Resources for healthcare professionals


This is a list of some medical terms that you may come across on this site, in books or during discussions with healthcare professionals.

The development of an inappropriate or maladaptive way of acting and coping with one`s own state of health, in spite of the fact that a clinician has offered a reasonable explanation for the nature of the condition and appropriate course of management. It is particularly associated with the symptom of persistent low back pain.

Abnormal illness behaviour is sometimes taken to be synonymous with malingering. This is only the case when motivation is predominantly conscious rather than unconscious.

A technique involving the placement of fine needles at various specific points throughout the body. It has been reported to be beneficial in headache and backache in addition to other soft tissue pain syndromes.

Over the past decade, increasing attention has been paid to the effective management of pain after surgery. This culminated in a government Green Paper and a recommendation that all hospitals develop a multi-disciplinary acute pain service.

The pain service team includes a physician trained in pain management (usually an anaesthetist), a nurse and other healthcare professionals, such as a physiotherapist and psychologist, where appropriate.

The purpose of an acute pain service is to reduce the severity and frequency of postoperative or post-traumatic pain. It has been demonstrated that the most important step in reducing postoperative pain is to include pain scoring as a routine measure, much in the same way as pulse, BP and temperature are measured.

An acute pain service also has an important role in educating patients and clinical staff about the options available to treat and relieve pain.

Myelinated nociceptor fibres which have the capacity to respond to intense heat, cold, mechanical and chemical stimuli. Activation of A δ fibres is associated with a sharp, intense, stabbing sensation of pain and they are thought to be responsible for conducting the first pain sensation, since they conduct at 5–30 metres per second.

Drugs whose primary use is not for managing pain, but in certain conditions they have analgesic properties and often will enhance the response to conventional analgesics. Examples include antidepressant and anticonvulsant drugs.

Pain produced by a stimulus which is normally not painful. For example, gently stroking an area may produce pain in people with complex regional pain syndrome (CRPS). Although different from referred pain it can occur in areas other than the one stimulated.

Allodynia is associated with abnormalities in central processing, usually caused by injury to part of the nervous system. This physical sign is commonly demonstrated in neuropathic pain states and is a particular feature of postherpetic neuralgia.

Pain occurring in an anaesthetic area, that is one where sensation is not normally perceived. Anaesthesia dolorosa is one of the complications of treatment for trigeminal neuralgia.

Drugs that are primarily used for the treatment of epilepsy, but which have also been used for many years to reduce the severity of pain in neuropathic pain states.

Carbamazepine is commonly used in the treatment of trigeminal neuralgia. Some of the newer anticonvulsant agents, for example gabapentin, have also been shown to be beneficial in the treatment of neuropathic pain states. The use of these medications is often limited by the development of side-effects, particularly sedation and drowsiness.

Tricyclic antidepressants (TCAs) have been used for many years in the treatment of low back pain. These drugs are particularly useful at doses lower than those used to treat depression.

Described by the patient as a continuous pain, often having a burning or aching quality without pain-free intervals. There are no triggering factors and pain may be unilateral or bilateral and extend over several dermatomes.

The term was originally used to distinguish it from the pain of trigeminal neuralgia. On examination there is rarely any sensory loss and all investigations are normal. This syndrome is often associated with significant behavioural changes and sometimes responds to behavioural therapy and TCAs.

The simultaneous use of drugs from different pharmacological classes to produce a greater degree of analgesia than can be achieved by using the drugs individually.

This technique is commonly used in the treatment of acute postoperative pain. In this situation, the combination of a local anaesthetic agent, an opioid and an anti-inflammatory drug can help to reduce postoperative pain with fewer side-effects than using the individual drugs at a higher dosage.

A theoretical model that relies on the premise that no single dimension is adequate to understand chronic pain.

It suggests that to understand chronic pain it is necessary to consider the interaction of biological, psychological and social factors. The model proposes that there is an interaction between the perception and behavioural response of an individual to a painful condition and the environment and social context in which that person lives.

Essentially, the model recognises that pain is rarely a phenomenon that occurs in isolation. Successful management requires attention to all components of the model.

