Brian P. Jacob, David C. Chen, Bruce Ramshaw, Shirin Towfigh (eds.) - The SAGES Manual of Groin Pain-Springer International Publishing (2016)

1. Introduction to Primary and Secondary Groin Pain…
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include chronic relapsing appendicitis or diverticulitis, IBD, adhesions,
orchitis, prostatitis, and in women, round ligament pain, endometrioma,
and endometriosis—to name a few.
When it comes to discussing secondary groin pain, a few definitions
are helpful. Nociceptive pain is caused by activation of nociceptors by
nociceptive molecules due to tissue injury or inflammatory reaction.
These signals are then transmitted to the brain via A-delta and C-fibers.
Neuropathic pain is caused by direct nerve injury due to direct contact
of nerves with mesh and/or nerve entrapment by sutures, staples, tacks,
folded mesh, or meshoma. For complex pain histories lasting for more
than 6 months, or years, where no real etiology can be found, a referral
to a pain specialist and/or a neurologist or neurosurgeon can sometimes
be helpful in differentiating between chronic regional pain syndromes
type 1 and 2, and can provide useful information for surgeon and
patient alike.
Neuropathic pain complaints following hernia surgery can be subdivided
into either a chronic regional pain syndrome type 1 or type 2 ,
depending on (a) when the pain began after surgery: after a time lag
(type 1) or immediately (type 2), (b) whether or not the pain follows a
specific nerve distribution: no (type 1) or yes (type 2), and, finally, (c)
whether the pain is alleviated with local anesthetic blocks: no response
(type 1) or immediate but temporary response (type 2). It is believed that
neurectomy or removal of noxious material has a better chance of
resolving pain if type 2 exists while type 1 carries a worse prognosis.
Patients with type 1 often need referral to physicians specializing in coping
mechanisms and alternative therapeutic remedies. Nonetheless, it is
very important to ascertain whether the pain began before or after the
hernia repair, and if after the repair, how long after the repair.
Generally (and more practically), pain after an inguinal hernia repair
is caused by (a) the material inserted (mesh, tacks, or sutures), (b) an
inadequately reduced hernia, or (c) a missed lipoma or hernia.
Unfortunately, many recurrent hernias are actually just inadequately dissected
hernia fields the first time. The pain resulting from inserted mesh,
fixation tacks, technique, or sutures can be caused by direct irritation
from the material or by adjacent nerve damage. In an open repair, the
nerves that may be involved include the iliohypogastric, ilioinguinal,
and the genital branch of the genital femoral nerve. In a laparoscopic
repair, those at risk are the lateral femoral cutaneous nerve, the entire
genital femoral nerve and its distal branches, and—if tacking—the ilioinguinal
and iliohypogastric nerves. A careful history and physical
should be able to identify the affected nerve.