Clinical Concerns
Getting to the Bottom of
Chronic Post-Surgical Pain
Yoram Shir, MD
As presented at Thursday Evening Learning Series, McGill University, Montreal, Quebec (March 2006)
opulation surveys in the last two decades show
that chronic pain is a universal ailment, bringing
upon substantial suffering, disability and economic
loss. In Canada, almost one third of the adult population suffers from chronic pain.1 While multiple etiologies of chronic pain have been identified and characterized, chronic post-surgical pain (CPSP) is still a
neglected area (Table 1). Only recently has it become
clear that surgery is a major contributing factor in
more than 20% of chronic pain patients attending the
pain clinic.3 Moreover, in half of these patients, surgery was the sole factor initiating the chronic pain
condition. Unfortunately, there is only limited data on
CPSP in the general population. This fact is hard to
explain considering our advanced knowledge of pain
mechanisms, measurement and treatment modalities.
P
Larry’s Pain
• Larry, 52, is a heavy
smoker diagnosed with
lung cancer.
• He was seen at our Pain
Centre eight months
after undergoing a
thoracotomy and an
upper lobectomy of the left lung.
• Following the surgery he developed ongoing
severe pain in the surgical area. The pain was
accompanied by poor sleep and depression.
• The treating surgeon and oncologist could
not identify a reason for the severe pain.
• Initial treatment with non-opioid analgesics
and codeine preparations had no affect on
the pain.
What further treatment options are available?
See next page
What is the incidence of common
CPSP syndromes?
CPSP can probably develop after any surgery.
However, due to reasons that are not entirely clear,
certain surgeries carry higher risk for developing
CPSP (Table 2).4 It should be noted that the reported
incidence of most CPSP syndromes varies significantly among studies. For example, between 20% to
70% of women undergoing breast cancer surgery
report CPSP. This variation probably stems from multiple factors (e.g., retrospective vs. prospective studies, ethnic origin, etc.), some of which are not yet
known.
Table 1
Definition of
post-surgical pain2
• Pain developing after surgery.
• Pain persisting for at least two months.
• Other causes for pain have been excluded.
The Canadian Journal of Diagnosis / May 2006
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What are the contributing
factors for developing CPSP?
More on Larry
• More than 50% of patients undergoing a
thoracotomy are at risk for developing chronic
post-thoracotomy pain, similar to Larry.
• Treatment at our Pain Center involved
pharmacologic and invasive interventions,
including amitriptyline, 25 mg at bed time,
neurontin 1200 mg per day, strong opioids for a
limited period, scar infiltration with local
anesthetics, steroids and intercostal blocks.
• Six months after initiating treatment, Larry’s pain
decreased by 50%, his sleep and mood
improved and he was able to resume working
on a part-time basis.
Table 2
Reported incidence of common
chronic post-surgical pain
syndromes
• Following lumbar spine surgery
(failed back surgery syndrome):
15% to 30%
• Phantom pain following limb amputation:
30% to 80%
• Post thoracotomy:
22% to 67%
• Following breast cancer surgery:
20% to 72%
Can we decrease acute
post-surgical pain?
• Gallbladder surgery:
3% to 56%
• Inguinal hernia repair surgery:
0% to 54%
• Coronary artery bypass grafting:
56%
Dr. Shir is an Associate Professor of
Anesthesiology at McGill University in
Montreal and the Medical Director of
the Pain Centre at the McGill University
Health Centre, Montreal, Quebec.
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Multiple presurgical, intrasurgical and post-surgical contributors have been suggested as risk
factors for developing CPSP. It is important to
recognize the factors that may cause CPSP in
order to develop strategies to prevent and/or
better treat the problem. The major known contributing factors are listed in Table 3. Of these,
severe acute post-surgical pain is the most consistent risk factor for developing CPSP. It is
important to realize, however, that not all factors are relevant to each CPSP syndrome. For
example, younger age is associated with an
increased rate of CPSP in women undergoing
breast cancer surgery, but it does not predict an
increased risk of CPSP in patients undergoing
coronary artery bypass surgery.5 In contrast to
one’s expectations, the size of surgery is not
necessarily a predictor of increased levels of
CPSP. For example, a laparoscopic cholecystectomy is most likely not associated with lower
CPSP than open gallbladder surgery. Or, in
women with breast cancer, less invasive preservative surgery is associated with higher levels
of CPSP, compared to a formal mastectomy.6
Since increased levels of acute post-surgical pain
elevate the risk of CPSP, proper postoperative analgesia could be important not only for reducing
morbidity and the length of hospitalization, but
also to prevent transition into chronicity. Table 4
lists commonly used measures for decreasing
acute pain after surgery. Unfortunately, approximately 80% of patients still have pain after surgery,
86% of which report at least moderate pain.7
The Canadian Journal of Diagnosis / May 2006
CPSP
What are the current treatment
modalities for CPSP?