Unmyelinated nociceptor neurones, which conduct at a velocity of less than two metres per second and are associated with a prolonged burning sensation and dull aching pain. They are responsible for the secondary pain sensation that follows brief intense heat stimulation to the skin. The term ‘slow pain’ is often used to describe the pain caused by activation of C fibres.

Pain caused by lesions or dysfunction of the CNS, be it within the spinal cord or brain.

The most common descriptions of this pain include burning, aching, darting, piercing, pricking, lacerating and pressing.

Central pain can occur after cerebral vascular accidents either due to an infarct or haemorrhage. It is also seen in association with traumatic spinal cord and brain injury and MS.

Treatment of central pain is notoriously difficult and there is no universally effective treatment. A range of pharmacological agents have been tried with varying degrees of success, including antidepressants, anticonvulsants and antiarrhythmics. Opioids have also been used and combination therapy may be beneficial.

Pain associated with either a demonstrable progressive pathological process such as rheumatoid arthritis or malignancy or pain that is present long after the immediate effects of an injury have subsided and persists beyond the healing time.

Pain can be described as chronic when it exists for longer than three to six months. Chronic pain is almost invariably accompanied by a significant behavioural response and varying degrees of disability.

See adjuvant analgesics.

The coeliac plexus extends from the front of the body of the 12th thoracic vertebra to the front of the first lumbar vertebra.

The application of a neurolytic solution, either alcohol or phenol, to the coeliac plexus after a diagnostic block with local anaesthetic can be used to successfully treat the pain from upper abdominal tumours, particularly visceral pain due to pancreatic cancer. The injection should be performed under X-ray control, using either conventional fluoroscopy or CT scanning.

A variety of approaches have been suggested and opinion is divided as to whether or not a diagnostic block should be performed before injecting the neurolytic agent in order to evaluate the potential effect of this permanent block.

Complications include hypotension due to vasodilatation of the splanchnic bed, subarachnoid injection and neurological sequelae in 1 per cent of patients.

An approach to the management of chronic pain directed towards considering how the person relates to their pain and addressing the patient’s understanding of their painful condition. The treatment focuses on understanding the person’s thoughts about their condition and modifying any abnormal beliefs and misconceptions.

Refers to two conditions previously known as reflex sympathetic dystrophy and causalgia. CRPS encompasses a range of painful conditions, which usually occur after injury. It is usually confined to the extremities, although there are increasing reports in cases of low back pain.

It is typical of the condition that the magnitude and duration of symptoms appear to be out of proportion to the event that caused the injury. There is a wide range of clinical appearances, ranging from mild swelling together with trophic changes in the skin, to gross swelling and deformity necessitating amputation.

Patients often exhibit considerable fear avoidance behaviour and avoid those activities they know will increase their pain. There are often considerable secondary effects due to disuse of the affected limb.

Treatment is directed to encourage early mobilisation when the condition is diagnosed and to facilitate active mobilisation with a variety of measures, including local anaesthetic nerve blocks, the use of anticonvulsants and other co-analgesics. Even dorsal column stimulation may be beneficial. CRPS is subdivided into two types.

Diagnosis of type 1 CRPS (reflex sympathetic dystrophy):

  • There should be a history of an initiating noxious event, for example trauma.
  • There must be evidence of spontaneous pain, allodynia or hyperalgesia. The pain that develops is not limited to the territory of a single peripheral nerve and is out of proportion to the initiating stimulus.
  • There has been evidence of abnormal sudomotor activity, oedema or alterations in the skin blood flow in the area of the pain since the initiating event.
  • Diagnosis is excluded by the presence of conditions that would otherwise account for the degree of pain.

Diagnosis of type 2 CRPS (causalgia):

  • The syndrome develops after a specific nerve injury. Spontaneous pain, allodynia or hyperalgesia occurs, but is not necessarily limited to the territory of the injured nerve.
  • There has been evidence of altered skin blood flow, abnormal sudomotor activity or oedema in the region where the pain is experienced.
  • The existence of conditions that could otherwise cause the degree of pain being experienced by the patient have been excluded.

