Chronic pain management

Vasu, Thanthullu , Balasubramanian, Shyam, Kodivalasa, Mahesh , Ingle, Pradeep Mukund

• Publisher: tfm Publishing Ltd
• Year: 2021
• ISBN:
  9781910079928
• Topic: Medicina
• Subtopic: Anestesiología y gestión del dolor

Chronic pain is a silent epidemic — it is estimated to affect 20-30% of the population. A good understanding of the disease, diagnosis and management are imperative in providing patient-centred care. A broad range of practitioners will frequently encounter patients with chronic pain. This book covers important topics in chronic pain relevant to many clinicians including, but not limited to, anaesthetists, intensive care professionals, surgical and nursing staff, junior doctors, operating department practitioners, general practitioners and medical students. It makes essential reading for healthcare workers and is also an invaluable first reference for physiotherapists, healthcare managers, psychologists and researchers with a need for an overview of the key aspects of this topic. This book will not only be an invaluable resource for trainee anaesthetists but also for practising anaesthetists with an interest in teaching the basics of chronic pain; it is also a succinct aid for clinical practice. Medical students and junior doctors, who are about to embark on a career in anaesthesia or intensive care medicine, will also find the book to be a useful educational tool. Subjects discussed range from the comprehensive assessment of chronic pain to the multimodal management of chronic pain. It is written in a simple and consistent style that can be easily understood and applied to day-to-day clinical practice.This material will be an important tool for professional exams. It is an ideal companion for candidates who are preparing for their final exams that include the topic of chronic pain and will help to assess their preparation and guide appropriate revision. Questions on chronic pain appear in written and structured oral examinations. This book will be handy for candidates preparing for examinations conducted by the Royal College of Anaesthetists, UK (FRCA), The College of Anaesthesiologists of Ireland (FCAI), the European Society of Anaesthesiology (EDAIC), the European Society of Intensive Care Medicine (EDIC), the Australian and New Zealand College of Anaesthetists (FANZCA), the National Board of Examinations of India (Dip NB), and the American and Canadian board exams, as well as other competitive exams across the globe. Candidates appearing for advanced pain examinations will find this book useful to refresh their knowledge on pain medicine. The authors are consultants in pain medicine with clinical and teaching experience in university hospitals across the UK. They regularly conduct successful pain education courses which consistently attract good feedback. They conduct regular final FRCA and FFPMRCA exam courses attended by candidates from all over the country.

Chapter1

Pain — definition and classification

Shyam Balasubramanian

Pain is defined as “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.” The International Association for the Study of Pain (IASP) has recently revised this definition (2020).

Table 1.1. Differences between acute and chronic pain.

Pain can be acute or chronic (■ Table 1.1). Chronic pain is defined as pain that lasts or recurs for longer than 3 months.

Acute pain	Chronic pain
The normal, predicted physiological response to an adverse chemical, thermal or mechanical stimulus associated with surgery, trauma and acute illness.	A pain state which is persistent and in which the cause of the pain may not be apparent.
Time-limited.	May be associated with a long-term incurable or intractable medical condition or disease.
Responsive to therapy.	Difficult to treat.

Chronic pain can be classified in different ways. Mainly, it can be due to malignancy or chronic non-cancer pain. The term ‘functional pain’ is used when patients present with pain of no obvious organic origin. One simple classification for chronic non-cancer pain is shown in ■ Figure 1.1.

Recently, the IASP has developed a new classification system for chronic pain. Basically, this system divides chronic pain into two classes — chronic primary pain or chronic secondary pain.

Figure 1.1. A simple classification for chronic non-cancer pain.

Chronic primary pain

Chronic primary pain is defined as pain in one or more anatomical regions that:

• Persists or recurs for longer than 3 months.

• Is associated with significant emotional distress (e.g. anxiety, anger, frustration or depressed mood) and/or significant functional disability (interference in activities of daily life and participation in social roles).

• The symptoms are not better accounted for by another diagnosis.

The subclassification of chronic primary pain is as follows:

• Chronic widespread pain.

• Complex regional pain syndrome (CRPS).

• Chronic primary headache or orofacial pain.

• Chronic primary visceral pain.

• Chronic primary musculoskeletal pain.

Chronic secondary pain

Chronic secondary pain syndromes are linked to other diseases as the underlying cause, for which pain may initially be regarded as a symptom.

The subclassification of chronic secondary pain includes:

• Chronic cancer-related pain — pain caused by the cancer itself (by the primary tumour or by metastases) or by its treatment (surgery, chemotherapy and radiotherapy).

• Chronic post-surgical or post-traumatic pain — chronic pain that develops or increases in intensity after a surgical procedure or a tissue injury and persists beyond the healing process, i.e. at least 3 months after the surgery or tissue trauma.

• Chronic neuropathic pain — pain caused by a lesion or disease of the somatosensory nervous system.

• Chronic secondary headache or orofacial pain.

• Chronic secondary visceral pain — persistent or recurrent pain originating from internal organs of the head or neck region or of the thoracic, abdominal and pelvic cavities. It is often associated with emotional, cognitive and behavioural disability.

• Chronic secondary musculoskeletal pain — chronic pain in bones, joints and tendons arising from an underlying disease. It can be due to persistent inflammation, associated with structural changes or caused by altered biomechanical function due to diseases of the nervous system.

In clinical practice, often these subclassifications coexist. For example, CRPS can present with a predominant neuropathic pain quality. Musculoskeletal back pain can cause sciatic nerve root irritation resulting in neuropathic radicular pain (sciatica). A Pancoast tumour (malignancy in the apex of the lung) can cause cancer pain, neuropathic pain due to involvement of the intercostal nerves and brachial plexus, musculoskeletal pain due to invasion into the intercostal muscles and chest wall, chemotherapy-induced peripheral neuropathic pain, etc.

Key Points

• Pain is an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.

• Pain can be acute or chronic; chronic pain can be primary or secondary.

• Often, various subclassifications of pain can coexist.

References

1. IASP terminology. The International Association for the Study of Pain. https://www.iasp-pain.org/Education/Content.aspx?ItemNumber=1698. Accessed on 20th July 2020.

2. Comment for IASP. https://www.iasp-pain.org/PublicationsNews/NewsDetail.aspx?ItemNumber=9218. Accessed on 20th July 2020.

3. Treede RD, Rief W, Barke A, et al. Chronic pain as a symptom or a disease: the IASP classification of chronic pain for the international classification of diseases: (ICD-11). Pain 2019; 160(1): 19-27.

Chapter2

Assessing a patient with chronic pain

Pradeep Mukund Ingle

Challenges in pain assessment

The challenges in pain assessment are:

• There is no objective measure available currently.

• It is a sensory and emotional experience.

• The complex, multidimensional and subjective nature of pain makes assessment difficult.

• Pain presentation may be both physical and behavioural.

• The amount of pain does not always correlate with the amount of actual tissue damage.

• Tests such as a functional MRI or PET-brain activation may show the areas in the brain that ‘light up’ in response to pain but these are not practical to perform in each patient on a regular basis.

Why should we assess pain?

The management of pain is dependent upon its severity. The cause of pain can be ascertained through the process of pain assessment.

The three dimensions of pain (ABCs of pain)

• Affective-motivational — relates to...