I'm not sure there is a connection between perineural invasion and
bundle excise.  Almost everyone has perineural invasion (a statistical
non-issue) and almost everyone has "nerves spared".  Do they remove the
nerves when there is perineural invasion?  If so, a lot of us who opted
for nerve-sparing surgery were hood-winked when the docs said "we were
able to spare the nerves" when the path report states flat out that
there was perineural invasion.  Maybe it's no wonder there are so many
limp Willies.
Dave Perry

Perineural invasion refers to nerves inside the prostate, not to the
nerves which control erections which are outside the prostate.   The
nerves inside the prostate would of course be removed along with the
prostate.  Nerve sparing surgery attempts not to cut or damage the
nerves controlling erections, which are close to the prostate.  Great
skill is required to remove everything which might contain cancer and
still leave those ertile nerves undamaged.   Sometimes it is not
possible.  In that cases, some surgeons will try to graft a nerve from
the leg in the same area hoping it will take over the function of the
damaged nerve.  Often a plastic surgeon will do that part of the
procedure.  As far as I know, there is no connection between a finding
of perineural invasion and the likelihood of ending up impotent after
surgery.

Perineural invasion may suggest that the cancer is closer to the
prostate capsule and hence more likely to penetrate the capsule.  But
there is a lot of disagreement about how important it actually is in
diagnosis when found in the initial biopsy.  After surgery, the
pathologist has more direct ways to tell whether or not the cancer was
confined to the prostate, so at that point a finding of perineural
invasion, which is very common, is presumably not too interesting.