Pain due to a lesion or dysfunction in the nervous system resulting from loss of sensory input into the CNS. This can occur with peripheral nerve lesions, such as brachial plexus avulsion, or in association with pathology in the CNS.

See spinal cord stimulation.

An uncommon complication of epidural analgesia. With early diagnosis and treatment a favourable outcome should be obtained. It occurs more commonly in the absence of epidural analgesia and is associated with type-1 diabetes, cancer, degenerative disease of the spine and spinal surgery.

The incidence of epidural abscess associated with perioperative epidural analgesia is less than 0.01 per cent. Four clinical phases are described in the development of an epidural abscess. Initially there is back pain occurring within 24 hours of the abscess development, followed by root pain, fever, sphincter and muscular weakness and finally paralysis.

With increasing use of perioperative epidural analgesia a high degree of vigilance is recommended to avoid this complication.

The infusion of local anaesthetic drugs, with or without the addition of opioids, into the epidural space. It is useful in reducing acute postsurgical pain, acute pain from causes such as labour and trauma and sometimes in the management of cancer-related pain.

By combining opioids and local anaesthetic agents such as bupivacaine, it is possible to achieve good levels of pain relief without producing motor blockade. The use of dilute solutions of local anaesthetic enables patients to be ambulatory with reduced pain levels.

Experience shows that patients can be safely managed with continuous infusions of local anaesthetic and opioids in the epidural space on postoperative wards providing that rigid guidelines are in place. Routine monitoring includes sedation scores, pain scores and respiratory rate.

Complications include hypotension, dural puncture headache, pruritus and urinary retention. Some evidence suggests that continuous use may reduce postoperative hospital stay.

Injections of steroids into the epidural space to treat radicular pain have been used for four decades; they are mainly indicated for conditions of nerve root irritation and inflammation. Despite the length of time for which this treatment has been used, there are very few good prospective, randomised, double-blind, placebo-controlled trials in the literature.

Factors relating to a favourable outcome include pain duration of less than six months, a primary diagnosis of radicular pain and good educational background. Poor outcome is associated with a history of constant pain, loss of employment due to pain and frequent sleep disturbance.

The most common combination injected is a weak local anaesthetic solution such as bupivacaine and triamcinolone. A variation on this is to use saline rather than a local anaesthetic.

It is important to thoroughly evaluate and counsel the patient before the procedure. They should be advised that steroids are not licensed for the epidural route. An explanation should be given as to what this means.

A common clinical condition in which reproducible tenderness is elicited in specified areas of the body associated with widespread pain and symptoms of stiffness, fatigue, altered sleep pattern and depression of mood. It is most commonly seen in females aged between 20 and 50. Typically there is a history of widespread pain situated above and below the diaphragm on both sides of the body, lasting for longer than three months. In addition there should be pain in 11 out of 18 tender points on palpation. Palpation should be performed with a force of 4kg.

Patients should be reassured that they have a benign condition. The aim of treatment is to help them cope with their symptoms more effectively. Interventions shown to be of benefit include the use of low-dose TCAs and participation in a pain management programme.

Fibromyalgia is also associated with irritable bowel syndrome, migraine, Raynaud’s disease, non-dermatomal paraesthesia and considerable disability.

As proposed by Melzack and Wall in 1965. They suggested that it was possible to modulate noxious impulses at spinal cord level.

Stimulation of large diameter A β fibres, which are non-nociceptive, inhibits the response to painful stimuli of wide dynamic range neurones in the dorsal horn of the spinal cord.

Descending inputs are also thought to modulate activity in the dorsal horn, which helps to explain how cognitive and emotional factors influence nociceptive processing.

Also known as IV regional analgesia, this technique was first described by Hannington-Kiff in 1974 and involves applying a tourniquet to the affected limb.

The tourniquet is inflated to 50–100mm above systolic BP and a mixture of local anaesthetic, usually prilocaine and guanethidine, is injected into a cannula placed in the affected limb. After 20 minutes the tourniquet is deflated.