I am not familiar with specific recommendations for treating CPSP. Therefore, these pain
syndromes should probably be treated like
other chronic pain conditions; treatment should
depend on:
• the type of pain
(e.g., visceral, neuropathic),
• pain levels,
• previous treatment modalities and
• other medical conditions (Table 5).
Currently, there is practcally no data on the
long-term prognosis of these patients, or on the
success rate of their treatment.
Table 3
Possible contributing factors for
developing chronic post-surgical
pain
• Younger age
• Increased preoperative pain
• High preoperative depression and anxiety
• Surgical technique
• Severe acute post-surgical pain
Table 4
Commonly used analgesic
measures for acute post-surgical
pain
• Medications: non-opioids, opioids
Can we decrease the incidence
of CPSP in the future?
It is a well accepted fact that efforts aimed at
preventing CPSP have a better chance of
decreasing the incidentce of CPSP than treating
it once it has already developed. Prevention can
be achieved in two ways:
1. Identifying predictors for CPSP
At present, we cannot predict which patients
will develop severe pain after experiencing
trauma or undergoing surgery. It is possible,
however, that preoperative differences in pain
sensitivity could predict post-surgical pain.
Indeed, preliminary psychophysical studies
indicate that increased preoperative pain levels,
in response to painful pressure, (i.e., hot and
cold stimuli) were significantly associated with
increased post-surgical pain.8 It is possible
then, that normal responses, prior to injury,
could predict the intensity of acute and chronic
pain after surgery. The ability to identify
patients at higher risk for developing CPSP
• Wound infiltration with local anesthetics
• Peripheral nerve blocks
• IV patient-controlled analgesia with opioids
• Epidural analgesia
Table 5
Treatment of chronic postsurgical pain
• Pharmacotherapy:
- Non-opioid analgesics
- Adjuvant medications
(e.g., antidepressants, antiepileptics)
- Opioids
• Physical modalities:
- Physiotherapy and rehabilitation
- TENS
• Invasive interventions:
- Nerve blocks
- Ablative procedures
• Psychological and behavioral approach
TENS: Trans-cutaneous electrical nerve stimulation
The Canadian Journal of Diagnosis / May 2006
85
before surgery will hopefully enable the early
use of more aggressive analgesic measures.
2. Developing preventive analgesic
measures
Although still controversial, there are indications that aggressive analgesic interventions
provided before surgery could prevent the
alterations in sensory processing. The alterations in sensory processing amplify postinjury pain and lead to chronicity. Presurgical
interventions (e.g., continuous use of epidural
anesthesia and analgesia) could decrease the
incidence of chronic post-surgical pain.9 Dx
References
1. Moulin D, Clarke A, Speechley M, et al: Chronic pain in Canada
prevalence, treatment, impact and the role of opioid analgesia.
Pain Res Manag 2002; 7(4):179-84.
2. Macrae W: Chronic pain after surgery. Br J Anaesth 2001;
87(1):88-98.
3. Crombie I, Davies H, Macrae W: Cut and thrust: Antecedent surgery and trauma among patients attending a chronic pain clinic.
Pain 1998; 76(1-2):167-71.
4. Perkins F, Kehlet H: Chronic pain as an outcome of surgery. Anesth
2000; 93(4):1123-33.
5. Macdonald L, Bruce J, Scott N, et al: Long-term follow-up of breast
cancer survivors with post-mastectomy pain syndrome. Br J Cancer
2005; 92(2):225-30.
6. Tasmuth T, von Smitten K, Kalso E: Pain and other symptoms during
the first year after radical and conservative surgery for breast cancer.
Br J Cancer 1996; 74(12):2024-31.
7. Apfelbaum J, Chen C, Mehta S, et al: Postoperative pain experience:
results from a national survey suggest postoperative pain continues
to be undermanaged. Anesth Analg 2003; 97(2):534-40.
8. Granot M, Lowenstein L, Yarnitsky D, et al: Postcesarean section pain
prediction by preoperative experimental pain assessment. Anesth
2003; 98(6):1422-6.
9. Obata H, Sarto S, Fujita N et al: Epidural block with mepivacaine
before surgery reduces long-term post-thoracotomy pain. Can J
Anesth 1999; 46(12):1127-32.
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Take-home
message
• Chronic post surgical pain is an under
recognized, prevalent and a debilitating
public health problem.
• Current clinical practices are not sufficient
to prevent the development of chronic
post-surgical pain.
• Preventive measures and early aggressive
interventions should be developed.
• The primary physician should have a central role in early detection and treatment of
this problem.
The Canadian Journal of Diagnosis / May 2006