty is that I would like to pass the PowerPoint to the editor for proofreading and editing while working on the powerpoint at the same time. There is a difficulty in synching the edited script with the PowerPoint.

Is there a plug-in or a module for PowerPoint that aids in writing scripts for narration and featuring an easy way to import and export text?

Thanks in advance!