One of the potential adverse outcomes following surgery is the development of chronic pain. Although this occurs with sufficient frequency to represent a real problem following various surgical procedures, it is rarely anticipated by patients preparing for surgery. The typical expectation is akin to that of bringing an automobile in for repair in which the problem will be fixed and life will resume without persistent complication. The authors of this review article specifically reviewed population data reflecting the incidence of chronic postoperative pain or predictors (medical, physiologic, and psychologic) of chronic pain. They looked at five groups of surgeries, including limb amputations, breast surgery, gallbladder surgery, lung surgery and inguinal hernia surgery.

The authors performed a computerized search of the medical literature using the OVID search engine, looking at articles from 1966 through 1998. The authors only examined persistent pain problems which had persisted at least 12 weeks or more after surgery and in which the method section of the chosen article indicated a systematic collection of long-term pain information for patients.

Limb amputation. Phantom limb pain is common following extremity amputation. The reported incidence of phantom limb pain varies from 30-81%. The incidence of stump pain exceeds 60%. Documented predictors of this pain include pre-amputation pain and persistent stump pain (acute and chronic). No conclusive studies have evaluated the effect of acute or subacute stump pain control on long-term stump pain or on long-term phantom limb pain. In addition, no psychologic studies have evaluated patients before amputation to look for predictors of chronic pain.

Thoracotomy. The incidence of long-term pain following thoracotomy or a post-thoracotomy pain syndrome may have an incidence of greater than 50%.

The development of a post-thoracotomy pain syndrome is common. Predictors for this syndrome include the extent of acute postoperative pain and intercostal nerve dysfunction. One prospective randomized controlled study found that the combination of intraoperative plus postoperative thoracic epidural analgesia decreased the incidence of post-thoracotomy pain syndrome at the six month follow-up.

Breast Surgery. Women undergoing breast surgery experience chest wall, breast or scar pain (ranging from 11-57%), phantom breast (13-24%), and arm and shoulder pain (12-51%).

The incidence of pain in one or more of these sites is close to 50% one year following breast surgery for cancer. Chronic pain is a common finding following breast surgery. The major predictive factors are the extent of acute postoperative pain, the presence of pain before surgery, the type of surgery, intercostobrachial nerve damage, adjuvant radiation therapy, and possibly preoperative anxiety or depression.

Gallbladder Surgery. Chronic abdominal pain following cholecystectomy is common. This ranges in incidence from 3-56%, but is less frequent than the preoperative incidence of pain in this setting, which ranges from 83-100%. The post-cholecystectomy syndrome has a number of components in addition to abdominal pain and may not have a single underlying etiology. Pathogenic factors may include postoperative somatic incisional pain, pain caused by postoperative sphincter of Oddi dysfunction, pain caused by preoperatively undiagnosed disease other than gallbladder stone, pain caused by a bile duct stone, and other preoperative factors that predispose the patient to an unfavorable outcome.

Chronic symptoms are common after cholecystectomy as is chronic abdominal pain. Predictive factors include psychologic vulnerability, long-standing preoperative symptoms (including pain), and pain at six weeks following surgery. Prospective studies looking at post-cholecystectomy syndrome have not separated scar pain and neuropathic pain from other causes of chronic visceral pain and symptoms.

Inguinal Hernia Surgery. A number of studies have evaluated chronic pain following groin surgery, with the reported incidence of chronic pain varying from 0-37%. The overall incidence from these studies is 11.5%.

Chronic pain following groin hernia surgery is not rare, but it appears to be less common than chronic pain after the other surgeries cited above. Because hernia surgery is quite common, a large number of individuals are affected by this type of chronic pain. Nerve dysfunction has been shown to be a factor as has the intensity of early postoperative pain. The role of acute pain therapy on the incidence of chronic pain in this setting is unknown.

Patient satisfaction with surgical results in general is reported to be quite high. Despite this, the studies contained in this review article demonstrate that chronic pain is common following this group of surgeries. The authors identify the number of risk factors for prolonged pain after surgery, which were divided into three categories:

1. preoperative factors
2. intraoperative factors
3. postoperative factors

They identify preoperative pain as a predictor of chronic pain for post-amputation pain, phantom breast pain, and non-colicky abdominal pain and symptoms after cholecystectomy. For each of these surgeries, the characteristic of the preoperative pain that predicted chronic pain tended to be continuous pain of one month or more in duration. Psychologic vulnerability is a risk factor for persistent pain after cholecystectomy, but has not been evaluated in the other surgeries reviewed.

Nerve damage is an intraoperative factor that contributes to chronic postoperative pain.

The most striking predictive postoperative factor is the severity of acute postoperative pain after breast surgery, thoracic surgery and hernia repair. Postoperative adjuvant radiation therapy increases the risk of chronic pain after breast surgery and neurotoxic chemotherapy increases the risk for phantom limb pain. The role of acute pain in the development of chronic pain has been debated. The role of persistent pain following surgery producing sensitization is still open for debate. It is theorized that prevention may be possible if sensitization can be blocked. This has been demonstrated in one study looking at thoracotomy patients in which intraoperative plus postoperative epidural analgesia provided decreased postoperative pain. However, other clinical studies of preemptive analgesia and their role in the development of chronic pain syndromes are far from consistent.

The authors concluded by saying that chronic pain is common after amputation, inguinal hernia surgery, breast surgery, gallbladder surgery and lung surgery. They suggested that future studies should characterize the factors of importance in the transition from acute to chronic pain. The development of such knowledge may result in designing more effective and more rational early interventions. They hypothesized that in some patients the type of nerve injury may explain both the increase in acute pain and chronic pain, but the extent of pain will be modified by other factors, particularly psychologic and physiologic factors that heighten pain sensitivity.

Drs. Perkins and Kehlet have provided a valuable service in writing this review that discusses the incidence of chronic pain following five common types of surgery. It is only if we are aware of the potential for these chronic pain syndromes that we can adequately inform patients preoperatively about their risks, and begin to ask questions and develop studies to look at the factors that contribute to the development of these postoperative pain syndromes. It is only by addressing all three areas that we will be able to decrease the incidence and severity of these chronic pain problems in patients undergoing common surgeries. This is a valuable review that should be read both by anesthesiologists as well as the surgeons performing these various surgeries.