The meaning of 一本 in these lyrics


I am trying to translate a song and it's pretty difficult one and I'm unsure
just what kind of meaning these lyrics have:

> この手を伝う 一本の孤独は  
>  人の色が 褪せたままで

My problem is with 一本 because I have always used it as a counter and the word
after this is 孤独, so I don't quite understand well. I looked up on Jisho and
there is this meaning of: "single-minded focus on ...​"  
Can someone give some examples and a better explanation when it's used this
way, when it is not used as a counter?




If this is from [this
song](http://www.utamap.com/showkasi.php?surl=k-180801-079), "一本の孤独 that runs
on my hand/arm" refers to his [radial
artery](https://en.wikipedia.org/wiki/Radial_artery) (or maybe a red line made
by the flowing blood). This is not an idiomatic phrase nor a common metaphor,
so you just need to understand the whole context of this song. 一本気 is not
relevant at all.