The technique has been used to treat pain associated with sympathetic hyperactivity and is also used for the treatment of type 1 CRPS (reflex sympathetic dystrophy).

Recent literature reviews suggest that there are no satisfactory trials demonstrating the effectiveness of this technique, but it appears widely used in clinical practice.

Increased sensitivity to stimulation excluding the special senses.

Increased sensitivity to painful stimuli.

A painful syndrome characterised by an increased reaction to a stimulus, especially a repeated stimulus, as well as a decreased pain threshold. Dermatomal spread may also occur.

The ways in which individuals think, feel and act in relation to their health status.


A pain assessment tool developed by Melzack and Torgerson to measure the quality of pain the patient experiences. Patients are presented with a list of 102 words grouped into 20 different categories. The categories are divided into three major classes:

  • Sensory qualities of pain.
  • Affective qualities including emotional aspects and fear associated with painful experiences.
  • Evaluative summary of the intensity of the overall pain experienced.

The questionnaire can be analysed and a pain rating index is obtained. The present pain intensity is also noted. A simpler version of the tool, the Short Form McGill questionnaire, was devised in 1987.

A regional pain syndrome accompanied by trigger points. It is distinguished from fibromyalgia in that in the latter there is generalised pain. Trigger points are characterised by localised tenderness, the presence of a taut band, referred pain on palpation over a trigger point site and a twitch response.

The exact aetiology is uncertain, but it is thought that local damage in muscle increases metabolic activity associated with decreased oxygen supply. Damage to the sarcoplasmic reticulum leads to abnormal contraction of muscle fibres. Diagnosis requires that all of the major criteria be met and at least one of the minor criteria.

Major criteria:

  • Localised spontaneous pain.
  • Pain in the expected referral area of the trigger point.
  • Taut palpable band in a muscle.
  • Exquisite tenderness in a particular point along the taut band.
  • Reduced range of movement.

Minor criteria:

  • Pressure on trigger point reproduces the patient`s pain.
  • Eliciting a local twitch response by ‘snapping palpation`.
  • Pain relieved by stretching the muscle or injecting the tender spot.

Pain arising from abnormalities within the central or peripheral nervous system, associated with injury, damage or dysfunction of the nervous system.

Examples of neuropathic pain syndromes include pain after brachial plexus avulsion, postherpetic neuralgia, complex regional pain syndromes and Pancoast syndrome.

Pain is normally experienced when A β and C fibres are activated by nociceptive stimuli, giving rise to normal or nociceptive pain. In contrast, in neuropathic pain, stimuli which are not normally considered to be noxious can produce pain, for example lightly touching or stroking of the affected area may be painful to some patients.

A diverse group of drugs with a broadly similar pharmacology. Opioids work by binding to μ κ and δ receptors in the CNS.

Opioids are commonly prescribed for moderate to severe pain, particularly for palliative care, cancer pain and chronic non-cancer pain. They can also be used in mild to moderate pain that cannot be controlled adequately by NSAIDs, such as postoperative or dental pain.

The impact of opioids on bowel function :
Opioids also bind to receptors in the enteric nervous system within the gastro-intestinal tract. Every type of opioid has an impact on gastro-intestinal function and can cause a variety of symptoms. All patients are at risk of developing the most prevalent and uncomfortable side-effect, constipation.

When opioids bind to the gastrointestinal receptors, particularly the m-receptor, the release of excitatory and inhibitory neurotransmitters is blocked. This interrupts the propulsive rhythmic contractions required for intestinal motility and reduces mucosal secretions. Opioid receptor activation within the bowel wall interferes with normal tone and contractility, delaying transit time of the faecal contents.

Constipation can add to patient discomfort and may serve as a barrier to effective pain management, limiting therapy or even prompting discontinuation.

Increased contractions of circular muscles cause non-propulsive kneading, churning and increased fluid absorption, which dries and hardens the stool. Drying of the stool is worsened by a decrease in longitudinal propulsive peristalsis, which occurs at the same time. In addition, anal sphincter tone is increased. This reduces reflexive relaxation in response to rectal distension, making defecation more difficult.

