Page 151 Guide to Pain Management in Low-Resource Settings

Abdominal Cancer, Constipation, and Anorexia 139

as pain felt in the spinal column, due to the distribution What are the expected success rates
of intercostal or other spinal nerves. with “simple” analgesia methods?

Why it is so diffi cult for the patient Pain management in patients with gastrointestinal can-

with visceral pain to identify cer is fairly easy. From the literature, we know that in
more than 90% of patients, the pain may be controlled
exactly the spot that hurts? with simple pain management algorithms. Observa-
tional studies from palliative care institutions, such
Visceral aff erent fi bers (pain-conducting C fi bers) con-
as the Nairobi Hospice, Kenya, report an almost 100%
verge on the spinal level at the dorsal horn. Th erefore,
success rate with a simple pain algorithm. As with all
discrimination of pain and exact localization of the
cancer pain, the pain management protocol follows
source of pain is impossible for the patient. A patient
the WHO recommendations, and is based on a com-
with pancreatic cancer would never tell the doctor that
bination of opioids and nonopioid analgesics, such as
his pancreas hurts, but instead will report “pain in the
paracetamol, dipyrone, or nonsteroidal antiinfl amma-
upper part of the belly” radiating around to his back in
tory drugs (NSAIDs). Coanalgesics and invasive therapy
a bandlike fashion. Th is radiation of pain is called “re-
options are rarely indicated (see other chapters on gen-
ferred pain.”
eral rules for cancer pain management and on opioids).
If fl uoroscopy is available, along with adequately trained
Why is it interesting to know how clinicians, neurolysis of the celiac plexus may be used to
the nociceptive fi bers from the reduce the amount of opioids and augment pain control
visceral organs travel? in hepatic and pancreatic cancer.

Th e nociceptive pain conducting aff erent nerve fi bers
of some of the visceral organs meet sympathetic eff er- Why are some people reluctant to
ent fi bers before reaching the spinal cord in knots called use morphine or other opioids in
nerve plexuses. From here, the pain-conducting fi bers patients with gastrointestinal cancer?
continue via the preganglionic splanchnic nerves to the
From early studies, we know that one of the undesired
spinal cord (T5–T12). Th is situation allows an interest-
eff ects of morphine is the induction of spasticity at the
ing therapeutic option: interruption of the nociceptive
sphincter of Oddi and bile duct. Th is opioid side eff ect
pathway with a neurolytic block at the site of the celiac
is mediated through the cholinergic action of opioids
plexus. Th is is one of the few remaining “neurodestruc-
as well as through direct interaction of the opioids with
tive” therapeutic options still considered useful today.
mu-opioid receptors. Consequently, in the past there
Nerve destruction at other locations has been shown to
was some reluctance to use morphine. Instead pethidine
cause more disadvantages than benefi ts to the patient,
(meperidine) was preferred. Recent studies have not
such as anesthesia dolorosa (pain in the location of
confi rmed these fi ndings, and so morphine can be used
nerve deaff erentation).
without reservations.
How does the patient typically
describe his intra-abdominal pain? Where and how should
neurodestructive techniques be
Generally, pain of the intra-abdominal organs originates used?
from the stimulation of terminal nerve endings, and is
referred to as visceral-somatic pain, as opposed to pain For upper abdominal cancer, the target structure would
from nerve lesions, which is called neuropathic pain. Th e be the celiac plexus. For colon and pelvic organ can-
pain characteristic most often reported by the patient is cers, the target is the myenteric plexus, and for bladder
that it is not well localized. Patients typically describe the and rectosigmoid cancers, the hypogastric plexus is the
pain as generally “dull” or “pressing,” but sometimes “col- target. Usually these structures are easy to identify us-
icky.” Pain intensity is assessed as in all other pain etiolo- ing landmarks and fl uoroscopy. If available, a comput-
gies, with the visual or numeric analogue scale. ed tomography (CT) scan would be the gold standard