The link for The Ischemic Extremity: New Findings and Treatment
By Heron E. Rodriguez, William H. Pearce, James S. T. Yao
2010
is tricky, you will probably have better luck googling it to read the details , seems it limits views by the link. Can be found on Google books.

If you look at page 500- 502 there are images & descriptions showing middle scalene removal.
So it must be possible to do it and work around the LTN issue successfully.
Quite an interesting book, lots of details on how the various TOS surgeries are done.