I recently got round to preparing a definition of the word and put it on Wikipedia. The editors there are rather rule-bound and condemned it to deletion as a neologism. It did survive in Wiktionary.
At that time I found that the word existed on Google in only one other place. In an .rtf file written by a Latin scholar. I emailed him to find out where it came from and he told me that it came from an early edition of the Oxford English dictionary but it seemed only to have been defined as the opposite of 'intravolution'.
The word has sound linguistic roots and I have given it a definition. Some people who I have told about this have said that I can't just create/define words. Why not? Must I be an academic to be able to think? Extravolution is a word. I use it and am understood.