It is known that some tolerance develops to the effects of opioids on gastrointestinal motility, but constipation often persists unless effective measures are taken.

The International Association for the Study of Pain (IASP) defines pain as ‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage’.

IASP adds that pain is always a subjective sensation, always unpleasant and also an emotional experience.

A multidisciplinary method of helping those with chronic pain; usually, but not exclusively, back pain. This requires the input of physiotherapists, psychologists, occupational therapists, nurses and pain clinicians.

The purpose is to focus on the effects of pain on behaviour, mood, function and activity, rather than reducing the intensity of pain. Patients need to be carefully selected to ensure that they understand that such a programme is the start of them taking more responsibility for the management of their painful condition.

Although the pain is not cured, the programme will help to reduce fear avoidance behaviour in those with chronic pain.

In chronic pain syndromes, including cancer pain, the most common route of administration is either by mouth or transdermal delivery. However, where acute pain is very severe, such as in postoperative pain, it is often appropriate to deliver analgesic drugs intravenously.

The majority of opioids can be used in this fashion and IV morphine remains the drug of choice in many post-anaesthetic care units. Preparations such as oxycodone are now available, allowing a greater degree of choice in treating postoperative pain.

It is important to bear in mind that the analgesic effect is not instantaneous and in general it will take approximately 20 minutes for peak effect to be attained.

It is becoming increasingly common for non-medical staff such as nurses to administer IV opioids as part of a post-operative analgesic protocol.

This is a method of administering a variety of analgesics where the patient has control over how much of the drug they receive up to a predetermined limit, and how often they receive the drug.

This enables the patient to feel more in control of their pain management and reduces nursing time. It is most commonly used in acute postoperative pain and is sometimes used in cancer pain.

It is important that only the patient presses the demand button, not relatives or nurses. Patient-controlled analgesia should only be used on wards where established protocols exist and where staff have been trained in the safe management of such systems. Recordings of pain scores, sedation scores and respiratory rates should be made on a regular basis.

An unpleasant painful sensation referred to a surgically removed limb or portion thereof. This should be distinguished from phantom sensations and pain localised in the amputation stump (see stump pain).

The incidence of phantom pain in the literature can range from 5 to 80 per cent, depending on the particular study. Severe phantom pain is suggested to occur in up to 5 per cent of amputees. Pain is present in 50 to 75 per cent of patients in the first weeks following amputation.

Pain persisting beyond six months after amputation is notoriously difficult to treat. It is important not to attribute all pain in amputees to phantom pain and a careful history is necessary to elicit the exact cause. Other causes include stump pain, neuromata and ill-fitting prosthetic limbs.

One of the most common complications of zoster virus infection. Pain persists after the rash has healed. Some consider the starting point of PHN to be approximately one month after the onset, while others suggest that pain persisting three months after the initial eruption may be termed PHN.

People over the age of 60 are particularly at risk; 30 to 50 per cent of those in this age group will suffer with PHN to some degree.

The most common sites are in the mid-thoracic dermatomes and in the ophthalmic division of the trigeminal nerve.

Around 30 per cent of patients still suffer from PHN 12 months after the onset. In some cases pain persists for many years.

The pain is described as a severe burning sensation with superimposed stabbing or electric shock type sensations. The skin is often extremely sensitive and patients will avoid wearing tight fitting clothes.

Treatment consists of TCAs started as early as possible and topical substance P antagonists. There is some suggestion that the use of sympathetic blockade early on in the condition can reduce the intensity of PHN.

It is suggested that by using analgesic techniques before surgery it may be possible to reduce the intensity and duration of post-operative pain.

This is based on the hypothesis that if it is possible to prevent nociceptive impulses reaching the spinal cord then it may be possible to reduce hyperexcitability and other changes occurring in the dorsal horn.

There is convincing evidence in animal models that the hypothesis is valid. However, it has been extremely difficult to consistently reproduce these results when tested in human clinical studies.

