Chapter 35 Chronic Pain after Surgery Flashcards
KEY POINTS 1. Chronic pain after surgery is common. 2. Risk factors include patients with preexisting pain, psychosocial factors, age, gender, and possibly genetic susceptibility. 3. CPSP can be prevented using good surgical technique (avoiding nerve damage and using minimally invasive techniques) and aggressive multimodal analgesia starting immediately prior to surgery. 4. Future strategies should include more consistent use of multimodal analgesia across surgical populations and screenin
chronic pain after surgery definition
The pain should have developed after a surgical
procedure.
2. The pain should be of at least 2 months duration.
3. Other causes of the pain should be excluded, such as
recurrence of malignancy or infection.
4. The possibility that the pain is continuing from a
preexisting problem should be explored and exclusion
attempted.
Factors Associated with Development of Chronic Pain after Surgery
Preoperative Factors
Moderate–severe pain of >1 mo duration
Repeat surgery
Psychological factors
Factors Associated with Development of Chronic Pain after Surgery
Intraoperative Factors
Surgical approach with risk of nerve injury
Nonlaparoscopic technique
Surgery in low-volume center
Factors Associated with Development of Chronic Pain after Surgery
Postoperative Factors
Moderate–severe acute pain
Neurotoxic chemotherapy
Radiation therapy to site
A consistent factor associated with development of acute
and CPSP across many types of surgery is the presence
of preoperative pain. The
presence of preoperative pain is a risk factor for the development of early acute postoperative pain, pain in the
days, weeks, and months following surgery.
independent predictors of severe pain
preoperative pain, female gender, younger age,
incision size, and type of surgery
A very consistent factor in the
development of CPSP is the presence of
either severe preoperative pain, postoperative pain, or both.
Several factors may explain the consistent relationship
of preoperative and severe acute postoperative pain predicting
CPSP, including the following:
- Preoperative opioid tolerance leading to underestimation and underdosing of postoperative opioid analgesics.
- Intraoperative nerve damage and the associated
CNS changes such a central sensitization and “wind-up.” - Sensitization of pain nociceptors in the surgical
field. - Postoperative ectopic activity in injured primary
afferents and collateral sprouting from intact nociceptive Ad-afferents neighboring the area supplied
by injured afferents. - Central sensitization induced by the surgery and
maintained by further input from the surgical site
during the healing process.
Several factors may explain the consistent relationship
of preoperative and severe acute postoperative pain predicting
CPSP,7 including the following:
- Structural changes in the CNS (plasticity) induced by nociceptive inputs with
consequent reduction in normal inhibitory control
systems leading to “centralization” of pain
and development of pain memories. - Heretofore unidentified pain genes that may confer
increased risk of developing both severe acute
and chronic postsurgical pain. - Psychological and emotional factors such as emotional numbing and catastrophizing
- Social and environmental factors such as solicitous
responding from significant others and social support - Response bias over time—that is, some individuals
have a tendency to report more pain than other
individuals. - Publication bias in which findings of a significant
relationship between pain before and after surgery
are published, whereas negative findings are rejected
and do not get published.
psychosocial predictors of chronic postsurgical
pain
increased preoperative
anxiety, an introverted personality, less catastrophizing, social support and solicitous responding in the week after amputation, higher emotional numbing scores at 6 and 12 months, fear of surgery, and “psychic vulnerability
Pain catastrophizing
relates to unrealistic beliefs that
the current situation will lead to the worst possible pain
outcome.
Solicitous responding
refers to the behaviors on the
part of spouses or significant others who unwittingly
reinforce patients’ negative behaviors and thereby increase
their frequency of occurrence
Three main surgical factors have a possible influence on
the incidence of CPSP
Experience of the surgeon
Avoidance of intraoperative nerve injury.
Use of minimally invasive surgical techniques where possible
Many CPSP syndromes occur following
surgery around significant nerve structures Examples
pain after inguinal hernia repair (ilioinguinal and iliohypogastric nerves), axillary dissection (intercostobrachial nerve), and post-thoracotomy pain (intercostal nerves).
When a nerve is injured
it emits a long-lasting, high frequency burst of activity. This activity is transmitted to the central nervous system where the massive excitatory
stimulus activates postsynaptic NMDA receptors, leading to
excitotoxic destruction of inhibitory interneurons,18 disinhibition
of pain pathways, and increased postoperative pain
