1. PAIN – A general overview

2. Definition
According to the International association for the study of pain, pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage (IASP, 2015). It is a protective sensation as it prompts an individual to withdraw from damaging situations or stimuli. Pain is the reason why most people seek medical consultation in developed countries.

3. Prevalence of Pain
The global prevalence of pain is 20% and the incidence rate is 10% per annum (Goldberg and McGee, 2011).
In the UK, the prevalence is as high as 43.5% (Fayaz et. al., 2016).
And in Canada, one out of every five individuals suffers from pain (The Canadian Pain Society, 2014).
This implies that 1 in every 5 persons in the world suffers from pain

4. Classification and types of Pain
Classification of pain varies depending on the criterion used and classifications may overlap.
However, for clarity and simplicity, pain can be classified base on:
Duration
Cause and
Location

5. Classification by duration
Acute Pain: in most cases, acute pain begins suddenly and it is self-limited (usually stops as soon as the damaged tissue heals). It can last for as long as 6 months.
Chronic Pain: Chronic pain is usually associated with long-term illnesses, such as osteoarthritis and it persists even after tissue healing is complete. It can persist for years.

6. Classification by location
Somatic pain: Somatic pain originates from the skin and the deep tissues.
Visceral pain: Visceral pain comes from internal organs. It is not easily localised like somatic pain because most visceral organs have few or no pain receptors (nociceptors). Pain from these organs is felt in other parts of the body (e.g. Angina pectoris or chest pain). This is called referred pain.

7. Classification by cause
Nociceptive pain: This is a pain caused by damage to body tissues e.g. bone, soft tissues, or organs. These damages are picked up by nociceptors and relayed to the brain and spinal cord for interpretation and response.
Neuropathic pain: This is caused by nerve damage which can result from diabetes, HIV, stroke some chemotherapy drugs, trauma etc.

8. Classification of Pain Cont’d

9. Treatment and management of Pain
Treatment of pain depends largely on whether the pain is acute or chronic
The therapy of acute pain is aimed at treating the underlying cause by:
Resting the affected part
Application of heat or ice
Use of non-steroidal anti-inflammatory drugs (NSAIDs)
Physical therapy
Bioelectric therapy
Opioid (narcotic) medications (such as codeine or morphine)

10. Treatment and management of Pain Cont’d
The therapy of chronic pain rely on a multidisciplinary approach and involves more than one therapeutic modality. This may include:
pain medicines which may be pills, topical analgesics, cooling sprays or injections
physical therapy and complementary therapies and
surgery (used in rare cases)

11. References
Assessment of pain (2008). Br J Anaesth. 101(1):17–24. Debono DJ., Hoeksema LJ., Hobbs RD., (2013). "Caring for Patients with Chronic Pain: Pearls and Pitfalls". Journal of the American Osteopathic Association. 113(8): 620–627 Goldberg DS and McGee SJ., Pain as a global public health priority. BMC Public Health 2011(11): 770. Grichnik KP., Ferrante FM., The difference between acute and chronic pain. Mt Sinai J Med. 58(3): International Association for the Study of Pain (2015). Pain Definitions. Derived from The need of a taxonomy. Pain. 1979; 6(3):247–8. Lynch ME., Schopflocher D., Taenzer P and Sinclair C., Research Funding for pain in Canada. Pain Res Manage 14: Schopflocher D., Taenzer P., and Jovey R., The prevalence of chronic pain in Canada. Res Manage 16(6): Taxonomy and classification of pain. The Handbook of Chronic Pain. Nova Biomedical Books; ISBN The neurobiology of pain: Symposium of the Northern Neurobiology Group, held at Leeds on 18 April Manchester: Manchester University Press; ISBN Cutaneous nociceptors. p What should be the core outcomes in chronic pain clinical trials?. Arthritis Research & Therapy. 2004;6(4):151–4