A technique whereby an electrode is inserted either percutaneously or via a surgical laminotomy into the epidural space, enabling an electric current to be applied to the spinal cord via either an internal or external pulse generator.

Patients commonly undergo a period of trial stimulation in which they are allowed to experience the sensation on a temporary basis to see if they can achieve a 50–70 per cent reduction in their pain levels. Spinal cord stimulation is used to treat pain arising from a variety of conditions and the degree of success varies depending on the painful condition.

Successful pain relief is almost certain in pain due to intractable angina pectoris and ischaemic limb pain; and very likely in CRPS and amputation stump pain. Success with spinal cord stimulation is also possible in pain due to failed back surgery syndrome, and results compare well with those obtained by further revision surgery.

The incidence of stump pain varies according to published studies, but it has been found that one year after amputation approximately 13 per cent of patients still suffer from stump pain.

Stump pain is to be distinguished from phantom pain. Pain occurring in the residual stump occurs in up to 50 per cent of cases in the first weeks after amputation.

The quality of the pain can be described as soreness or a stabbing sensation; in addition a burning sensation in the stump can occur. It is important to carefully assess the patient as there can be a variety of causes including neuromata, progression of ischaemic pain in cases of peripheral vascular disease, poorly fitting prostheses or bony spurs.

Traditionally analgesics have been given by oral, buccal, subcutaneous, IV or IM routes. In a small number of cases it is appropriate to introduce analgesic agents into either the cerebrospinal fluid or the epidural space. The main disadvantage of these intermittent dosage regimens is that peaks and troughs occur in analgesic plasma levels.

Transdermal delivery of analgesic drugs provides minimal fluctuation in analgesic plasma levels. Advantages include prolonged analgesia which avoids a rapid peak and troughs of analgesic plasma levels.

Compliance is improved because it is generally considered more acceptable to replace a patch after three to seven days rather than take regular oral medication. The sites of delivery can be changed regularly.

The main requirements for a transdermal analgesic are low molecular weight, good lipid solubility and a high analgesic potency.

Fentanyl patches have been in use for several years and provide a variety of strengths releasing from 12 to 100 micrograms per hour. The patches are licensed for chronic intractable malignant and non-malignant pain.

There are also two buprenorphine patches. The most recent is a seven-day duration, low-dose buprenorphine patch, licensed for the treatment of non-malignant pain of moderate intensity when an opioid is necessary for obtaining adequate analgesia. This patch is available in three strengths (delivering 5, 10 and 20 micrograms of buprenorphine per hour).

The treatment will enable patients with moderate pain due to osteoarthritis, for example, to start on a low dose of buprenorphine and increase in slow increments to a level that allows optimum control of their pain.

A second buprenorphine patch is also available in three strengths, but at a higher dose, releasing 35, 52.5 and 70 micrograms per hour. It is a twice-weekly patch and is licensed for moderate to severe cancer pain and severe chronic non-malignant pain not responding to non-opioid analgesics.

Transdermal patches are not licensed for the treatment of acute pain.

A chronic painful condition characterised by severe pain, usually stabbing or like an electric shock in the distribution of the trigeminal nerve. Pain can last from seconds to minutes, is almost always unilateral, and can be triggered by brushing teeth, face washing or a cold wind. On physical examination there are no sensory defects. Between the episodes of pain there is no background discomfort.

Often the cause can be a tortuous blood vessel compressing the nerve root. Treatment consists of the use of anticonvulsants to reduce the frequency and severity of attacks, glycerol injection into the gasserian ganglion, radiofrequency ablation of the gasserian ganglion and surgical interventions, including microvascular decompression of the trigeminal nerve and, less commonly, tractotomy.

Stimulation of the sensory myelinated A β fibres to produce a pleasant, gentle tingling sensation. A pulse generator delivers current to the skin via electrodes, usually placed proximal to the painful area. The patient is able to control the amplitude or intensity of the impulse, the frequency and the pulse width.

TENS should not be used on the anterior part of the neck, in pregnancy or in the presence of a cardiac pacemaker.