Chronic Pain After Surgery
The experience of pain is more than the detection of noxious stimuli transmitted to the central nervous system. Pain perception is influenced by mood, memories, expectation and social environment and so psychosocial factors should be considered alongside pain assessment and management.
The fear-avoidance model, thought to be important in the initiation and maintenance of chronic pain, demonstrates the importance of psychological factors in chronic pain (figure 2). In this model, a person believes that pain signals danger or harm. Fear of pain leads to avoidance of activities that may induce or exacerbate pain. Fear-avoidance behaviour may ultimately lead to disuse and disability, and a fear of pain has actually been found to better predict disability than the pain itself. Individuals who 'catastrophise' are more likely to enter into this cycle of fear-avoidance behaviour. Catastrophising can be described as an almost immediate habitual negative appraisal of a situation. A person might believe, for example, that if they bend their back then it will break and they will become wheelchair users. The relationship between the experience of pain and behavioural activity is mediated by expectation of pain and the anticipation of catastrophic consequences if certain activities are carried out. Anticipation of pain should be a helpful, adaptive response leading to modification of behaviour to avoid pain. However, it can become maladaptive in the chronic pain setting. Neuroimaging studies examining how anticipation and anxiety can heighten pain perception have revealed certain regions to be important in amplifying the pain experience. These regions include the entorhinal complex, amygdalae, anterior insular and prefrontal cortices.
(Enlarge Image)
Figure 2.
The fear-avoidance model (figure reproduced with permission of International Association for the Study of Pain).
Psychological factors play a significant role in both acute and chronic back pain, and in the transition from acute to chronic pain. Psychosocial factors have in fact been found to have a greater impact than biomedical or biomechanical factors on back pain disability. Psychological factors are also known to influence acute postoperative pain, for example, Katz et al found a correlation between preoperative anxiety and acute postoperative pain in women undergoing breast cancer surgery. There is less in the literature concerning the role of psychosocial factors in pain persisting after surgery, although psychological vulnerability (eg, catastrophising), anxiety, depression, neuroticism and late return to work have all been found to be risk factors. Patients with a fear of the long-term consequences of surgery are also at increased risk of long-term pain and poor recovery.
Making sense of pain, what it may mean and what it does not mean are essential for effective coping. Pre-emptive cognitive and behavioural interventions decrease anxiety before and after surgery, reduce postoperative pain intensity and analgesic use. A study by Egbert et al nearly 50 years ago demonstrated a reduction in morphine requirements and length of stay when patients were provided with preoperative information about likely postoperative treatments and discomfort and instruction on relaxation techniques. When patients are given information about what they should expect to feel, in addition to procedural information, they experience less pain and distress compared with either type of information given alone. Relating this back to the fear-avoidance model we can see that information can provide reassurance that the sensations experienced after a procedure are normal and non-threatening. For example, following a total knee replacement, patients are encouraged to mobilise within hours of surgery. This may be uncomfortable, but it is important that patients are reassured that pain does not equal damage, that it is normal to experience some discomfort and it does not mean that they are jeopardising their operation or that something is wrong.
Educating patients and their carers about pain encourages a more positive attitude to pain relief and where possible we should try to involve patients in their pain management strategy. Through active involvement patients develop a greater sense of self-efficacy regarding treatment and disease-related behaviours and may be more likely to follow through on management decisions reached. Patients who respond passively to pain show greater distress and disability compared with those who attempt to solve the problem. Taking some control over the cause of pain or the method of analgesia has a beneficial effect.
Social relationships can also influence pain reporting and disability. A study of chronic back pain patients found that when a partner is present who is attentive and likely to help them to avoid activities that may exacerbate pain then a patient is likely to report more pain and underperform on tasks. The expressions of pain are reinforced by the partner who acts to alleviate the patient's behavioural activity, and this is reflected in the increased level of pain.
Managing expectation is recognised as an important component of enhanced recovery programmes. Carefully presented information from surgeons, anaesthetists and nurses about the surgical procedure, anticipated sensory experiences, analgesic treatment and recovery period is expected to reduce anxiety and promote recovery. By addressing these issues in the perioperative period, it may be that we can also reduce the progression to persistent pain and disability in those at risk.
