"Not only should I" in declarative sentence [duplicate]

There is a phrase "Not only should I succeed but others should fail". And I saw it many times in similar structures that the order of words "should I" are as if they were in a questioning sentence. (In a declarative sentence the order is "I should")

Can anyone give me an explanation why that is?

I don't know the specific grammatical rule for this, but it is common to invert subject and verb when adverbs or adverb phrases are placed at the beginning of a sentence. See more here:

http://www.englishgrammar.org/inversion-subject-verb/#udVqaYOcOyIydwVs.99

and here:

http://en.wikipedia.org/wiki/Inverted_sentence