Psychosocial Factors
The experience of pain is more than the detection of noxious stimuli transmitted to the central nervous system. Pain perception is influenced by mood, memories, expectation and social environment and so psychosocial factors should be considered alongside pain assessment and management.
The fear-avoidance model, thought to be important in the initiation and maintenance of chronic pain, demonstrates the importance of psychological factors in chronic pain (figure 2). In this model, a person believes that pain signals danger or harm. Fear of pain leads to avoidance of activities that may induce or exacerbate pain. Fear-avoidance behaviour may ultimately lead to disuse and disability, and a fear of pain has actually been found to better predict disability than the pain itself. Individuals who 'catastrophise' are more likely to enter into this cycle of fear-avoidance behaviour. Catastrophising can be described as an almost immediate habitual negative appraisal of a situation. A person might believe, for example, that if they bend their back then it will break and they will become wheelchair users. The relationship between the experience of pain and behavioural activity is mediated by expectation of pain and the anticipation of catastrophic consequences if certain activities are carried out. Anticipation of pain should be a helpful, adaptive response leading to modification of behaviour to avoid pain. However, it can become maladaptive in the chronic pain setting. Neuroimaging studies examining how anticipation and anxiety can heighten pain perception have revealed certain regions to be important in amplifying the pain experience. These regions include the entorhinal complex, amygdalae, anterior insular and prefrontal cortices.
(Enlarge Image)
Figure 2.
The fear-avoidance model (figure reproduced with permission of International Association for the Study of Pain).
Psychological factors play a significant role in both acute and chronic back pain, and in the transition from acute to chronic pain. Psychosocial factors have in fact been found to have a greater impact than biomedical or biomechanical factors on back pain disability. Psychological factors are also known to influence acute postoperative pain, for example, Katz et al found a correlation between preoperative anxiety and acute postoperative pain in women undergoing breast cancer surgery. There is less in the literature concerning the role of psychosocial factors in pain persisting after surgery, although psychological vulnerability (eg, catastrophising), anxiety, depression, neuroticism and late return to work have all been found to be risk factors. Patients with a fear of the long-term consequences of surgery are also at increased risk of long-term pain and poor recovery.
Making sense of pain, what it may mean and what it does not mean are essential for effective coping. Pre-emptive cognitive and behavioural interventions decrease anxiety before and after surgery, reduce postoperative pain intensity and analgesic use. A study by Egbert et al nearly 50 years ago demonstrated a reduction in morphine requirements and length of stay when patients were provided with preoperative information about likely postoperative treatments and discomfort and instruction on relaxation techniques. When patients are given information about what they should expect to feel, in addition to procedural information, they experience less pain and distress compared with either type of information given alone. Relating this back to the fear-avoidance model we can see that information can provide reassurance that the sensations experienced after a procedure are normal and non-threatening. For example, following a total knee replacement, patients are encouraged to mobilise within hours of surgery. This may be uncomfortable, but it is important that patients are reassured that pain does not equal damage, that it is normal to experience some discomfort and it does not mean that they are jeopardising their operation or that something is wrong.
Educating patients and their carers about pain encourages a more positive attitude to pain relief and where possible we should try to involve patients in their pain management strategy. Through active involvement patients develop a greater sense of self-efficacy regarding treatment and disease-related behaviours and may be more likely to follow through on management decisions reached. Patients who respond passively to pain show greater distress and disability compared with those who attempt to solve the problem. Taking some control over the cause of pain or the method of analgesia has a beneficial effect.
Social relationships can also influence pain reporting and disability. A study of chronic back pain patients found that when a partner is present who is attentive and likely to help them to avoid activities that may exacerbate pain then a patient is likely to report more pain and underperform on tasks. The expressions of pain are reinforced by the partner who acts to alleviate the patient's behavioural activity, and this is reflected in the increased level of pain.
Managing expectation is recognised as an important component of enhanced recovery programmes. Carefully presented information from surgeons, anaesthetists and nurses about the surgical procedure, anticipated sensory experiences, analgesic treatment and recovery period is expected to reduce anxiety and promote recovery. By addressing these issues in the perioperative period, it may be that we can also reduce the progression to persistent pain and disability in those at risk.